Weight Loss Calorie Calculator for Precise Daily Targets
Use this weight loss calorie calculator to set an evidence-based daily calorie goal, understand your basal metabolic rate (BMR), total daily energy expenditure (TDEE), and the deficit needed to reach your goal weight safely. The tool recalculates instantly as you adjust age, weight, height, activity, goal weight, and timeframe.
Weight Loss Calorie Calculator
Realistic range 35–250 kg. Enter current body weight.
The weight loss calorie calculator uses the Mifflin-St Jeor equation for BMR, multiplies by your activity factor to get TDEE, and subtracts the daily calorie deficit required to reach your goal within the chosen weeks. Results are capped for safety.
Weekly projection based on your weight loss calorie calculator inputs
Week
Projected Weight (kg)
Daily Calorie Target (kcal)
Cumulative Change (kg)
Projected trend: weight vs. calorie target
Projected Weight (kg)Calorie Target (kcal)
What is a weight loss calorie calculator?
A weight loss calorie calculator estimates how many calories you should eat each day to move from your current weight to your goal weight safely. It blends basal metabolic rate, activity level, and a planned calorie deficit to create a personalized target. Anyone seeking structured fat loss, from busy professionals to athletes refining weight classes, can use a weight loss calorie calculator to keep daily decisions grounded in math rather than guesswork.
Common misconceptions include thinking all deficits are equal, assuming extreme restriction speeds results without downsides, or believing activity alone replaces dietary control. A precise weight loss calorie calculator shows why a balanced deficit paired with realistic timeframes is more sustainable.
Weight loss calorie calculator formula and mathematical explanation
The weight loss calorie calculator starts with BMR via Mifflin-St Jeor: for males, BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5; for females, subtract 161 instead of adding 5. TDEE multiplies BMR by an activity factor. The required daily deficit equals total fat to lose (in kg) × 7700 kcal divided by total days. The calorie target is TDEE minus that deficit, bounded to avoid unsafe intake.
Variables table
Variables used in the weight loss calorie calculator
Variable
Meaning
Unit
Typical Range
Weight
Current body mass
kg
35–250
Height
Stature for BMR
cm
120–230
Age
Years old
years
14–90
Activity factor
Movement multiplier
none
1.2–1.9
Goal weight
Target body mass
kg
35–250
Timeframe
Duration to goal
weeks
1–52
Calorie target
Daily intake aim
kcal/day
1200–4000+
Practical examples (real-world use cases)
Example 1: A 35-year-old male at 88 kg, 180 cm, moderate activity (1.55), aiming for 78 kg in 20 weeks. The weight loss calorie calculator yields BMR ≈ 1790 kcal, TDEE ≈ 2770 kcal, total loss 10 kg = 77,000 kcal. Daily deficit ≈ 550 kcal, producing a calorie target near 2220 kcal/day and a weekly change of about 0.7 kg, aligned with safe pacing.
Example 2: A 42-year-old female at 72 kg, 165 cm, light activity (1.375), targeting 65 kg in 16 weeks. The weight loss calorie calculator shows BMR ≈ 1440 kcal, TDEE ≈ 1980 kcal, total loss 7 kg = 53,900 kcal. Daily deficit ≈ 480 kcal, giving a calorie target around 1500 kcal/day and a weekly loss near 0.44 kg, balancing adherence and metabolism.
How to use this weight loss calorie calculator
Enter weight, height, age, biological sex, activity, goal weight, and timeframe. The weight loss calorie calculator recalculates instantly. Read the highlighted daily calorie target first, then review BMR and TDEE to understand maintenance level. The deficit line shows how aggressively you are dieting; if it exceeds 1000 kcal/day, consider extending the timeframe. Use the weekly projection table to visualize your expected trend and adjust inputs until the plan matches your lifestyle.
When results are clear, copy them with the button to keep in your notes or meal plan. Revisit the weight loss calorie calculator weekly as your weight changes to keep targets accurate.
Key factors that affect weight loss calorie calculator results
Metabolic rate: Lower BMR from age or smaller body size reduces TDEE, requiring tighter calorie control.
Activity selection: Higher activity factors expand your calorie target; a mismatch inflates or underestimates the plan.
Timeframe length: Short windows demand larger deficits; extending the timeframe lowers daily restriction and improves adherence.
Non-exercise activity (NEAT): Steps, posture, and daily movement can shift TDEE more than short workouts.
Adaptive thermogenesis: Prolonged deficits can reduce expenditure; recalibrate the weight loss calorie calculator every few weeks.
Macronutrient mix: Protein preserves lean mass, allowing the same calorie target to deliver better body composition.
Sleep and stress: Hormonal shifts can alter hunger and NEAT, affecting real-world outcomes versus the calculated target.
Diet costs: Planning with a calorie deficit guide linked meal plan helps avoid overspending on convenience foods.
Frequently asked questions (FAQ)
How accurate is the weight loss calorie calculator? It provides an evidence-based starting point using BMR and activity; real results depend on adherence and metabolism.
Can I use pounds and inches? Convert to kilograms and centimeters for best accuracy; 1 kg = 2.20462 lb, 1 inch = 2.54 cm.
What is a safe daily deficit? Most people should stay within 300–800 kcal/day; the weight loss calorie calculator caps extremes automatically.
Why did my progress stall? Weight fluctuations, water shifts, and lowered NEAT can hide fat loss; re-measure inputs and check activity honesty.
Should I change the plan after each kilogram lost? Re-run the weight loss calorie calculator every 2–3 kg lost to keep TDEE precise.
