Calorie Calculator for Weight

Calorie Calculator for Weight | Scientific Weight Loss & Gain Planner :root { –primary: #004a99; –secondary: #003366; –success: #28a745; –bg-color: #f8f9fa; –text-color: #333; –border-color: #ddd; –shadow: 0 4px 6px rgba(0,0,0,0.1); } * { box-sizing: border-box; margin: 0; padding: 0; } body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; line-height: 1.6; color: var(–text-color); background-color: var(–bg-color); padding: 20px; } .container { max-width: 960px; margin: 0 auto; background: #fff; padding: 40px; border-radius: 8px; box-shadow: var(–shadow); } h1 { color: var(–primary); text-align: center; margin-bottom: 30px; font-size: 2.5rem; border-bottom: 2px solid var(–border-color); padding-bottom: 15px; } h2 { color: var(–secondary); margin-top: 40px; margin-bottom: 20px; font-size: 1.8rem; border-left: 5px solid var(–primary); padding-left: 15px; } h3 { color: var(–text-color); margin-top: 30px; margin-bottom: 15px; font-size: 1.4rem; } p { margin-bottom: 20px; } /* Calculator Styles */ .loan-calc-container { background-color: #fff; padding: 30px; border: 1px solid var(–border-color); border-radius: 8px; margin-bottom: 50px; } .input-group { margin-bottom: 20px; } .input-group label { display: block; font-weight: 600; margin-bottom: 8px; color: var(–secondary); } .input-group input, .input-group select { width: 100%; padding: 12px; border: 1px solid var(–border-color); border-radius: 4px; font-size: 16px; transition: border-color 0.3s; } .input-group input:focus, .input-group select:focus { border-color: var(–primary); outline: none; box-shadow: 0 0 0 3px rgba(0, 74, 153, 0.1); } .helper-text { font-size: 0.85rem; color: #666; margin-top: 5px; } .error-msg { color: #dc3545; font-size: 0.85rem; margin-top: 5px; display: none; } .radio-group { display: flex; gap: 20px; margin-bottom: 10px; } .radio-group label { display: flex; align-items: center; font-weight: normal; cursor: pointer; } .radio-group input { width: auto; margin-right: 8px; } .btn-group { display: flex; gap: 15px; margin-top: 30px; } button { padding: 12px 24px; border: none; border-radius: 4px; cursor: pointer; font-size: 16px; font-weight: 600; transition: background 0.3s; } .btn-reset { background-color: #6c757d; color: white; } .btn-copy { background-color: var(–primary); color: white; } .btn-reset:hover { background-color: #5a6268; } .btn-copy:hover { background-color: #003366; } /* Results Styles */ .results-section { margin-top: 40px; padding-top: 30px; border-top: 2px dashed var(–border-color); } .primary-result { background-color: #e8f0fe; padding: 25px; border-radius: 8px; text-align: center; margin-bottom: 30px; border: 1px solid #b3d7ff; } .primary-result h3 { margin-top: 0; color: var(–primary); font-size: 1.2rem; text-transform: uppercase; letter-spacing: 1px; } .big-number { font-size: 3.5rem; font-weight: 800; color: var(–primary); line-height: 1.2; } .big-number span { font-size: 1.5rem; color: #666; font-weight: 400; } .result-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 20px; margin-bottom: 30px; } .result-card { background: #fff; padding: 15px; border: 1px solid var(–border-color); border-radius: 6px; text-align: center; } .result-card strong { display: block; font-size: 1.5rem; color: var(–success); margin-top: 5px; } .formula-box { background: #f1f3f5; padding: 15px; border-radius: 6px; font-family: monospace; margin-bottom: 30px; font-size: 0.9rem; } /* Table & Chart */ .data-table { width: 100%; border-collapse: collapse; margin-bottom: 40px; } .data-table th, .data-table td { padding: 12px; text-align: left; border-bottom: 1px solid var(–border-color); } .data-table th { background-color: var(–primary); color: white; } .data-table tr:nth-child(even) { background-color: #f8f9fa; } .chart-container { width: 100%; height: 300px; border: 1px solid var(–border-color); border-radius: 8px; padding: 10px; margin-bottom: 10px; background: white; position: relative; } canvas { width: 100%; height: 100%; } .chart-legend { text-align: center; font-size: 0.9rem; color: #666; margin-bottom: 30px; } /* Article specific */ .article-content ul, .article-content ol { margin-left: 20px; margin-bottom: 20px; } .article-content li { margin-bottom: 8px; } .faq-item { margin-bottom: 20px; border-bottom: 1px solid var(–border-color); padding-bottom: 20px; } .faq-question { font-weight: 700; color: var(–primary); margin-bottom: 10px; display: block; } .internal-links { background-color: #f8f9fa; padding: 20px; border-radius: 8px; border-left: 4px solid var(–primary); } .internal-links ul { list-style: none; margin: 0; } .internal-links li { margin-bottom: 10px; } .internal-links a { color: var(–primary); text-decoration: none; font-weight: 600; } .internal-links a:hover { text-decoration: underline; } @media (max-width: 600px) { .container { padding: 20px; } .big-number { font-size: 2.5rem; } .btn-group { flex-direction: column; } }

