How to Use the Calorie Calculator
A short path from your stats to an estimated daily energy need.
- Choose Metric (cm, kg) or Imperial (ft, in, lb). Switching units converts values you already entered.
- Select the sex used in the formula, then enter age, height, and weight.
- Pick an activity level that matches a typical week. Results update live — no submit button.
- Read estimated maintenance calories (TDEE), BMR, and the comparison table. Optionally open “Adjusting for a goal” for a gradual range with safety floors.
BMR vs. TDEE
Two related estimates — rest versus a full day of activity.
BMR (basal metabolic rate) estimates the energy your body uses at rest to support basic functions. It is the foundation of most daily calorie calculators.
TDEE (total daily energy expenditure) multiplies BMR by an activity factor so the estimate includes everyday movement and exercise. The large number on this page — estimated maintenance calories — is your TDEE for the activity level you selected.
How Your Calorie Needs Are Calculated
This tool uses the Mifflin–St Jeor equation, then applies an activity multiplier.
Male: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Female: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Then TDEE = BMR × activity multiplier. Example: a 30-year-old using the male formula at 70 kg and 175 cm has BMR ≈ 1,649 kcal/day; at moderate activity (×1.55) TDEE ≈ 2,560 kcal/day when rounded to the nearest 10.
| Activity level | Multiplier |
|---|---|
| SedentaryLittle or no exercise | ×1.2 |
| Lightly activeLight exercise 1 to 3 days a week | ×1.375 |
| Moderately activeExercise 3 to 5 days a week | ×1.55 |
| Very activeHard exercise 6 to 7 days a week | ×1.725 |
| Extra activeVery hard exercise or a physical job | ×1.9 |
How Accurate Is This Estimate?
Honest limits of a population-based calorie calculator.
Equations like Mifflin–St Jeor describe average patterns across large groups. Your real needs can differ because of body composition, genetics, medications, health conditions, sleep, and how much you move outside formal exercise.
The best use of a daily calorie calculator is as a starting point. Notice how you feel and what changes over time, and talk with a healthcare professional or registered dietitian before making large changes — especially if you have a medical condition, are pregnant or breastfeeding, or are under 18.
Frequently Asked Questions
Maintenance calories, BMR vs TDEE, activity levels, and safety.
How many calories should I eat a day?
It depends on your age, sex, height, weight, and how active you are. This calorie calculator estimates maintenance calories (TDEE) from your basal metabolic rate and activity level. Treat the number as a starting point, not an exact prescription, and adjust with guidance from a healthcare professional if needed.
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) estimates the energy your body uses at rest. TDEE (total daily energy expenditure) multiplies BMR by an activity factor to estimate the energy you use across a typical day, including movement and exercise. Maintenance calories on this page are your estimated TDEE.
What are maintenance calories?
Maintenance calories are an estimate of how much energy you need each day to keep your current weight roughly steady, assuming your activity stays similar. Eating notably more or less than that estimate over time can change weight for many people, but individual responses vary.
Which activity level should I choose?
Pick the description that best matches a typical week. If you are unsure, choose the lower option — people often overestimate how active they are. You can also compare estimated maintenance calories across all activity levels in the results table.
How accurate is the Mifflin-St Jeor equation?
Mifflin–St Jeor is a widely used population equation for resting energy needs. Studies suggest many people’s measured resting values fall within roughly 10% of the prediction, but body composition, genetics, medications, health conditions, and daily movement still cause real-world differences. Use the result as an estimate to refine over time.
Why does this calculator ask for sex?
The Mifflin–St Jeor equation uses different constants for the male and female formulas (plus 5 versus minus 161). That is why the field is labeled “Sex used in the formula” — it changes the math, not a social category beyond the equation’s design.
Can I use this calculator if I am pregnant, breastfeeding, under 18, or have a medical condition?
No. This tool is for adults aged 18 and over and is not intended for pregnancy, breastfeeding, or people whose metabolism is affected by a medical condition. Please ask a healthcare professional or registered dietitian for personal guidance.
Is it safe to eat below the estimated calories?
Very low daily intakes are generally not recommended without medical supervision. This calculator will not show a goal estimate below 1,200 kcal/day for the Female formula setting or 1,500 kcal/day for the Male setting. If you have questions about energy intake, talk to a doctor or registered dietitian.
Sources
Mifflin–St Jeor equation: Mifflin et al., Am J Clin Nutr (1990) on PubMed. General information on calories and average daily energy needs: NHS — Understanding calories.
This calculator provides general information and is not medical or nutritional advice. Talk to a qualified healthcare professional or registered dietitian about your diet.
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