How Many Calories Does Your Body Burn at Rest?
Enter your sex, weight, height, and age to calculate your Basal Metabolic Rate using the Mifflin-St Jeor formula — and see your calorie needs at every activity level.
Your BMR accounts for 60–75% of all calories you burn daily — even on a rest day.
60–75%
of total daily calorie burn comes from BMR — even at rest
×1.55
activity multiplier for someone exercising 3–5 days per week (moderate)
500 kcal
daily deficit needed to lose approximately 1 lb per week
Understanding your metabolism
BMR vs TDEE: which number to use
BMR is the absolute minimum calories to survive. TDEE is what you actually need day-to-day. For weight management, use TDEE as your baseline: eat below it to lose weight, above it to gain. Never sustain a calorie intake below BMR — it risks muscle catabolism and metabolic slowdown over time.
Muscle raises your BMR
Muscle tissue is metabolically expensive — it burns roughly 6–10 kcal per pound per day at rest, compared to fat tissue at 2–3 kcal. Adding 5 lbs of lean muscle raises BMR by 30–50 kcal/day — not dramatic, but meaningful over years. Resistance training raises BMR both directly (muscle mass) and indirectly (post-exercise calorie burn lasting 24–72 hours).
Adjust every 5–10 lbs
As your weight changes, your BMR changes too. Recalculate every time you gain or lose 5–10 lbs to keep your calorie target accurate. Failing to update leads to a stall — your deficit shrinks as you get lighter, and without recalculation you unknowingly return to maintenance calories without realising it.
BMR and moderate maintenance calories by age (male: 75 kg, 175 cm | female: 65 kg, 165 cm)
Your Basal Metabolic Rate is the number of calories your body burns at complete rest just to keep you alive — powering your heart, brain, liver, kidneys, and temperature regulation. It accounts for 60–75% of total daily calorie burn, which is why cutting calories aggressively and slashing activity isn't as effective as it seems — your BMR adapts downward. The table below uses the Mifflin-St Jeor equation, the most clinically validated formula for non-athletes.
| Age | Male BMR | Male moderate TDEE | Female BMR | Female moderate TDEE |
|---|---|---|---|---|
| 20 years | 1819 kcal | 2819 kcal | 1473 kcal | 2283 kcal |
| 25 years | 1791 kcal | 2776 kcal | 1452 kcal | 2251 kcal |
| 30 years | 1763 kcal | 2733 kcal | 1430 kcal | 2217 kcal |
| 40 years | 1706 kcal | 2644 kcal | 1387 kcal | 2150 kcal |
| 50 years | 1649 kcal | 2556 kcal | 1343 kcal | 2082 kcal |
| 60 years | 1592 kcal | 2468 kcal | 1300 kcal | 2015 kcal |
What is a normal BMR for men and women?
For a 35-year-old at average height and weight: men average 1,700–1,900 kcal/day BMR; women average 1,400–1,600 kcal/day. BMR peaks in your 20s and declines roughly 1–2% per decade thereafter, partly due to muscle mass loss. Two people of identical age, height, and weight can have BMRs that differ by 200–300 kcal/day based on body composition.
What is the difference between BMR and TDEE?
BMR is calories burned at total rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), extremely active (×1.9). A woman with a BMR of 1,450 who exercises 3–4 days/week has a TDEE of roughly 2,250 — the calories she needs to maintain weight.
Which BMR formula is most accurate — Mifflin-St Jeor or Harris-Benedict?
Mifflin-St Jeor (1990) is more accurate for modern populations — studies show it predicts measured BMR within 10% for about 82% of people. The original Harris-Benedict (1919) tends to overestimate by 5–15%, particularly for overweight individuals. For athletes with high muscle mass, the Katch-McArdle formula (which uses lean body mass) is most precise.
How the BMR Calculator Works
Formula
Male BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5\nFemale BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161This calculator uses the Mifflin-St Jeor equation (1990), the most widely validated BMR formula for adults. Enter weight in kilograms, height in centimetres, and age in years.
The BMR result is then multiplied by standard activity factors: ×1.2 (sedentary), ×1.55 (moderately active), and ×1.725 (very active) to estimate Total Daily Energy Expenditure at each level.