Understand and track your newborn's weight changes during the first few days of life.
Newborn Weight Loss Calculator
Enter the baby's weight at birth in kilograms (kg).
Enter the baby's lowest weight recorded after birth, in kilograms (kg).
Enter the number of days old the baby was when their lowest weight was recorded.
Optional: Enter the baby's weight after refeeding or feeding support, in kilograms (kg).
Calculation Results
—
Percentage Weight Loss: —%
Weight Lost (kg): — kg
Average Daily Weight Loss Rate (during initial loss): — kg/day
Weight Gain After Refeeding: — kg
Formula Used:
1. Total Weight Lost (kg) = Birth Weight – Lowest Recorded Weight
2. Percentage Weight Loss (%) = (Total Weight Lost / Birth Weight) * 100
3. Average Daily Weight Loss Rate (kg/day) = Total Weight Lost / Days Old at Lowest Weight
4. Weight Gain After Refeeding (kg) = Weight After Refeeding – Lowest Recorded Weight (if refeeding weight is provided)
Weight Trend Visualization
Weight progression over the first few days.
Weight Data Summary
Metric
Value
Unit
Birth Weight
—
kg
Lowest Recorded Weight
—
kg
Days Old at Lowest Weight
—
Days
Total Weight Lost
—
kg
Percentage Weight Loss
—
%
Average Daily Loss Rate
—
kg/day
Weight After Refeeding
—
kg
Weight Gain After Refeeding
—
kg
What is Newborn Weight Loss Calculation?
Newborn weight loss calculation refers to the process of determining how much weight a baby loses in the first few days after birth and expressing this loss as a percentage or rate. It's a crucial aspect of monitoring a baby's health and transition to life outside the womb. Most newborns experience some degree of weight loss, typically due to shedding excess fluid, meconium (the first stool), and a natural reduction in intake before milk production is fully established. Understanding the newborn weight loss calculation formula helps parents and healthcare providers assess if the loss is within normal physiological ranges.
Who Should Use It?
This calculation is primarily used by parents, pediatricians, neonatologists, and nurses to monitor the well-being of a newborn infant during their initial postnatal period. It's particularly important for:
New parents seeking to understand normal physiological changes.
Healthcare professionals assessing hydration, feeding effectiveness, and overall infant health.
Babies born prematurely or with specific health conditions that might affect weight gain.
Anyone interested in the typical growth patterns of a newborn.
Common Misconceptions
Several misconceptions surround newborn weight loss. One common myth is that any weight loss is a sign of a serious problem. In reality, a small degree of weight loss is normal and expected. Another misconception is that babies should regain their birth weight immediately. While rapid regain is desirable, it usually takes about 7-14 days. Understanding the newborn weight loss calculation formula clarifies these expectations.
Newborn Weight Loss Calculation Formula and Mathematical Explanation
The core of understanding newborn weight loss lies in a straightforward set of calculations. The primary goal is to quantify how much weight a baby has lost relative to their birth weight and to track this loss over time.
Total Weight Lost (in kg): This is the absolute amount of weight the baby has shed.
Percentage Weight Loss (in %): This normalizes the weight lost against the baby's initial birth weight, making it easier to compare across different birth weights.
Average Daily Weight Loss Rate (in kg/day): This helps track the pace of weight loss, usually over the first 2-5 days.
Step-by-Step Derivation and Variable Explanations
Let's break down the components:
1. Total Weight Lost (kg)
This is calculated by subtracting the baby's lowest recorded weight from their birth weight.
Formula: Total Weight Lost (kg) = Birth Weight (kg) – Lowest Recorded Weight (kg)
2. Percentage Weight Loss (%)
To find the percentage, we divide the total weight lost by the birth weight and multiply by 100.
Formula: Percentage Weight Loss (%) = (Total Weight Lost (kg) / Birth Weight (kg)) * 100
Generally, a weight loss of up to 7-10% of birth weight is considered normal in the first few days for healthy, full-term infants.
3. Average Daily Weight Loss Rate (kg/day)
This metric indicates how quickly the baby is losing weight. It's calculated by dividing the total weight lost by the number of days old the baby was when their lowest weight was recorded.
