Use this online calorie calculator to lose weight by computing your BMR, TDEE, and the safe calorie deficit you need for steady fat loss.
Personalized Calorie Deficit Calculator
Needed for BMR; valid range 10-100.
Enter a valid age between 10 and 100.
Male
Female
Used in the Mifflin-St Jeor BMR equation.
Select a gender.
Typical adult range 120-220 cm.
Enter height between 120 and 220 cm.
Used to calculate BMR and weekly change.
Enter weight between 35 and 250 kg.
Sedentary (little exercise)
Lightly active (1-3 days/week)
Moderately active (3-5 days/week)
Very active (6-7 days/week)
Athlete (twice daily)
Determines Total Daily Energy Expenditure (TDEE).
Select an activity level.
Safe range 0.1-1.5 kg/week; higher deficits may be unsustainable.
Enter a target loss between 0.1 and 1.5 kg/week.
Daily target: 0 kcal
Main result shows daily calorie intake to meet the chosen weight-loss speed.
BMR: 0 kcal/day
TDEE: 0 kcal/day
Daily deficit: 0 kcal
Time to lose 5 kg: 0 weeks
Formula: Mifflin-St Jeor for BMR, multiplied by activity factor for TDEE, then subtract daily deficit derived from weekly loss × 7700 ÷ 7.
TDEECalorie Target
Chart shows your maintenance (TDEE) versus target calories over upcoming weeks.
Projected weekly weight change based on your chosen deficit.
Week
Projected Weight (kg)
Weekly Loss (kg)
Daily Target (kcal)
What is online calorie calculator to lose weight?
The online calorie calculator to lose weight is a focused tool that estimates how many calories you should eat to lose fat at a chosen pace while maintaining energy and muscle. It uses your age, gender, height, weight, activity, and desired weekly loss to set a personalized target. People aiming for structured fat loss, athletes planning a cut, and anyone monitoring nutrition can benefit from the online calorie calculator to lose weight.
Common misconceptions about the online calorie calculator to lose weight include believing it sets rigid rules, ignores metabolism changes, or guarantees identical results for everyone. In reality, the online calorie calculator to lose weight offers a science-based starting point that must be adjusted with real-world feedback.
online calorie calculator to lose weight Formula and Mathematical Explanation
The online calorie calculator to lose weight uses the Mifflin-St Jeor equation for Basal Metabolic Rate (BMR):
For males: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 For females: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
TDEE = BMR × activity factor. The online calorie calculator to lose weight then creates a daily calorie target: Target Calories = TDEE − (Goal Loss per Week × 7700 ÷ 7). The 7700 constant approximates calories per kilogram of body fat. If the deficit would exceed TDEE, the online calorie calculator to lose weight limits it to maintain a minimum of 1200–1400 kcal for safety.
Variables used in the online calorie calculator to lose weight.
Variable
Meaning
Unit
Typical Range
weight
Current body weight
kg
35-250
height
Current height
cm
120-220
age
Age in years
years
10-100
activity
Daily activity multiplier
factor
1.2-1.9
goal
Desired weekly weight loss
kg/week
0.1-1.5
TDEE
Total Daily Energy Expenditure
kcal/day
1400-4000
Target
Suggested calorie intake
kcal/day
1200-3500
Practical Examples (Real-World Use Cases)
Example 1: A 32-year-old female, 165 cm, 70 kg, moderately active, wants to lose 0.5 kg/week. The online calorie calculator to lose weight computes BMR ≈ 1423 kcal, TDEE ≈ 2206 kcal. Daily deficit = (0.5×7700)/7 ≈ 550 kcal. Target calories ≈ 1656 kcal/day. She can expect around 0.5 kg weekly loss while preserving energy for workouts.
Example 2: A 40-year-old male, 178 cm, 90 kg, lightly active, wants to lose 1.0 kg/week. The online calorie calculator to lose weight gives BMR ≈ 1850 kcal, TDEE ≈ 2544 kcal. Daily deficit = 1100 kcal. Target calories ≈ 1444 kcal/day; because this is near the minimum, he may adjust to 1550 kcal and accept ~0.9 kg/week to maintain adherence.
How to Use This online calorie calculator to lose weight Calculator
Enter age, gender, height, weight, and select your activity level.
Set a realistic weekly loss between 0.1 and 1.5 kg; the online calorie calculator to lose weight updates instantly.
Read the primary target calories in the highlighted box and review BMR, TDEE, and deficit below.
