Use this BMR Calculator to estimate your basal metabolic rate—how many calories your body burns at rest. It uses your age, sex, height, and weight to estimate daily calorie needs, helping you plan smarter meals and training.
- Step 1: Enter your sex.
- Step 2: Add your age (years).
- Step 3: Enter height and weight using your preferred units.
- Step 4: Click Calculate to see your estimated BMR in kcal/day.
- Step 5 (optional): Use the activity level to estimate TDEE (total daily energy expenditure).
What Is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body needs to function at rest. Think of it as the energy required to keep vital processes going—like breathing, circulation, and cell repair.
BMR is not your total daily calories. It’s a baseline. To estimate your day-to-day needs, you typically multiply BMR by an activity factor to get TDEE (Total Daily Energy Expenditure).
The Math Behind a BMR Calculator
Most BMR calculators use validated equations that approximate how body composition and age influence metabolism. A common choice is the Mifflin–St Jeor formula because it performs well across many adult populations.
Mifflin–St Jeor Formula
Depending on sex, the equation is:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
What the variables mean
| Variable | Meaning | Typical unit |
|---|---|---|
| Weight | Your body mass | kg |
| Height | Your stature | cm |
| Age | Metabolic changes over time | years |
How Unit Conversions Work
If you enter height in inches and weight in pounds, the calculator converts them to the metric units required by the formula.
- Pounds (lb) → kilograms (kg): kg = lb ÷ 2.20462
- Inches (in) → centimeters (cm): cm = in × 2.54
This means you can use whichever measurement system is easiest without changing the underlying math.
From BMR to Daily Calories (TDEE)
Your BMR is only part of the story. To estimate your total daily calorie needs, multiply BMR by an activity factor. This accounts for movement beyond resting energy use.
In the calculator, you can choose an activity level such as:
- Sedentary (little exercise): ~1.2
- Lightly active (light exercise): ~1.375
- Moderately active (moderate exercise): ~1.55
- Very active (hard training): ~1.725
- Extra active (very hard/physical job): ~1.9
Remember: activity levels are estimates. Your real TDEE can vary based on sleep, stress, and how consistently you move throughout the day.
How to Use Your Results
Once you have your BMR (and optionally TDEE), you can make more informed decisions. The key is to use the number as a starting point, then adjust based on real-world results.
- Fat loss: Create a calorie deficit (often 10–25% below TDEE) and monitor progress.
- Maintenance: Aim near TDEE and track your weight trends over 2–4 weeks.
- Muscle gain: Consider a small surplus (often 5–15% above TDEE) alongside resistance training.
If your weight doesn’t move as expected, adjust calories gradually rather than making big jumps.
Practical Examples
Example 1: Planning a fat-loss target
Say your BMR is estimated at 1,450 kcal/day and your TDEE at 2,175 kcal/day (moderately active). A moderate deficit of ~15% puts you around 1,850 kcal/day. Track weekly averages to confirm the trend.
Example 2: Training consistency and maintenance
If your BMR comes out to 1,600 kcal/day and TDEE to 2,400 kcal/day (lightly active), you can use ~2,400 as a maintenance baseline. If you gain steadily, reduce slightly; if you lose steadily, increase slightly.
Frequently Asked Questions
How accurate is a BMR Calculator?
BMR calculators are estimates, not medical measurements. Equations like Mifflin–St Jeor are widely used and generally reasonable for adults, but individual metabolism varies. For best results, treat your BMR/TDEE as a starting point and adjust calories based on weight trends over several weeks.
Is BMR the same as calories burned in a day?
No. BMR is the energy you burn at rest, while TDEE includes activity, movement, and daily routines. Many people use BMR to estimate TDEE by applying an activity factor. Your actual daily burn can differ due to steps, workouts, sleep, and stress levels.
Should I use BMR or TDEE for weight loss?
For weight loss, TDEE is usually the better target because it reflects your total daily energy needs. A calorie deficit below TDEE supports fat loss. If you only use BMR, you’ll likely underestimate your daily burn and may create a deficit that’s too small or too large.
What if my results feel too high or too low?
If your estimated needs don’t match your results, don’t panic. People often misjudge activity level or underestimate daily movement. Adjust your calories by 100–250 kcal/day and re-check trends over 2–4 weeks. Consistency matters more than perfection.
Does age or sex affect BMR?
Yes. BMR typically declines with age due to changes in body composition and metabolic activity. Sex differences are included in standard formulas because average body composition differs between men and women. Still, individual variation is significant, so track and refine your targets.