Formula: Average Daily Weight Loss Rate (kg/day) = Total Weight Lost (kg) / Days Old at Lowest Weight (days)
4. Weight Gain After Refeeding (kg) (Optional)
If a weight is recorded after intervention (like improved latch or supplementation), this measures the recovery.
Formula: Weight Gain After Refeeding (kg) = Weight After Refeeding (kg) – Lowest Recorded Weight (kg)
Variables Table
Variable
Meaning
Unit
Typical Range
Birth Weight
Weight of the baby immediately after birth.
kg
2.5 – 4.5 kg (for full-term)
Lowest Recorded Weight
The minimum weight measured after birth, typically by day 3-5.
kg
Typically 3-7% less than birth weight
Days Old at Lowest Weight
Age of the baby when their lowest weight was measured.
Days
1 – 5 days
Total Weight Lost
Absolute difference between birth weight and lowest weight.
kg
Varies, but often 0.1 – 0.4 kg
Percentage Weight Loss
Weight lost as a proportion of birth weight.
%
<= 10% (normal)
Average Daily Weight Loss Rate
The average rate of weight loss per day.
kg/day
~0.03 – 0.08 kg/day
Weight After Refeeding
Weight measured after feeding support or improved feeding.
kg
Should be increasing
Weight Gain After Refeeding
Increase in weight after feeding interventions.
kg
Positive value indicating gain
Key variables used in newborn weight loss calculations.
Baby Anya is born weighing 3.60 kg. On day 3 of life, her weight is recorded as 3.35 kg. This is her lowest weight.
Inputs:
Birth Weight: 3.60 kg
Lowest Recorded Weight: 3.35 kg
Days Old at Lowest Weight: 3 days
Calculations:
Total Weight Lost = 3.60 kg – 3.35 kg = 0.25 kg
Percentage Weight Loss = (0.25 kg / 3.60 kg) * 100 = 6.94%
Average Daily Weight Loss Rate = 0.25 kg / 3 days = 0.083 kg/day
Interpretation: Anya has lost 6.94% of her birth weight by day 3, averaging about 0.083 kg per day. This is within the generally accepted normal range of up to 10% weight loss.
Example 2: Newborn Requiring Feeding Support
Baby Ben is born weighing 3.80 kg. By day 4, his weight drops to 3.45 kg. Concerned, the parents seek help, and after some feeding support (improved latch, perhaps some breastfeeding support), his weight is measured again on day 5 at 3.50 kg.
Inputs:
Birth Weight: 3.80 kg
Lowest Recorded Weight: 3.45 kg
Days Old at Lowest Weight: 4 days
Weight After Refeeding: 3.50 kg
Calculations:
Total Weight Lost = 3.80 kg – 3.45 kg = 0.35 kg
Percentage Weight Loss = (0.35 kg / 3.80 kg) * 100 = 9.21%
Average Daily Weight Loss Rate = 0.35 kg / 4 days = 0.0875 kg/day
Weight Gain After Refeeding = 3.50 kg – 3.45 kg = 0.05 kg
Interpretation: Ben lost 9.21% of his birth weight by day 4, which is close to the upper limit of normal. The feeding support helped him gain 0.05 kg by day 5, indicating a positive response. Continued monitoring of infant feeding tips and weight is recommended.
How to Use This Newborn Weight Loss Calculator
Our calculator simplifies the process of tracking your baby's initial weight changes. Follow these steps to get accurate results:
Step-by-Step Instructions
Enter Birth Weight: Input the exact weight of your baby as recorded immediately after birth, in kilograms (e.g., 3.5).
Enter Lowest Recorded Weight: Provide the lowest weight your baby has reached since birth, also in kilograms (e.g., 3.2).
Enter Days Old: Specify the baby's age in days when this lowest weight was measured (e.g., 3).
Enter Refeeding Weight (Optional): If your baby has received interventions or is showing signs of weight recovery and you have a recorded weight after this, enter it here.
Click 'Calculate': The calculator will instantly process the numbers.
How to Read Results
Primary Result (Percentage Weight Loss): This is the most critical number, displayed prominently. A loss below 10% is generally considered normal for healthy, full-term babies.
