Calorie Calculator
Estimate adult basal metabolic rate (BMR), maintenance calories, an adjustable calorie target and macronutrient grams. Results are planning estimates, not a diagnosis or individualized nutrition prescription.
Macronutrient conversion
Maintenance range by activity assumption
| Assumption | Multiplier | Estimated maintenance |
|---|
Formula and method
The Mifflin–St Jeor equations estimate resting energy expenditure for adults from weight W in kilograms, height H in centimeters and age A in years:
Male profile: BMR = 10W + 6.25H − 5A + 5
Female profile: BMR = 10W + 6.25H − 5A − 161
Estimated maintenance calories are BMR × activity multiplier. The target equals maintenance plus the entered daily adjustment. Macro grams use 4 kcal/g for protein, 4 kcal/g for carbohydrate and 9 kcal/g for fat.
The weekly energy equivalent divides seven times the calorie adjustment by 7,700 kcal/kg or 3,500 kcal/lb. This is a bookkeeping conversion, not a promise of body-weight change; metabolism, fluid, adherence, medication and health conditions can change outcomes.
Six checked examples
| Inputs | Checked result |
|---|---|
| Female profile, age 30, 60 kg, 165 cm | BMR = 1,320.25 kcal/day |
| Same person, light multiplier 1.375 | Maintenance = 1,815.34 kcal/day |
| Male profile, age 30, 70 kg, 175 cm, factor 1.55 | BMR = 1,648.75; maintenance = 2,555.56 kcal/day |
| Male profile, age 40, 200 lb, 5 ft 10 in | Metric conversion gives BMR ≈ 1,823.43 kcal/day |
| 2,000 kcal target with 30% protein, 40% carbohydrate, 30% fat | 150 g protein, 200 g carbohydrate, 66.67 g fat |
| Daily adjustment of −500 kcal | Weekly energy equivalent = −3,500 kcal = −1.00 lb (−0.45 kg) |
Important limits
- This calculator is for adults age 18 or older. It is not designed for children, pregnancy, lactation, eating-disorder treatment or clinical nutrition.
- BMR and activity multipliers estimate population averages. Individual energy needs can differ materially.
- The tool does not account for body composition, adaptive thermogenesis, illness, medication, disability or sport-specific training.
- A very low target, rapid intended change, symptoms or a medical condition should be discussed with a qualified clinician or registered dietitian.
- Macro percentages convert calories to grams; they do not establish individualized nutrient requirements.
Sources and further checking
- Mifflin et al., A new predictive equation for resting energy expenditure in healthy individuals.
- NIDDK Body Weight Planner for a more dynamic model and additional limitations.
Related tools: Pace Calculator, Percentage Calculator and BMI Calculator.
Questions
Is BMR the same as maintenance calories?
No. BMR estimates resting energy expenditure. Maintenance applies an activity multiplier and is therefore higher for most people.
Does a 500-calorie deficit guarantee one pound per week?
No. The 3,500 kcal/lb conversion is shown only as an energy equivalent. Real weight change is not perfectly linear.
Why does the equation ask for a profile?
The published Mifflin–St Jeor equation has two constants. The selection is an equation input, not a statement about identity.
Can I enter my own activity multiplier?
Yes. Select Custom and enter a factor from 1.0 to 3.0. Use a factor supported by your measurement method or professional guidance.
Are the macro grams a meal plan?
No. They only convert your chosen calorie percentages into grams using standard energy factors.
Body composition estimate
Calorie needs and body composition are different estimates. Use the Body Fat Calculator for circumference and BMI-based body-fat estimates, fat mass and lean mass.
Measure progress from one weight to another
A calorie estimate does not measure actual scale progress. Compare starting and current measurements with the Weight Loss Percentage Calculator, including goal progress and an optional weekly trend.