onlinecalculator.me

Free online calorie calculator

Calories are the energy your body gets from food. This calculator estimates how many you need each day to maintain, lose, or gain weight at your activity level.

Units
BMR
— kcal
Resting metabolic rate
TDEE
— kcal
Total daily energy expenditure
Daily target
— kcal
Suggested macros (30/40/30 split)
—
Protein (g)
—
Carbs (g)
—
Fat (g)
About this calculator

How to use

  1. Choose Imperial or Metric.
  2. Enter sex, age, weight, and height.
  3. Select your activity level.
  4. Set a weekly weight goal (lose, maintain, or gain).
  5. Read your BMR, TDEE, calorie target, and macros.

The formula

Mifflin-St Jeor BMR (1990):

Men:   BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161

Where W = weight in kg, H = height in cm, A = age in years.

TDEE:

TDEE = BMR × activity multiplier

Activity multipliers: Sedentary 1.2 · Light 1.375 · Moderate 1.55 · Active 1.725 · Extra 1.9

Calorie target:

Target = TDEE + (goal lb/week × 500)

Minimum safe floors: 1,200 kcal/day (women), 1,500 kcal/day (men).

Worked example

Female, 30 years, 135 lb (61.2 kg), 5 ft 5 in (165 cm), moderately active, wants to lose 1 lb/week:

  • BMR ≈ 1,378 kcal
  • TDEE ≈ 1,378 × 1.55 ≈ 2,136 kcal
  • Target: 2,136 − 500 = 1,636 kcal/day
  • Macros: ~123g protein, ~164g carbs, ~55g fat

Notes

  • Source: Mifflin MD, et al. Am J Clin Nutr. 1990;51(2):241-247.
  • These are estimates. Individual metabolism, hormones, and muscle mass all affect actual needs.
  • Consult a registered dietitian for medical nutrition advice.

Frequently asked

What formula does this calculator use?
The Mifflin-St Jeor equation, published in 1990 in the American Journal of Clinical Nutrition and widely considered the most accurate for most adults. Men: BMR = 10W + 6.25H − 5A + 5. Women: BMR = 10W + 6.25H − 5A − 161 (W = kg, H = cm, A = age in years).
What is BMR and how does it relate to daily calorie needs?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest. Multiply by an activity factor to get TDEE (Total Daily Energy Expenditure) — the calories needed to maintain your current weight.
How many calories should I cut to lose a pound a week?
A common guideline: 1 lb of body fat ≈ 3,500 calories, so a deficit of 500 kcal/day produces roughly 1 lb/week of loss. The calculator enforces a minimum of 1,200 kcal/day (women) or 1,500 kcal/day (men) to avoid unsafe restriction.
What is the macro split used?
The suggested macro split is 30% protein, 40% carbohydrates, and 30% fat — a balanced moderate-protein split suitable for general fitness. Adjust based on your specific goals.
How accurate are these estimates?
Mifflin-St Jeor predicts BMR within about ±10% for most adults. Individual metabolism varies. Use the output as a starting point, then track actual intake and weight change for two weeks and adjust.