Weight Lost (kg): The total absolute weight lost.
Average Daily Weight Loss Rate: Shows the pace of loss. High rates might warrant closer attention.
Weight Gain After Refeeding: Indicates if feeding interventions are effective.
The accompanying table provides a detailed breakdown, and the chart visualizes the trend. Use these insights to have informed discussions with your healthcare provider, especially if you have concerns about baby care guide and feeding.
Decision-Making Guidance
While this calculator provides valuable data, it is not a substitute for professional medical advice. If your baby's weight loss exceeds 10%, they seem lethargic, have fewer wet diapers, or you have any concerns, consult your pediatrician or a lactation consultant immediately. They can assess the situation holistically, considering factors beyond just weight.
Key Factors That Affect Newborn Weight Loss
Several physiological and external factors influence how much weight a newborn loses and how quickly they regain it. Understanding these helps contextualize the newborn weight loss calculation formula results:
Gestational Age: Premature babies may lose a higher percentage of their birth weight and take longer to regain it compared to full-term infants due to immature digestive and metabolic systems.
Feeding Method and Adequacy: Breastfed babies may experience slightly higher initial weight loss than formula-fed babies because colostrum (early breast milk) is less voluminous than formula, and milk supply takes time to establish. Inadequate or inefficient feeding (poor latch, low milk transfer) is a primary driver of excessive weight loss.
Hydration Status: Newborns lose fluid through urine, stool, and insensible water loss (skin, respiration). Dehydration can exacerbate weight loss. Monitoring diaper output is crucial.
Meconium and Stool Output: The passage of meconium (dark, tarry first stool) and subsequent transitional stools contributes to weight loss. More frequent and larger stools mean more weight loss.
Maternal Health and Medications: Certain maternal conditions (like diabetes) can affect birth weight and fluid balance. Medications taken by the mother can also influence the baby's metabolism and fluid handling.
Birth Trauma or Complications: Difficult births can sometimes lead to fluid shifts or delayed feeding initiation, impacting weight loss patterns.
Environmental Factors: While less significant for typical weight loss, extreme temperatures or prolonged exposure could theoretically impact fluid balance, though this is rarely a primary concern in standard hospital/home environments.
Underlying Medical Conditions: Rare conditions affecting the baby's gastrointestinal tract, metabolism, or endocrine system can influence weight management.
Frequently Asked Questions (FAQ)
Q1: What is the normal percentage of newborn weight loss?
A: For healthy, full-term newborns, a weight loss of up to 7-10% of their birth weight in the first few days is considered normal and physiological.
Q2: When do newborns typically reach their lowest weight?
A: Most newborns reach their lowest weight between 24 to 72 hours (1-3 days) after birth.
Q3: How long does it take for a baby to regain birth weight?
A: Typically, newborns regain their birth weight by 7 to 14 days of age. This can vary depending on birth weight and feeding.
Q4: My baby lost more than 10% of their birth weight. Should I be worried?
A: Yes, significant weight loss over 10% warrants prompt evaluation by a healthcare professional to rule out issues like dehydration, insufficient feeding, or underlying medical problems. Consult your pediatrician immediately.
Q5: Does the type of feeding (breast vs. formula) affect the weight loss calculation?
A: While both breastfed and formula-fed babies lose weight initially, breastfed babies might lose slightly more percentage-wise due to the nature of colostrum and the time it takes for mature milk to come in. The newborn weight loss calculation formula itself remains the same, but interpretation might consider feeding method.
Q6: What if I can't accurately measure my baby's weight?
A: Home scales are often not precise enough for accurate infant weight tracking. It's best to rely on weights taken by healthcare professionals using calibrated scales. If you must use a home scale, ensure it's a dedicated baby scale and use the same scale for all measurements.
Q7: Is the daily weight loss rate more important than the percentage?
A: Both are important. The percentage gives a good overall picture relative to their starting weight, while the daily rate helps track the speed of loss and recovery. A rapid daily loss rate, even if the total percentage is still borderline, can be concerning and indicates a need for swift intervention.
Q8: Can I use this calculator for premature babies?
