BMR Calculator
Calculate your Basal Metabolic Rate — the calories you burn just to stay alive at rest.
This tool provides general estimates for informational purposes only and is not a substitute for personalized medical or nutritional advice.
| Age | Male BMR | Female BMR |
|---|---|---|
| 20 | 1,668 cal | 1,502 cal |
| 25 | 1,643 cal | 1,477 cal |
| 30 | 1,618 cal | 1,452 cal |
| 35 | 1,593 cal | 1,427 cal |
| 40 | 1,568 cal | 1,402 cal |
| 45 | 1,543 cal | 1,377 cal |
| 50 | 1,518 cal | 1,352 cal |
| 55 | 1,493 cal | 1,327 cal |
| 60 | 1,468 cal | 1,302 cal |
| 65 | 1,443 cal | 1,277 cal |
Frequently asked questions
What is BMR?
Basal Metabolic Rate is the number of calories your body needs to maintain basic life functions — breathing, circulation, cell production — while completely at rest, not accounting for any activity.
How is BMR calculated here?
We use the Mifflin-St Jeor equation, generally considered one of the more accurate formulas for estimating BMR from age, sex, height, and weight.
How is BMR different from calorie needs?
BMR is just your resting energy use. Your actual daily calorie needs (TDEE) are higher, since they add in calories burned through daily activity and exercise on top of BMR.
Can I lose weight eating at my BMR?
Eating below your BMR for extended periods generally isn't recommended, since it may not provide enough energy for essential body functions. A moderate deficit below your full daily calorie needs (TDEE) is the more commonly recommended approach.
What is a normal BMR for a 30-year-old?
For someone 170cm tall and 70kg, this calculator estimates a BMR of about 1,618 calories/day for men and 1,452 calories/day for women at age 30. See the chart above for other ages.
Does BMR decrease with age?
Yes — this calculator's formula reduces BMR by about 5 calories per year of age, holding height and weight constant, reflecting the gradual decline in resting metabolism as we get older.
Why is BMR lower for women than men at the same height and weight?
The Mifflin-St Jeor equation applies a fixed offset — adding 5 for men and subtracting 161 for women — reflecting average differences in body composition, resulting in roughly 166 fewer calories per day for women at the same height, weight, and age.
What is the difference between BMR and RMR?
BMR is measured under strict conditions, such as after fasting and full rest, while resting metabolic rate (RMR) is measured under looser conditions and is usually slightly higher. Online calculators, including this one, give an estimate that is used for either in practice.
How accurate is a BMR calculator?
The Mifflin-St Jeor equation is widely used and is often close to measured values for many adults, but it only uses age, sex, height and weight. It cannot see your muscle mass, genetics or health conditions, so treat the result as a starting estimate.
Can I increase my BMR?
Only modestly. Building muscle raises resting energy use a little, because muscle uses more energy than fat at rest, but the effect is small compared with the calories you burn through daily activity. Be cautious of products that claim to speed up metabolism dramatically.
About this tool
This calculator estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation — the calories your body burns just to maintain basic functions at complete rest. It's a useful building block for understanding your overall daily calorie needs.
Worked example
The calculator uses the Mifflin-St Jeor equation. For men it is 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5, and for women the last term is − 161 instead of + 5. If you enter imperial units, they are converted to kilograms and centimetres first.
Woman, 30, 165 cm, 60 kg: 10 × 60 = 600, 6.25 × 165 = 1,031.25 and 5 × 30 = 150. So 600 + 1,031.25 − 150 − 161 = 1,320.25, or about 1,320 calories a day at rest.
Man, 40, 180 cm, 80 kg: 10 × 80 = 800, 6.25 × 180 = 1,125 and 5 × 40 = 200. So 800 + 1,125 − 200 + 5 = 1,730, or about 1,730 calories a day at rest.
From BMR to daily calorie needs
BMR is only the energy your body uses at rest. To estimate your total daily energy use (TDEE), multiply your BMR by an activity factor. These are commonly used estimates, shown here for the 1,320-calorie example above:
| Activity level | Multiplier | Estimated daily calories |
|---|---|---|
| Sedentary (little or no exercise) | x 1.2 | 1,584 cal |
| Lightly active (light exercise 1 to 3 days a week) | x 1.375 | 1,815 cal |
| Moderately active (moderate exercise 3 to 5 days a week) | x 1.55 | 2,046 cal |
| Very active (hard exercise 6 to 7 days a week) | x 1.725 | 2,277 cal |
| Extra active (very hard exercise or a physical job) | x 1.9 | 2,508 cal |
For a quicker route, use the TDEE calculator, or the calorie calculator to see estimates for losing, maintaining or gaining weight.
What affects your BMR
- Body size. Larger bodies use more energy at rest, which is why weight and height are in the formula.
- Age. Resting energy use tends to fall gradually with age, and the equation reflects this with a fixed reduction for each year.
- Sex. On average men have more lean mass than women of the same height and weight, which the equation reflects with a different fixed offset.
- Muscle mass. Muscle uses more energy at rest than fat. This calculator does not ask for body composition, so two people with the same inputs but different muscle mass can have different real BMRs.
- Other factors. Genetics, hormones and some medical conditions can also change resting energy use, and no online formula can account for them.
Getting the most useful result
- Use your current weight and re-check the result after a significant weight change.
- Treat it as an estimate. Formulas like this are usually close for many adults but can be off for individuals, so watch how your body responds over a few weeks.
- Do not use BMR as a calorie target. Your daily needs are higher once activity is included, so work from TDEE instead.
- Speak to a doctor or dietitian before making big changes to how you eat, especially if you have a medical condition.