BMR Calculator
Enter your age, sex, height and weight to estimate your Basal Metabolic Rate (BMR) — the calories your body uses at complete rest.
Reviewed by the ToolNestr Editorial Team — July 2026
Fill in your details to see your BMR.
About BMR
Your Basal Metabolic Rate is the foundation of any calorie or weight plan — it's how many calories you'd burn if you did nothing but rest all day. Knowing your BMR helps you understand how much you can eat to maintain, lose or gain weight once activity is added. Pair it with the Calorie Calculator to see your total daily needs, and check your BMI for a broader health picture.
⚕️ For general information only — not medical or dietary advice.
When to use this tool
Use the BMR Calculator when you're planning a weight-management strategy and need to know your baseline calorie burn. Nutrition coaches often start with BMR to build a personalised meal plan. It's also useful if you're curious how ageing or changes in body composition affect your resting metabolism — for example, comparing your BMR before and after a strength-training programme.
Tips for best results
- Weigh yourself first thing in the morning after using the bathroom for the most consistent measurements.
- Use the same scale and measuring method each time to track changes accurately over weeks and months.
- Remember that BMR is just the starting point — multiply it by an activity factor using the Calorie Calculator to get your true daily needs.
What different BMR ranges mean
BMR varies significantly by age, sex and body composition. The bars below show typical ranges for a 70 kg man and a 60 kg woman at different life stages.
Weight-conscious dieter
Know your baseline calorie burn to set a realistic daily target that supports steady, sustainable weight loss without crashing your metabolism.
Strength athlete
Track your BMR before and after a muscle-building programme to see how your increased lean mass has boosted your resting calorie burn.
Nutrition coach
Use BMR as the starting point for building personalised meal plans and teaching clients why their metabolism isn't static.
Older adult
Understand how age-related metabolic decline affects your energy needs and why strength training helps keep your BMR from dropping too fast.
| Age range | Male (70 kg, 175 cm) | Female (60 kg, 165 cm) |
|---|---|---|
| 18–25 | ~1,690 cal/day | ~1,394 cal/day |
| 26–35 | ~1,640 cal/day | ~1,344 cal/day |
| 36–45 | ~1,590 cal/day | ~1,294 cal/day |
| 46–55 | ~1,540 cal/day | ~1,244 cal/day |
| 56–65 | ~1,490 cal/day | ~1,194 cal/day |
| 66+ | ~1,440 cal/day | ~1,144 cal/day |
How BMR is calculated
BMR is estimated using the Mifflin-St Jeor equation, one of the most widely validated formulas for estimating resting energy expenditure. It uses weight, height, age and sex — the four biggest predictors of basal metabolic rate.
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
The result is in calories per day. Muscle mass, genetics and hormone levels can cause individual variation of ±200–300 cal/day from the formula's estimate.
Worked example
A 35-year-old woman who is 165 cm tall and weighs 68 kg wants to know her BMR.
How to use the BMR Calculator
Enter your details
Provide your age, sex, height and weight in either metric or imperial units. All inputs update the result instantly.
Read your BMR
Your Basal Metabolic Rate appears in calories per day — this is the energy your body needs at complete rest, before any activity.
Apply an activity factor
Multiply your BMR by your activity level (1.2–1.9) using the Calorie Calculator to estimate your total daily energy needs.
Tips for accurate BMR tracking
Build muscle to raise your BMR
Strength training is the most effective way to increase your resting metabolism. Each kilogram of muscle burns roughly 13 extra calories per day at rest.
Weigh consistently
Use the same scale at the same time of day (ideally morning, after the bathroom, before eating) for the most reliable BMR calculations over time.
Recalculate after changes
Your BMR changes with age, weight shifts and changes in muscle mass. Recalculate every 5–10 kg of weight change or whenever your body composition shifts noticeably.
Frequently asked questions
What is BMR?
Basal Metabolic Rate is the number of calories your body needs to perform basic life-sustaining functions (breathing, circulation, cell production) while at complete rest.
Which formula do you use?
We use the Mifflin-St Jeor equation, which is widely considered one of the most accurate BMR formulas for most people.
How is BMR different from daily calories?
BMR is calories at rest. Your total daily calorie need is your BMR multiplied by an activity factor — use our Calorie Calculator for that.
Does BMR change with age?
Yes — BMR naturally declines by about 1–2% per decade after age 20, mainly due to muscle loss. Strength training helps offset this decline and keep your resting metabolism higher.
Can I use my BMR to lose weight?
Yes. Once you know your BMR, you can estimate your total daily energy expenditure (TDEE) by multiplying it by an activity factor. Eating below your TDEE creates a calorie deficit for weight loss.
What factors affect my BMR?
The biggest factors are muscle mass, age, sex, and body size. People with more muscle burn more calories at rest. Genetics, hormones and thyroid function also play a role.
Can I increase my BMR?
Yes — building muscle through strength training is the most effective way. High-intensity exercise can also temporarily raise your post-exercise calorie burn. Crash dieting, on the other hand, lowers BMR.
Is BMR the same as metabolism?
Not exactly. Metabolism is the broader term for all chemical processes in your body. BMR is a specific measurement of one part of it — the calories needed to stay alive at rest.
How often should I recalculate my BMR?
Recalculate after a significant weight change (5 kg / 10 lb or more), after major changes in physical activity, or every year to account for age-related changes.
Does BMR differ between men and women?
Yes — men typically have a higher BMR because they tend to have more muscle mass and less body fat than women of the same age and weight. The Mifflin-St Jeor equation accounts for this.