A: While the formula can be applied, the "normal" ranges for premature babies differ significantly. Premature infants often lose more weight and take longer to regain it. Always follow the specific guidance provided by the neonatology team for premature infants.
Related Tools and Internal Resources
Baby Growth Tracker Tool: Monitor your baby's weight and length over months and years to compare against standard growth charts.
Infant Feeding Guide: Learn about different feeding methods, signs of adequate intake, and common feeding challenges.
Newborn Care Essentials: A comprehensive guide covering everything from bathing and sleeping to diapering and recognizing feeding cues.
Pediatrician Visit Checklist: Prepare for your baby's well-child visits with a list of questions and topics to discuss.
Understanding Baby Milestones: Explore developmental milestones for babies from birth to one year, including physical, cognitive, and social development.
Signs of Dehydration in Babies: Recognize the critical signs that your baby may be dehydrated and when to seek immediate medical attention.
var ctx;
var weightChart;
function validateInput(value, id, min, max, fieldName) {
var errorElement = document.getElementById(id + "Error");
errorElement.textContent = "";
errorElement.classList.remove("visible");
if (value === null || value === "") {
errorElement.textContent = fieldName + " cannot be empty.";
errorElement.classList.add("visible");
return false;
}
var numValue = parseFloat(value);
if (isNaN(numValue)) {
errorElement.textContent = fieldName + " must be a valid number.";
errorElement.classList.add("visible");
return false;
}
if (min !== null && numValue max) {
errorElement.textContent = fieldName + " cannot be greater than " + max + ".";
errorElement.classList.add("visible");
return false;
}
return true;
}
function calculateNewbornWeightLoss() {
var birthWeightInput = document.getElementById("birthWeight");
var lowestWeightInput = document.getElementById("lowestWeight");
var daysOldInput = document.getElementById("daysOld");
var refeedWeightInput = document.getElementById("refeedWeight");
var birthWeight = parseFloat(birthWeightInput.value);
var lowestWeight = parseFloat(lowestWeightInput.value);
var daysOld = parseInt(daysOldInput.value);
var refeedWeight = refeedWeightInput.value !== "" ? parseFloat(refeedWeightInput.value) : null;
var errors = 0;
if (!validateInput(birthWeightInput.value, "birthWeight", 0.1, 10.0, "Birth Weight")) errors++;
if (!validateInput(lowestWeightInput.value, "lowestWeight", 0.1, 10.0, "Lowest Recorded Weight")) errors++;
if (!validateInput(daysOldInput.value, "daysOld", 1, 30, "Days Old")) errors++;
if (refeedWeight !== null && !validateInput(refeedWeightInput.value, "refeedWeight", 0.1, 10.0, "Weight After Refeeding")) errors++;
if (errors > 0) {
document.getElementById("primary-result").textContent = "–";
document.getElementById("percentageWeightLoss").textContent = "–";
document.getElementById("weightLostKg").textContent = "–";
document.getElementById("dailyLossRate").textContent = "–";
document.getElementById("refeedingImpact").style.display = 'none';
document.getElementById("chartSection").style.display = 'none';
document.getElementById("tableSection").style.display = 'none';
return;
}
if (lowestWeight > birthWeight) {
document.getElementById("lowestWeightError").textContent = "Lowest weight cannot be greater than birth weight.";
document.getElementById("lowestWeightError").classList.add("visible");
errors++;
}
if (refeedWeight !== null && refeedWeight 0) {
document.getElementById("primary-result").textContent = "–";
document.getElementById("percentageWeightLoss").textContent = "–";
document.getElementById("weightLostKg").textContent = "–";
document.getElementById("dailyLossRate").textContent = "–";
document.getElementById("refeedingImpact").style.display = 'none';
document.getElementById("chartSection").style.display = 'none';
document.getElementById("tableSection").style.display = 'none';