Check the chart to compare maintenance versus target calories over weeks.
Use the projection table to track expected weekly weight; adjust if your real-world trend differs.
Copy results to keep a record or share with a nutrition coach.
Key Factors That Affect online calorie calculator to lose weight Results
Activity factor accuracy: Underestimating workouts lowers TDEE and makes the online calorie calculator to lose weight suggest too few calories.
Protein intake: Adequate protein preserves lean mass, keeping metabolic rate steadier during a calorie deficit.
Sleep quality: Poor sleep alters hormones, increasing hunger and making the online calorie calculator to lose weight harder to follow.
Non-exercise activity: Daily steps and fidgeting vary; the online calorie calculator to lose weight works best when you keep NEAT consistent.
Adaptive thermogenesis: Prolonged deficits can reduce TDEE; periodic refeeds or smaller deficits may help.
Hydration and sodium: Short-term water shifts can mask fat loss; the online calorie calculator to lose weight focuses on trends, not single weigh-ins.
Training load: Heavy lifting preserves muscle, enabling the online calorie calculator to lose weight to maintain a higher metabolic rate.
Medical factors: Thyroid status, medications, and stress can alter the calorie needs estimated by the online calorie calculator to lose weight.
Frequently Asked Questions (FAQ)
Does the online calorie calculator to lose weight guarantee weight loss? It provides a science-based target; adherence and real-world response determine results.
How often should I recalc? Update the online calorie calculator to lose weight every 4-6 weeks or after a 5% weight change.
Is 1200 kcal always safe? The online calorie calculator to lose weight floors at a cautious level, but medical supervision is advised for very low calories.
Can I use pounds and inches? Convert to metric before entering; the online calorie calculator to lose weight relies on metric for precision.
What if I plateau? Re-measure weight, steps, and sleep, then adjust activity or target loss in the online calorie calculator to lose weight.
Does muscle gain affect results? Yes, muscle maintenance keeps TDEE higher, so the online calorie calculator to lose weight may allow more calories.
Should rest days change intake? The online calorie calculator to lose weight provides a daily average; minor cycling is fine if weekly average matches.
How accurate is the deficit constant? 7700 kcal/kg is an average; the online calorie calculator to lose weight should be refined based on your weekly trend.
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var defaultValues = {age:30, gender:"female", height:165, weight:70, activity:"1.55″, goal:0.5};
function validateInputs() {
var valid = true;
valid = checkNumber("age",10,100) && valid;
valid = checkSelect("gender") && valid;
valid = checkNumber("height",120,220) && valid;
valid = checkNumber("weight",35,250) && valid;
valid = checkSelect("activity") && valid;
valid = checkNumber("goal",0.1,1.5) && valid;
return valid;
}
function checkNumber(id,min,max){
var el = document.getElementById(id);
var val = parseFloat(el.value);
var err = document.getElementById("error-"+id);
if(isNaN(val) || valmax){
err.style.display="block";
return false;
}
err.style.display="none";
return true;
}
function checkSelect(id){
var el = document.getElementById(id);
var val = el.value;
var err = document.getElementById("error-"+id);
if(val===null || val===""){
err.style.display="block";
return false;
}
err.style.display="none";
return true;
}
function calculate(){
if(!validateInputs()){
updateResults(0,0,0,0,[]);
return;
}
var age = parseFloat(document.getElementById("age").value);
var gender = document.getElementById("gender").value;
var height = parseFloat(document.getElementById("height").value);
var weight = parseFloat(document.getElementById("weight").value);
var activity = parseFloat(document.getElementById("activity").value);
var goal = parseFloat(document.getElementById("goal").value);
var bmrBase = (10*weight)+(6.25*height)-(5*age);
var bmr = gender==="male" ? bmrBase + 5 : bmrBase – 161;
var tdee = bmr * activity;
var dailyDeficit = (goal*7700)/7;