Calorie Calculator for Weight

Accurately determine your daily energy needs. This professional calorie calculator for weight helps you find your TDEE and BMR to create a sustainable plan for weight loss, maintenance, or muscle gain.

Age in years
Please enter a valid age (15-100).
Feet
Inches
Please enter valid height values.
Current weight in pounds
Please enter a valid weight (50-600 lbs).
Height in centimeters
Please enter a valid height (100-250 cm).
Current weight in kilograms
Please enter a valid weight (30-300 kg).
Sedentary (Office job, little exercise) Lightly Active (1-3 days/week) Moderately Active (3-5 days/week) Very Active (6-7 days/week) Extra Active (Physical job + training)
Be honest for best results
Extreme Weight Loss (-2 lbs/week) Weight Loss (-1 lb/week) Maintain Weight Mild Weight Gain (+0.5 lb/week) Weight Gain (+1 lb/week)
Recommended: 1 lb/week for sustainable results

Your Daily Target

2,250 kcal/day

To lose 1lb per week

Maintenance Calories (TDEE) 2,750 Calories to stay same weight
Basal Metabolic Rate (BMR) 1,850 Calories burned at rest
Weekly Calorie Deficit 3,500 Total deficit/surplus per week

Calculation Formula Used:

Mifflin-St Jeor Equation: (10 × weight) + (6.25 × height) – (5 × age) + 5

Projected Weight Change (8 Weeks)

Solid Line: Projected Weight | Dashed Line: Maintenance Baseline

Macronutrient Breakdown (Moderate Carb)

Nutrient Percentage Calories Grams
*Based on a 30% Protein, 35% Fat, 35% Carb split suitable for general weight management.

What is a Calorie Calculator for Weight?

A calorie calculator for weight is a specialized financial-planning tool for your body's energy budget. Just as you manage finances by tracking income and expenses, effective weight management requires understanding your caloric "income" (food) versus your "expenses" (activity). This tool calculates your Total Daily Energy Expenditure (TDEE) and adjusts it based on your specific weight goals.

Whether you are looking to shed fat, build muscle, or maintain your current physique, knowing your numbers is the first step. This calculator uses the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating caloric needs in clinical settings.

Who should use this tool? Anyone starting a fitness journey, athletes planning a bulk/cut cycle, or individuals advised by medical professionals to manage their weight for health reasons.

Calorie Calculator for Weight: Formula and Math

The core logic behind this calculator relies on two steps: estimating your Basal Metabolic Rate (BMR) and then multiplying it by an activity factor to find your TDEE.

1. The Mifflin-St Jeor Equation

This formula calculates BMR, which is the energy your body needs just to keep organs functioning at rest.

  • Men: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
  • Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

2. Total Daily Energy Expenditure (TDEE)

Once BMR is known, we apply the Activity Factor:

Variable Meaning Multiplier
Sedentary Office job, little to no exercise 1.2
Lightly Active Light exercise 1-3 days/week 1.375
Moderately Active Moderate exercise 3-5 days/week 1.55
Very Active Heavy exercise 6-7 days/week 1.725

Practical Examples

Example 1: Weight Loss for a Sedentary Office Worker

Profile: John, 40 years old, 5'10" (178cm), 200 lbs (90.7kg).
Goal: Lose 1 lb per week.
Calculation:

  1. BMR: (10 × 90.7) + (6.25 × 178) – (5 × 40) + 5 = ~1,825 calories.
  2. TDEE (Sedentary 1.2): 1,825 × 1.2 = 2,190 calories.
  3. Deficit: To lose 1 lb of fat (approx 3,500 calories), he needs a daily deficit of 500.
  4. Target: 2,190 – 500 = 1,690 calories/day.