return;
}
var totalWeightLost = birthWeight – lowestWeight;
var percentageWeightLoss = (totalWeightLost / birthWeight) * 100;
var dailyLossRate = totalWeightLost / daysOld;
var primaryResultElement = document.getElementById("primary-result");
primaryResultElement.textContent = percentageWeightLoss.toFixed(2) + "%";
document.getElementById("percentageWeightLoss").textContent = percentageWeightLoss.toFixed(2);
document.getElementById("weightLostKg").textContent = totalWeightLost.toFixed(2);
document.getElementById("dailyLossRate").textContent = dailyLossRate.toFixed(3);
var refeedingImpactElement = document.getElementById("refeedingImpact");
var refeedingGainKgElement = document.getElementById("refeedingGainKg");
if (refeedWeight !== null) {
var refeedingGainKg = refeedWeight – lowestWeight;
refeedingImpactElement.style.display = 'block';
refeedingGainKgElement.textContent = refeedingGainKg.toFixed(2);
} else {
refeedingImpactElement.style.display = 'none';
}
// Update Table
document.getElementById("tableBirthWeight").textContent = birthWeight.toFixed(2);
document.getElementById("tableLowestWeight").textContent = lowestWeight.toFixed(2);
document.getElementById("tableDaysOld").textContent = daysOld;
document.getElementById("tableWeightLostKg").textContent = totalWeightLost.toFixed(2);
document.getElementById("tablePercentageWeightLoss").textContent = percentageWeightLoss.toFixed(2);
document.getElementById("tableDailyLossRate").textContent = dailyLossRate.toFixed(3);
var tableRefeedRow = document.getElementById("tableRefeedRow");
var tableRefeedGainRow = document.getElementById("tableRefeedGainRow");
var tableRefeedWeightElement = document.getElementById("tableRefeedWeight");
var tableRefeedingGainKgElement = document.getElementById("tableRefeedingGainKg");
if (refeedWeight !== null) {
tableRefeedRow.style.display = 'table-row';
tableRefeedGainRow.style.display = 'table-row';
tableRefeedWeightElement.textContent = refeedWeight.toFixed(2);
tableRefeedingGainKgElement.textContent = (refeedWeight – lowestWeight).toFixed(2);
} else {
tableRefeedRow.style.display = 'none';
tableRefeedGainRow.style.display = 'none';
}
document.getElementById("chartSection").style.display = 'block';
document.getElementById("tableSection").style.display = 'block';
updateChart(birthWeight, lowestWeight, daysOld, refeedWeight);
}
function updateChart(birthWeight, lowestWeight, daysOld, refeedWeight) {
var labels = ["Birth"];
var dataPoints = [birthWeight];
// Add points for daily loss up to lowest weight
for (var i = 1; i <= daysOld; i++) {
labels.push("Day " + i);
var currentWeight = birthWeight – (birthWeight – lowestWeight) * (i / daysOld);
dataPoints.push(currentWeight);
}
// Add point for refeeding weight if available
if (refeedWeight !== null) {
labels.push("Refeed Day " + (daysOld + 1)); // Assuming refeed happens day after lowest
dataPoints.push(refeedWeight);
}
if (!ctx) {
ctx = document.getElementById("weightChart").getContext("2d");
}
if (weightChart) {
weightChart.destroy();
}
weightChart = new Chart(ctx, {
type: 'line',
data: {
labels: labels,
datasets: [{
label: 'Baby's Weight (kg)',
data: dataPoints,
borderColor: 'var(–primary-color)',
backgroundColor: 'rgba(0, 74, 153, 0.1)',
fill: true,
tension: 0.1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: false
}
},
plugins: {
legend: {
display: true
},
title: {
display: true,
text: 'Newborn Weight Trend'
}
}
}
});
}
function resetCalculator() {
document.getElementById("birthWeight").value = "3.50";
document.getElementById("lowestWeight").value = "3.20";
document.getElementById("daysOld").value = "3";
document.getElementById("refeedWeight").value = "";
document.getElementById("birthWeightError").textContent = "";
document.getElementById("birthWeightError").classList.remove("visible");
document.getElementById("lowestWeightError").textContent = "";
document.getElementById("lowestWeightError").classList.remove("visible");
document.getElementById("daysOldError").textContent = "";