Does activity factor include workouts? Yes, select the factor that reflects both daily movement and structured exercise.
What if the target is below 1200 kcal? Extend the timeframe or raise activity; very low intake is unsustainable.
Can I plan for muscle gain after fat loss? Switch goal weight upward and allow a surplus; the same calculator math guides a lean bulk.
fitness budgeting – Control grocery and training spend while dieting.
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var chartData = {weights:[], calories:[]};
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if(value===""||isNaN(value)){return "Enter a valid number.";}
var num=parseFloat(value);
if(nummax){return "Value must be no more than "+max+".";}
return "";
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function getInputs(){
var weight=document.getElementById("weight").value;
var height=document.getElementById("height").value;
var age=document.getElementById("age").value;
var sex=document.getElementById("sex").value;
var activity=document.getElementById("activity").value;
var goalWeight=document.getElementById("goalWeight").value;
var timeframe=document.getElementById("timeframe").value;
document.getElementById("err-weight").innerText=validateNumber(weight,35,250);
document.getElementById("err-height").innerText=validateNumber(height,120,230);
document.getElementById("err-age").innerText=validateNumber(age,14,90);
document.getElementById("err-sex").innerText="";
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height:parseFloat(height),
age:parseFloat(age),
sex:sex,
activity:parseFloat(activity),
goalWeight:parseFloat(goalWeight),
timeframe:parseInt(timeframe,10)
};
}
function calculateAll(){
var inputs=getInputs();
if(!inputs){return;}
var bmr=0;
if(inputs.sex==="male"){
bmr=10*inputs.weight+6.25*inputs.height-5*inputs.age+5;
}else{
bmr=10*inputs.weight+6.25*inputs.height-5*inputs.age-161;
}
var tdee=bmr*inputs.activity;
var totalLossKg=inputs.weight-inputs.goalWeight;
var days=inputs.timeframe*7;
var dailyDeficit=0;
var weeklyChange=0;
if(totalLossKg>0){
dailyDeficit=(totalLossKg*7700)/days;
weeklyChange=totalLossKg/inputs.timeframe;
}else if(totalLossKg1100){dailyDeficit=1100;}
if(dailyDeficit<-800){dailyDeficit=-800;}
var calorieTarget=tdee-dailyDeficit;
if(calorieTarget5000){calorieTarget=5000;}
updateResults(calorieTarget,bmr,tdee,dailyDeficit,weeklyChange,inputs);
buildTable(inputs,calorieTarget,dailyDeficit,tdee);
updateChart();
}
function updateResults(calorieTarget,bmr,tdee,dailyDeficit,weeklyChange,inputs){
document.getElementById("primaryResult").innerText="Daily calorie target: "+Math.round(calorieTarget)+" kcal";
document.getElementById("bmrResult").innerText=Math.round(bmr)+" kcal/day";
document.getElementById("tdeeResult").innerText=Math.round(tdee)+" kcal/day";
var deficitText=Math.round(dailyDeficit);
if(dailyDeficit<0){deficitText=Math.round(Math.abs(dailyDeficit))+" kcal surplus";}
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document.getElementById("deficitResult").innerText=deficitText;
document.getElementById("weeklyChange").innerText=weeklyChange.toFixed(2)+" kg/week";
document.getElementById("explainerText").innerText="This weight loss calorie calculator combines your BMR ("+Math.round(bmr)+" kcal) and activity factor to reach a TDEE of "+Math.round(tdee)+" kcal. To move from "+inputs.weight+" kg to "+inputs.goalWeight+" kg in "+inputs.timeframe+" weeks, it applies a daily adjustment of "+deficitText+".";
}
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tbody.innerHTML="";
chartData.weights=[];
chartData.calories=[];
var currentWeight=inputs.weight;
var weeklyCalorieTarget=calorieTarget;
var weeklyDelta=(dailyDeficit*7)/7700;
var cumulative=0;
var weeks=Math.max(1,inputs.timeframe);
var i=0;
for(i=0;i<=weeks;i++){
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function resetDefaults(){
document.getElementById("weight").value=80;
document.getElementById("height").value=175;
document.getElementById("age").value=35;
document.getElementById("sex").value="male";
document.getElementById("activity").value="1.55";
document.getElementById("goalWeight").value=72;
document.getElementById("timeframe").value=16;
calculateAll();
}
function copyResults(){
var primary=document.getElementById("primaryResult").innerText;
var bmr=document.getElementById("bmrResult").innerText;
var tdee=document.getElementById("tdeeResult").innerText;
var deficit=document.getElementById("deficitResult").innerText;
var weekly=document.getElementById("weeklyChange").innerText;
var text="Weight Loss Calorie Calculator Results:\n"+primary+"\nBMR: "+bmr+"\nTDEE: "+tdee+"\nDeficit: "+deficit+"\nWeekly change: "+weekly+"\nAssumptions: Mifflin-St Jeor, activity multiplier, fat energy density 7700 kcal/kg.";
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ctx.clearRect(0,0,canvas.width,canvas.height);
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var width=canvas.width-padding*2;
var height=canvas.height-padding*2;
var maxWeight=Math.max.apply(null,chartData.weights);
var minWeight=Math.min.apply(null,chartData.weights);
var maxCal=Math.max.apply(null,chartData.calories);
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ctx.save();
ctx.translate(14,canvas.height/2);
ctx.rotate(-Math.PI/2);
ctx.fillText("Weight (kg) / Calories (x1000)",0,0);
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window.onload=function(){
calculateAll();
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