Example 2: Muscle Gain for an Active Athlete

Profile: Sarah, 28 years old, 5'6″ (167cm), 140 lbs (63.5kg).
Goal: Gain 0.5 lb per week.
Calculation:

  1. BMR: (10 × 63.5) + (6.25 × 167) – (5 × 28) – 161 = ~1,378 calories.
  2. TDEE (Very Active 1.725): 1,378 × 1.725 = 2,377 calories.
  3. Surplus: To gain 0.5 lb, she needs a daily surplus of 250 calories.
  4. Target: 2,377 + 250 = 2,627 calories/day.

How to Use This Calorie Calculator for Weight

  1. Select Unit System: Choose between Imperial (lbs/ft) or Metric (kg/cm).
  2. Enter Biometrics: Input your accurate gender, age, height, and current weight.
  3. Choose Activity Level: Be honest. Overestimating activity is the #1 reason calorie calculators fail for users. If unsure, choose the lower option.
  4. Select Goal: Choose your desired rate of weight loss or gain. A rate of 1 lb (0.5 kg) per week is widely considered sustainable.
  5. Review Results: The calculator instantly provides your daily target, macro breakdown, and a chart projecting your weight over the next 8 weeks.

Key Factors That Affect Results

While the calorie calculator for weight provides a solid baseline, several factors influence real-world results:

  1. Metabolic Adaptation: As you lose weight, your body requires less energy to move. You must recalculate your needs every 10-15 lbs lost.
  2. Muscle Mass vs. Fat: Muscle burns more calories at rest than fat. Two people of the same weight but different body compositions will have different BMRs.
  3. Non-Exercise Activity Thermogenesis (NEAT): Fidgeting, standing, and walking around the office can account for up to 15% of energy expenditure, often varying greatly between individuals.
  4. Thermic Effect of Food (TEF): Protein requires more energy to digest than fats or carbs. A high-protein diet effectively increases your calorie expenditure.
  5. Hormonal Fluctuations: Stress (cortisol), sleep deprivation, and menstrual cycles can cause water retention, masking fat loss on the scale.
  6. Accuracy of Tracking: The calculator gives you a number, but its success depends on your ability to track food intake accurately. Studies show people underestimate intake by 30% on average.

Frequently Asked Questions (FAQ)

How accurate is this calorie calculator for weight?

The Mifflin-St Jeor formula is accurate to within 10% for most individuals. However, individual metabolism varies. We recommend using the result as a starting point and adjusting after 2-3 weeks based on your actual progress.

Should I eat back my exercise calories?

Generally, no. The activity multiplier already accounts for your exercise. Adding exercise calories on top often leads to "double dipping" and stalling weight loss.

What is a safe calorie minimum?

Health organizations generally recommend women do not eat below 1,200 calories and men not below 1,500 calories per day without medical supervision to ensure adequate nutrient intake.

Why is my weight not changing despite a deficit?

Water retention from sodium, stress, or new exercise routines can mask fat loss. Also, verify you are weighing food portions rather than estimating.

Does nutrient timing matter?

For total weight loss, total daily calories matter more than timing. However, eating protein spaced throughout the day can help preserve muscle mass.

Can I use this for Ketogenic or Vegan diets?

Yes. Calories are the fundamental unit of energy regardless of the source. Use the macro table provided to adjust your fats/carbs based on your dietary preference.

How often should I recalculate?

Recalculate every time you lose or gain 5-10 lbs, as your caloric needs change with your body mass.

What if I hit a plateau?

Plateaus are normal. If weight doesn't move for 2 weeks, try reducing daily intake by 100-200 calories or increasing daily steps by 2,000.

© 2023 Financial Wellness & Health Tools. All rights reserved.

Disclaimer: This calorie calculator for weight is for informational purposes only. Consult a physician before starting any diet or exercise program.