document.getElementById("daysOldError").classList.remove("visible");
document.getElementById("refeedWeightError").textContent = "";
document.getElementById("refeedWeightError").classList.remove("visible");
document.getElementById("primary-result").textContent = "–";
document.getElementById("percentageWeightLoss").textContent = "–";
document.getElementById("weightLostKg").textContent = "–";
document.getElementById("dailyLossRate").textContent = "–";
document.getElementById("refeedingImpact").style.display = 'none';
document.getElementById("chartSection").style.display = 'none';
document.getElementById("tableSection").style.display = 'none';
if (weightChart) {
weightChart.destroy();
ctx = null; // Reset canvas context reference
}
}
function copyResults() {
var primaryResult = document.getElementById("primary-result").innerText;
var percentageWeightLoss = document.getElementById("percentageWeightLoss").innerText;
var weightLostKg = document.getElementById("weightLostKg").innerText;
var dailyLossRate = document.getElementById("dailyLossRate").innerText;
var refeedingImpact = document.getElementById("refeedingImpact").style.display === 'block'
? "Weight Gain After Refeeding: " + document.getElementById("refeedingGainKg").innerText + " kg"
: "";
var birthWeight = document.getElementById("birthWeight").value;
var lowestWeight = document.getElementById("lowestWeight").value;
var daysOld = document.getElementById("daysOld").value;
var refeedWeightVal = document.getElementById("refeedWeight").value;
var assumptions = "Key Assumptions:\n";
assumptions += "- Birth Weight: " + birthWeight + " kg\n";
assumptions += "- Lowest Recorded Weight: " + lowestWeight + " kg\n";
assumptions += "- Days Old at Lowest Weight: " + daysOld + "\n";
if (refeedWeightVal !== "") {
assumptions += "- Weight After Refeeding: " + refeedWeightVal + " kg\n";
}
var resultsText = "— Newborn Weight Loss Calculation Results —\n\n";
resultsText += "Primary Result (Percentage Weight Loss): " + primaryResult + "\n";
resultsText += "Weight Lost: " + weightLostKg + " kg\n";
resultsText += "Average Daily Loss Rate: " + dailyLossRate + " kg/day\n";
if (refeedingImpact) {
resultsText += refeedingImpact + "\n";
}
resultsText += "\n" + assumptions;
// Use the modern Clipboard API if available
if (navigator.clipboard && navigator.clipboard.writeText) {
navigator.clipboard.writeText(resultsText).then(function() {
alert("Results copied to clipboard!");
}).catch(function(err) {
console.error("Could not copy text: ", err);
fallbackCopyTextToClipboard(resultsText);
});
} else {
fallbackCopyTextToClipboard(resultsText);
}
}
function fallbackCopyTextToClipboard(text) {
var textArea = document.createElement("textarea");
textArea.value = text;
textArea.style.position = "fixed"; // Avoid scrolling to bottom
textArea.style.left = "-9999px";
textArea.style.top = "-9999px";
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
alert('Results ' + msg + ' copied to clipboard!');
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
alert('Could not copy results. Please copy manually.');
}
document.body.removeChild(textArea);
}
// Initialize on load
document.addEventListener('DOMContentLoaded', function() {
resetCalculator(); // Set sensible defaults and clear results
document.getElementById("birthWeight").value = "3.50";
document.getElementById("lowestWeight").value = "3.20";
document.getElementById("daysOld").value = "3";
});
// Basic Chart.js inclusion – This assumes Chart.js library is loaded externally.
// For a self-contained HTML file as requested, you'd need to embed Chart.js
// or use a different charting method (like SVG or Canvas API directly).
// For this example, we will assume Chart.js is available.
// If not, you would need to:
// 1. Download Chart.js and include it via a local script tag, or
// 2. Re-implement charting using pure JS Canvas API or SVG.
// Given the constraints, a pure Canvas API approach is more feasible for self-containment.
