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> Index of every page on this site: [llms.txt](https://methodcalculator.com/llms.txt)

# **BMR Calculator**

Find out how many calories your body burns at complete rest, then see how that number changes with your activity level. Choose between three well-known equations.

## **Result**

Your basal metabolic rate

**1,649 calories/day**

**Daily calorie needs by activity level (TDEE)**

| **Activity level** | **Multiplier** | **Calories/day** |
| --- | --- | --- |
| Sedentary (little or no exercise, desk job) | × 1.2 | 1,979 |
| Lightly active (light exercise 1–3 days/week) | × 1.375 | 2,267 |
| Moderately active (moderate exercise 3–5 days/week) | × 1.55 | 2,556 |
| Very active (hard exercise 6–7 days/week) | × 1.725 | 2,844 |
| Extra active (very hard exercise and a physical job) | × 1.9 | 3,133 |

## What is basal metabolic rate?

Your basal metabolic rate (BMR) is the number of calories your body needs in 24 hours to keep its basic functions running while you are completely at rest: breathing, pumping blood, maintaining body temperature, growing and repairing cells. It accounts for roughly 60 to 75 percent of the calories most people burn in a day. Everything else comes from physical activity and the energy used to digest food.

BMR is strictly defined as a measurement taken after a night's sleep, lying down, fasted and in a neutral temperature. Because that is impractical, the equations below estimate it from your sex, age, height and weight. The closely related resting metabolic rate (RMR) is measured under looser conditions and runs a few percent higher.

## BMR formulas

**Mifflin-St Jeor (1990)**, the equation most dietitians use:

- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

**Revised Harris-Benedict (1984)**, the classic equation updated by Roza and Shizgal:

- Men: BMR = 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age
- Women: BMR = 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age

**Katch-McArdle**, which uses lean body mass instead of sex and age:

- BMR = 370 + 21.6 × lean body mass (kg), where lean mass = weight × (1 − body fat %)

**Worked example:** a 30-year-old man, 175 cm and 70 kg. Mifflin-St Jeor gives 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 700 + 1,093.75 − 150 + 5 = **1,649 calories per day**. Harris-Benedict gives about 1,696, and Katch-McArdle at 20% body fat (lean mass 56 kg) gives 370 + 21.6 × 56 = 1,580.

## From BMR to daily calories

To estimate how much you actually burn, multiply BMR by an activity factor: 1.2 for a sedentary lifestyle, 1.375 for light exercise one to three times a week, 1.55 for moderate exercise three to five times a week, 1.725 for hard daily training and 1.9 for athletes or physically demanding jobs. The table above does this for you. For the man in the example, moderate activity gives 1,649 × 1.55 ≈ 2,556 calories per day. To plan weight loss or gain from that number, use the [calorie calculator](https://methodcalculator.com/calorie-calculator).

## How to use this calculator

1. Pick your units and sex, then enter your age, height and weight.
2. Leave the formula on Mifflin-St Jeor unless you have a reason to prefer another one.
3. If you know your body fat percentage from a scan or calipers, try Katch-McArdle. You can estimate it with the [body fat calculator](https://methodcalculator.com/body-fat-calculator).
4. Read your BMR and the daily calorie needs for your activity level.

## Limitations

Prediction equations are accurate to within about 10 percent for most healthy adults, but individual metabolism varies with genetics, hormones, muscle mass, medication and illness. The formulas were developed on adults and should not be used for children, pregnant women or people with thyroid disorders without professional advice. This calculator is for information only and is not medical advice.

## **Frequently asked questions **

### **What is the difference between BMR and TDEE?**

BMR is the energy your body uses at complete rest just to stay alive: breathing, circulation, cell repair. TDEE (total daily energy expenditure) adds the calories burned by moving, exercising and digesting food. TDEE is BMR multiplied by an activity factor, and it is the number to use when planning what to eat.

### **Which BMR formula is the most accurate?**

For most adults, Mifflin-St Jeor is the most accurate of the equations that use only height, weight, age and sex, which is why the Academy of Nutrition and Dietetics recommends it. Katch-McArdle can be better for lean or very muscular people because it uses lean body mass, but only if your body fat percentage is measured accurately.

### **Can I eat fewer calories than my BMR to lose weight faster?**

Eating below your BMR for long periods is not recommended without medical supervision. Very low intakes make it hard to get enough protein, vitamins and minerals, can cause muscle loss and tend to be impossible to sustain. A deficit of 500 calories below your TDEE is the usual guideline.

### **Why does my BMR go down as I age?**

Muscle is metabolically active tissue, and adults tend to lose muscle from their 30s onward unless they do resistance training. Hormonal changes also play a role. The formulas account for this with the age term, which lowers the result by roughly 5 to 7 calories per year.

## **Related calculators **

- [**Calorie Calculator**](https://methodcalculator.com/calorie-calculator)
- [**BMI Calculator**](https://methodcalculator.com/bmi-calculator)
- [**Macro Calculator**](https://methodcalculator.com/macro-calculator)
- [**Body Fat Calculator**](https://methodcalculator.com/body-fat-calculator)

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