// Global State var state = { units: 'imperial', gender: 'male', age: 30, heightFt: 5, heightIn: 9, heightCm: 175, weightLbs: 180, weightKg: 80, activity: 1.375, goal: -500 }; // Initialization (function init() { calculateCalories(); // Setup chart canvas resolution var canvas = document.getElementById('weightChart'); var rect = canvas.parentNode.getBoundingClientRect(); canvas.width = rect.width; canvas.height = 300; })(); // Helper: Toggle Units function toggleUnits() { var radios = document.getElementsByName('units'); for (var i = 0; i < radios.length; i++) { if (radios[i].checked) { state.units = radios[i].value; break; } } var imperialDiv = document.getElementById('imperial-inputs'); var metricDiv = document.getElementById('metric-inputs'); if (state.units === 'imperial') { imperialDiv.style.display = 'block'; metricDiv.style.display = 'none'; } else { imperialDiv.style.display = 'none'; metricDiv.style.display = 'block'; } calculateCalories(); } // Validation Logic function validateAndCalculate(input) { var id = input.id; var val = parseFloat(input.value); var errId = ""; if (id === 'age') errId = 'err-age'; if (id === 'weightLbs') errId = 'err-weight-imp'; if (id === 'weightKg') errId = 'err-weight-met'; if (id === 'heightCm') errId = 'err-height-met'; if (id === 'heightFt' || id === 'heightIn') errId = 'err-height-imp'; var isValid = true; var min = parseFloat(input.min); var max = parseFloat(input.max); if (isNaN(val) || val max) { isValid = false; document.getElementById(errId).style.display = 'block'; input.style.borderColor = '#dc3545'; } else { document.getElementById(errId).style.display = 'none'; input.style.borderColor = '#ddd'; } // Special case for Height FT/IN composite validation if (id === 'heightFt' || id === 'heightIn') { var ft = parseFloat(document.getElementById('heightFt').value); var inc = parseFloat(document.getElementById('heightIn').value); if (ft >= 3 && ft = 0 && inc <= 11) { document.getElementById('err-height-imp').style.display = 'none'; } } if (isValid) { calculateCalories(); } } // Core Calculation Logic function calculateCalories() { // Update State from DOM updateStateFromDOM(); // 1. Normalize Inputs to Metric var weightKg = state.weightKg; var heightCm = state.heightCm; if (state.units === 'imperial') { weightKg = state.weightLbs * 0.453592; var totalInches = (state.heightFt * 12) + state.heightIn; heightCm = totalInches * 2.54; } // 2. Calculate BMR (Mifflin-St Jeor) // Men: (10 × weight) + (6.25 × height) – (5 × age) + 5 // Women: (10 × weight) + (6.25 × height) – (5 × age) – 161 var bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * state.age); if (state.gender === 'male') { bmr += 5; } else { bmr -= 161; } // 3. Calculate TDEE var tdee = bmr * state.activity; // 4. Calculate Target var targetCalories = tdee + state.goal; // Safety check: Don't recommend dangerous lows if (targetCalories < 1200 && state.gender === 'female') targetCalories = 1200; if (targetCalories < 1500 && state.gender === 'male') targetCalories = 1500; // 5. Update UI displayResults(bmr, tdee, targetCalories); updateChart(weightKg, state.goal); updateMacroTable(targetCalories); } function updateStateFromDOM() { // Gender var genderRadios = document.getElementsByName('gender'); for (var i = 0; i < genderRadios.length; i++) { if (genderRadios[i].checked) state.gender = genderRadios[i].value; } // Numeric inputs state.age = parseFloat(document.getElementById('age').value) || 30; state.weightLbs = parseFloat(document.getElementById('weightLbs').value) || 180; state.weightKg = parseFloat(document.getElementById('weightKg').value) || 80; state.heightCm = parseFloat(document.getElementById('heightCm').value) || 175; state.heightFt = parseFloat(document.getElementById('heightFt').value) || 5; state.heightIn = parseFloat(document.getElementById('heightIn').value) || 9; // Selects state.activity = parseFloat(document.getElementById('activity').value); state.goal = parseFloat(document.getElementById('goal').value); } function displayResults(bmr, tdee, target) { document.getElementById('result-bmr').innerText = Math.round(bmr).toLocaleString(); document.getElementById('result-tdee').innerText = Math.round(tdee).toLocaleString(); document.getElementById('result-calories').innerHTML = Math.round(target).toLocaleString() + " kcal/day"; // Weekly Deficit/Surplus var weeklyDiff = state.goal * 7; var diffText = Math.abs(weeklyDiff).toLocaleString(); if (weeklyDiff 0) diffText = "+" + diffText + " (Surplus)"; else diffText = "0 (Maintenance)"; document.getElementById('result-deficit').innerText = diffText; // Goal Text update var