// — Re-implementing Charting with Pure Canvas API —
var chartCanvas = document.getElementById("weightChart");
if(chartCanvas) {
chartCanvas.width = chartCanvas.clientWidth;
chartCanvas.height = chartCanvas.clientHeight;
ctx = chartCanvas.getContext("2d");
}
function drawChart(birthWeight, lowestWeight, daysOld, refeedWeight) {
if (!ctx) return;
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
var dataPoints = [];
var labels = ["Birth"];
var xScaleFactor = (ctx.canvas.width – 60) / Math.max(daysOld + (refeedWeight !== null ? 2 : 1), 5); // Ensure some minimum scale, +2 for refeed, +1 for birth
var yScaleFactor = (ctx.canvas.height – 60) / (birthWeight – Math.min(lowestWeight, refeedWeight || birthWeight) + 0.5); // Dynamic Y scale
var minY = birthWeight – (birthWeight – lowestWeight) * 1.1; // Add some buffer below lowest point
var maxY = birthWeight + 0.2; // Add some buffer above birth weight
yScaleFactor = (ctx.canvas.height – 60) / (maxY – minY);
var points = [];
// Birth point
points.push({ x: 30, y: ctx.canvas.height – 30 – (birthWeight – minY) * yScaleFactor });
labels.push("Birth");
// Daily loss points
var weightStep = (birthWeight – lowestWeight) / daysOld;
for (var i = 1; i <= daysOld; i++) {
var currentWeight = birthWeight – weightStep * i;
points.push({ x: 30 + i * xScaleFactor, y: ctx.canvas.height – 30 – (currentWeight – minY) * yScaleFactor });
labels.push("Day " + i);
}
// Refeeding point
if (refeedWeight !== null) {
// Assume refeeding point is roughly 1 day after lowest weight measurement day
points.push({ x: 30 + (daysOld + 1) * xScaleFactor, y: ctx.canvas.height – 30 – (refeedWeight – minY) * yScaleFactor });
labels.push("Day " + (daysOld + 1));
}
// Draw axes
ctx.beginPath();
ctx.moveTo(30, ctx.canvas.height – 30); // X-axis start
ctx.lineTo(ctx.canvas.width – 30, ctx.canvas.height – 30); // X-axis end
ctx.lineTo(ctx.canvas.width – 30, 30); // Y-axis end
ctx.lineTo(ctx.canvas.width – 30, ctx.canvas.height – 30); // Y-axis resume
ctx.moveTo(30, 30); // Y-axis start
ctx.lineTo(30, ctx.canvas.height – 30); // Y-axis path
ctx.strokeStyle = '#ccc';
ctx.lineWidth = 1;
ctx.stroke();
// Draw labels on X axis
ctx.fillStyle = '#333';
ctx.textAlign = 'center';
ctx.font = '12px Segoe UI';
for (var i = 0; i 0 && i < labels.length – 1) { // Avoid drawing labels too close or overlapping ends
ctx.fillText(labels[i], labelX, ctx.canvas.height – 15);
} else if (i === 0) { // Birth label
ctx.fillText(labels[i], labelX, ctx.canvas.height – 15);
} else if (i === labels.length – 1) { // Last label
ctx.fillText(labels[i], labelX, ctx.canvas.height – 15);
}
}
// Draw labels on Y axis (simplified)
ctx.textAlign = 'right';
ctx.textBaseline = 'middle';
var tickInterval = Math.max(1, Math.round((maxY – minY) / 5));
for (var val = minY; val 30 && tickY < ctx.canvas.height – 30) {
ctx.fillText(val.toFixed(1), 25, tickY);
ctx.beginPath();
ctx.moveTo(28, tickY);
ctx.lineTo(30, tickY);
ctx.stroke();
}
}
// Draw the line graph
ctx.beginPath();
ctx.moveTo(points[0].x, points[0].y);
for (var i = 1; i < points.length; i++) {
ctx.lineTo(points[i].x, points[i].y);
}
ctx.strokeStyle = 'var(–primary-color)';
ctx.lineWidth = 2;
ctx.stroke();
// Draw points
ctx.fillStyle = 'var(–primary-color)';
for (var i = 0; i < points.length; i++) {
ctx.beginPath();
ctx.arc(points[i].x, points[i].y, 4, 0, 2 * Math.PI);
ctx.fill();
}
}
function updateChart(birthWeight, lowestWeight, daysOld, refeedWeight) {
// Call the pure Canvas API drawing function
drawChart(birthWeight, lowestWeight, daysOld, refeedWeight);
}
// Override original updateChart to use the new drawChart
// Ensure the original calculateNewbornWeightLoss calls updateChart
// Make sure the DOMContentLoaded listener also calls resetCalculator which then sets initial values.