if(dailyDeficit > tdee*0.5){
dailyDeficit = tdee*0.5;
}
var target = tdee – dailyDeficit;
var minSafe = gender==="male" ? 1500 : 1200;
if(target < minSafe){
target = minSafe;
dailyDeficit = tdee – target;
}
if(target 0 ? (5/goal) : 0;
var projection = buildProjection(weight, goal, target);
updateResults(bmr, tdee, dailyDeficit, weeksToLose5kg, projection, target);
drawChart(tdee, target);
}
function buildProjection(startWeight, weeklyLoss, target){
var rows = [];
var current = startWeight;
var dailyTarget = target;
var weeks = 6;
for(var i=1;i<=weeks;i++){
current = current – weeklyLoss;
if(current 0 ? weeks.toFixed(1) : 0) + " weeks";
var tbody = document.getElementById("projectionTable");
tbody.innerHTML = "";
for(var i=0;i<projection.length;i++){
var row = projection[i];
var tr = document.createElement("tr");
var td1 = document.createElement("td");
td1.textContent = row.week;
var td2 = document.createElement("td");
td2.textContent = row.weight.toFixed(1);
var td3 = document.createElement("td");
td3.textContent = row.loss.toFixed(1);
var td4 = document.createElement("td");
td4.textContent = Math.round(row.target);
tr.appendChild(td1);tr.appendChild(td2);tr.appendChild(td3);tr.appendChild(td4);
tbody.appendChild(tr);
}
}
function resetCalc(){
document.getElementById("age").value = defaultValues.age;
document.getElementById("gender").value = defaultValues.gender;
document.getElementById("height").value = defaultValues.height;
document.getElementById("weight").value = defaultValues.weight;
document.getElementById("activity").value = defaultValues.activity;
document.getElementById("goal").value = defaultValues.goal;
calculate();
}
function copyResults(){
var text = "";
text += document.getElementById("mainResult").textContent + "\n";
text += document.getElementById("bmrResult").textContent + "\n";
text += document.getElementById("tdeeResult").textContent + "\n";
text += document.getElementById("deficitResult").textContent + "\n";
text += document.getElementById("timeResult").textContent + "\n";
text += "Assumptions: Mifflin-St Jeor, activity factor selected, deficit capped at 50% TDEE and min safe calories.";
var temp = document.createElement("textarea");
temp.value = text;
document.body.appendChild(temp);
temp.select();
temp.setSelectionRange(0, 99999);
document.execCommand("copy");
document.body.removeChild(temp);
}
function drawChart(tdee, target){
var canvas = document.getElementById("calorieChart");
if(!canvas.getContext){return;}
var ctx = canvas.getContext("2d");
ctx.clearRect(0,0,canvas.width,canvas.height);
var padding = 40;
var maxVal = Math.max(tdee, target) + 300;
var weeks = [0,1,2,3,4,5,6];
var tdeeSeries = [];
var targetSeries = [];
for(var i=0;i<weeks.length;i++){
tdeeSeries.push(tdee);
targetSeries.push(target);
}
drawAxes(ctx, padding, canvas.width, canvas.height);
drawLine(ctx, weeks, tdeeSeries, maxVal, padding, "#004a99");
drawLine(ctx, weeks, targetSeries, maxVal, padding, "#28a745");
ctx.fillStyle = "#1f2d3d";
ctx.font = "12px Arial";
ctx.fillText("Weeks", canvas.width/2 – 20, canvas.height – 8);
ctx.save();
ctx.translate(10, canvas.height/2 + 20);
ctx.rotate(-Math.PI/2);
ctx.fillText("Calories (kcal)",0,0);
ctx.restore();
}
function drawAxes(ctx, padding, width, height){
ctx.strokeStyle="#9fb3c8";
ctx.lineWidth=1;
ctx.beginPath();
ctx.moveTo(padding,padding);
ctx.lineTo(padding,height-padding);
ctx.lineTo(width-padding,height-padding);
ctx.stroke();
for(var i=0;i<=6;i++){
var x = padding + ((width-2*padding)/6)*i;
ctx.moveTo(x,height-padding);
ctx.lineTo(x,height-padding+5);
}
ctx.stroke();
}
function drawLine(ctx, xData, yData, maxVal, padding, color){
if(yData.length===0){return;}
var w = ctx.canvas.width;
var h = ctx.canvas.height;
ctx.beginPath();
for(var i=0;i<xData.length;i++){
var x = padding + ((w-2*padding)/6)*xData[i];
var y = h – padding – ((h-2*padding)*yData[i]/maxVal);
if(i===0){ctx.moveTo(x,y);}else{ctx.lineTo(x,y);}
}
ctx.strokeStyle=color;
ctx.lineWidth=2;
ctx.stroke();
ctx.fillStyle=color;
for(var j=0;j<xData.length;j++){
var px = padding + ((w-2*padding)/6)*xData[j];
var py = h – padding – ((h-2*padding)*yData[j]/maxVal);
ctx.beginPath();
ctx.arc(px,py,4,0,Math.PI*2);
ctx.fill();
}
}
calculate();