goalLabel = document.getElementById('goal').options[document.getElementById('goal').selectedIndex].text; document.getElementById('goal-text').innerText = "Strategy: " + goalLabel; } function updateMacroTable(calories) { // Split: 30% Protein, 35% Fat, 35% Carb // Protein = 4 cal/g, Carb = 4 cal/g, Fat = 9 cal/g var pCal = calories * 0.30; var fCal = calories * 0.35; var cCal = calories * 0.35; var pGram = Math.round(pCal / 4); var fGram = Math.round(fCal / 9); var cGram = Math.round(cCal / 4); var tbody = document.getElementById('macro-table-body'); tbody.innerHTML = "Protein30%" + Math.round(pCal) + "" + pGram + "g" + "Fats35%" + Math.round(fCal) + "" + fGram + "g" + "Carbs35%" + Math.round(cCal) + "" + cGram + "g"; } // Chart Drawing Logic (Native Canvas, No Libraries) function updateChart(currentWeightKg, dailyDeficit) { var canvas = document.getElementById('weightChart'); var ctx = canvas.getContext('2d'); var width = canvas.width; var height = canvas.height; // Clear canvas ctx.clearRect(0, 0, width, height); // Parameters var weeks = 8; var kgPerCal = 7700; // approx calories per kg of fat var weeklyWeightChange = (dailyDeficit * 7) / kgPerCal; // Generate Data Points var data = []; var baseline = []; for (var i = 0; i <= weeks; i++) { data.push(currentWeightKg + (weeklyWeightChange * i)); baseline.push(currentWeightKg); } // Determine Scale var minW = Math.min.apply(null, data) – 2; var maxW = Math.max.apply(null, data) + 2; var range = maxW – minW; // Helper to map values to coordinates function getX(weekIndex) { return 40 + (weekIndex / weeks) * (width – 60); } function getY(weightVal) { return height – 30 – ((weightVal – minW) / range) * (height – 60); } // Draw Axes ctx.beginPath(); ctx.strokeStyle = '#ccc'; ctx.lineWidth = 1; // Y Axis ctx.moveTo(40, 10); ctx.lineTo(40, height – 30); // X Axis ctx.moveTo(40, height – 30); ctx.lineTo(width – 10, height – 30); ctx.stroke(); // Draw Baseline (Dashed) ctx.beginPath(); ctx.strokeStyle = '#999'; ctx.setLineDash([5, 5]); for (var i = 0; i <= weeks; i++) { var x = getX(i); var y = getY(baseline[i]); if (i === 0) ctx.moveTo(x, y); else ctx.lineTo(x, y); } ctx.stroke(); // Draw Projection (Solid) ctx.beginPath(); ctx.strokeStyle = '#28a745'; ctx.lineWidth = 3; ctx.setLineDash([]); for (var i = 0; i <= weeks; i++) { var x = getX(i); var y = getY(data[i]); if (i === 0) ctx.moveTo(x, y); else ctx.lineTo(x, y); } ctx.stroke(); // Draw Points & Labels ctx.fillStyle = '#004a99'; ctx.font = '12px Arial'; ctx.textAlign = 'center'; // X-Axis Labels (Weeks) for (var i = 0; i <= weeks; i += 2) { ctx.fillText("Wk " + i, getX(i), height – 10); } // Y-Axis Labels (Weight) ctx.textAlign = 'right'; ctx.textBaseline = 'middle'; var step = range / 5; for (var i = 0; i <= 5; i++) { var wVal = minW + (step * i); ctx.fillText(wVal.toFixed(1), 35, getY(wVal)); } } function resetCalculator() { document.getElementById('age').value = 30; document.getElementById('weightLbs').value = 180; document.getElementById('weightKg').value = 80; document.getElementById('heightFt').value = 5; document.getElementById('heightIn').value = 9; document.getElementById('heightCm').value = 175; document.getElementById('activity').value = "1.375"; document.getElementById('goal').value = "-500"; var units = document.getElementsByName('units'); units[0].checked = true; // Imperial toggleUnits(); var genders = document.getElementsByName('gender'); genders[0].checked = true; // Male calculateCalories(); } function copyResults() { var txt = "My Calorie Plan:\n"; txt += "Daily Target: " + document.getElementById('result-calories').innerText.replace(' kcal/day', '') + " kcal\n"; txt += "Maintenance (TDEE): " + document.getElementById('result-tdee').innerText + " kcal\n"; txt += "BMR: " + document.getElementById('result-bmr').innerText + " kcal\n"; txt += "Weekly Deficit: " + document.getElementById('result-deficit').innerText + "\n"; txt += "Strategy: " + document.getElementById('goal-text').innerText; var textArea = document.createElement("textarea"); textArea.value = txt; document.body.appendChild(textArea); textArea.select(); document.execCommand("Copy"); textArea.remove(); var btn = document.querySelector('.btn-copy'); var originalText = btn.innerText; btn.innerText = "Copied!"; setTimeout(function(){ btn.innerText = originalText; }, 2000); } // Resize listener for chart window.addEventListener('resize', function() { var canvas = document.getElementById('weightChart'); var rect = canvas.parentNode.getBoundingClientRect(); canvas.width = rect.width; calculateCalories(); });

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