# Calorie Calculator

URL: https://speedycalculator.com/calculators/health/calorie/
Last updated: 2026-10-30

> The calorie calculator estimates how many calories you need each day to maintain your weight, and how many to eat for mild, normal or fast weight loss or gain, using the Mifflin–St Jeor, Harris–Benedict or Katch–McArdle equation and your activity level.

## Inputs

- Sex
- Age (years)
- Weight (kg, lb, st, g)
- Height (cm, in, m, ft, mm)
- BMR formula
- Body fat (Katch–McArdle) (%)
- Activity level

## Results

- BMR
- Maintain weight
- Mild weight loss (0.25 kg/week)
- Weight loss (0.5 kg/week)
- Extreme weight loss (1 kg/week)
- Mild weight gain (0.25 kg/week)
- Weight gain (0.5 kg/week)

## Formula

```
Mifflin–St Jeor: BMR = 10W + 6.25H − 5A + 5 (men) or − 161 (women)
Revised Harris–Benedict: men 88.362 + 13.397W + 4.799H − 5.677A; women 447.593 + 9.247W + 3.098H − 4.330A
Katch–McArdle: 370 + 21.6 × lean body mass
TDEE = BMR × activity multiplier   (W kg, H cm, A years)
Weight change: about 7,700 kcal per kg (3,500 kcal per lb)
```

## Explanation

A calorie target is the foundation of any weight plan. About 7,700 kcal equals 1 kg of body fat, so eating 550 kcal less than you burn each day leads to roughly 0.5 kg (1 lb) of loss a week. Very low intakes are hard to sustain and can cost muscle, so most guidelines recommend not going below about 1,200 kcal (women) or 1,500 kcal (men) without supervision.

### How to use the Calorie Calculator

- **Sex**
- **Age**
- **Weight**
- **Height**
- **BMR formula**
- **Body fat (Katch–McArdle)**
- **Activity level**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter your details, activity level and preferred formula. The calculator estimates maintenance calories and subtracts or adds the energy needed for each weekly rate of change.

### Activity multipliers

Activity levelMultiplierBasal metabolic rate (no activity)1Sedentary – little or no exercise1.2Light – exercise 1–3 times a week1.375Moderate – exercise 4–5 times a week1.465Active – daily exercise or intense 3–4 times a week1.55Very active – intense exercise 6–7 times a week1.725Extra active – very intense daily or physical job1.9

### Inputs explained

FieldWhat to enterSexChoose one: Male, FemaleAgeIn yearsWeightUnits: kg, lb, st, gHeightUnits: cm, in, m, ft, mmBMR formulaChoose one: Mifflin–St Jeor, Revised Harris–Benedict, Katch–McArdle (needs body fat)Body fat (Katch–McArdle)In %Activity levelChoose one: Basal metabolic rate (no activity), Sedentary – little or no exercise, Light – exercise 1–3 times a week, Moderate – exercise 4–5 times a week …

### What each result means

- **Maintain weight** = [BMR]×[Activity level]
- **Mild weight loss (0.25 kg/week)** = [Maintain weight] - 275
- **Weight loss (0.5 kg/week)** = [Maintain weight] - 550
- **Extreme weight loss (1 kg/week)** = [Maintain weight] - 1100
- **Mild weight gain (0.25 kg/week)** = [Maintain weight] + 275
- **Weight gain (0.5 kg/week)** = [Maintain weight] + 550

*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Sex: Male; Age: 30 years; Weight: 75 kg; Height: 178 cm; BMR formula: Mifflin–St Jeor; Activity level: Moderate – exercise 4–5 times a week.

Results — BMR = 1,718 kcal/day; **Maintain weight = 2,516 kcal/day**; Mild weight loss (0.25 kg/week) = 2,241 kcal/day; Weight loss (0.5 kg/week) = 1,966 kcal/day; Extreme weight loss (1 kg/week) = 1,416 kcal/day; Mild weight gain (0.25 kg/week) = 2,791 kcal/day; Weight gain (0.5 kg/week) = 3,066 kcal/day.

## Key terms

- **Calorie**: In nutrition, a kilocalorie (kcal): the energy to warm 1 kg of water by 1 °C.

## FAQ

**How many calories should I eat to lose weight?**
About 500 kcal less than your maintenance calories loses roughly 0.5 kg (1 lb) a week.

**Should I count calories from exercise?**
The activity level already includes them.

**Why have I stopped losing weight?**
As you lose weight your needs fall; recalculate every few kilograms.


## Sources

- [Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990](https://pubmed.ncbi.nlm.nih.gov/2305711/)
- [Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr, 1984](https://pubmed.ncbi.nlm.nih.gov/6741850/)
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy and Human Performance
- [Dietary Guidelines for Americans 2020–2025](https://www.dietaryguidelines.gov/)