# 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.

Estimate daily calorie needs using the Mifflin-St Jeor BMR formula with your activity level and weight goal. Includes macro breakdown for protein, carbs, and fat.

**Interactive version:** https://onlinecalculator.me/health/calorie/
**Category:** Health

## 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 questions

### 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.

## Sources

- [Basal metabolic rate](https://en.wikipedia.org/wiki/Basal_metabolic_rate) — Wikipedia
- [Harris–Benedict equation (with Mifflin–St Jeor revision)](https://en.wikipedia.org/wiki/Harris%E2%80%93Benedict_equation) — Wikipedia

## Related calculators

- [BMR calculator](https://onlinecalculator.me/health/bmr/) — Compare three BMR formulas — Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle.
- [TDEE calculator](https://onlinecalculator.me/health/tdee/) — Compute total daily energy expenditure from any BMR value.
- [BMI calculator](https://onlinecalculator.me/health/bmi/) — Body mass index from height and weight with CDC weight categories.
- [Pregnancy due date calculator](https://onlinecalculator.me/health/pregnancy/) — Estimate due date from last menstrual period or conception date.

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