Estimate your basal metabolic rate, maintenance calories, activity-adjusted TDEE, and suggested calorie targets using your age, sex, height, weight, and activity level.
| Item | Amount |
|---|
Your basal metabolic rate (BMR) is the number of calories your body burns every single day just to stay alive — breathing, pumping blood, regulating temperature, and keeping every organ running — before you've taken a single step or eaten a single meal. It's the foundation of every calorie calculation, diet plan, and weight loss strategy that actually works. This free BMR calculator uses the scientifically validated Mifflin-St Jeor equation to give you the most accurate estimate available, then applies your activity level to show your total daily calorie burn.
BMR is the minimum number of calories your body needs to function at complete rest — no exercise, no movement, just existing. For most adults it accounts for 60%–75% of all calories burned in a day. The other 25%–40% comes from physical activity and digesting food (known as the thermic effect of food). Understanding your BMR means you finally have a real number to work with — not a generic "eat 2,000 calories" recommendation that was never tailored to you.
The Centers for Disease Control and Prevention (CDC) and most registered dietitians use BMR as the starting point for any evidence-based nutrition plan. You can learn more about calorie needs from the CDC's calorie balance guide.
There are several BMR formulas, but the Mifflin-St Jeor equation is consistently rated the most accurate for most adults by research, including a landmark study published in the Journal of the American Dietetic Association. Here's how it works:
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
In imperial units (pounds and inches): multiply weight in lbs by 0.453592 and height in inches by 2.54 before applying the formula. Our calculator handles all unit conversions automatically.
Two other formulas you may have seen are the Harris-Benedict equation (older, slightly less accurate for modern populations) and the Katch-McArdle formula, which factors in lean body mass and is preferred for athletes or anyone who has measured their body fat percentage. Our BMR Calculator offers all three.
This is one of the most searched health questions in the US — and the answer depends entirely on your goal:
The widely used activity multipliers applied to BMR are: sedentary (desk job, little exercise) × 1.2; lightly active (light exercise 1–3 days/week) × 1.375; moderately active (moderate exercise 3–5 days/week) × 1.55; very active (hard exercise 6–7 days/week) × 1.725; extra active (physical job + exercise) × 1.9.
Metabolic age compares your BMR to the average BMR of people at different ages. If your metabolic age is lower than your actual age, your metabolism is running faster than average — a good sign of fitness and muscle mass. If it's higher, your metabolism is slower than typical for your age group, which can be improved through resistance training, adequate protein intake, and better sleep.
Metabolic age is calculated by finding the age group whose average BMR matches yours most closely. It's a useful motivational marker rather than a medical diagnosis — but consistently having a metabolic age younger than your real age is associated with better long-term health outcomes. Pair this with our BMI Calculator and Body Fat Calculator for the full picture.
Your BMR is not fixed. While genetics and age play a role, these are the proven ways to raise your resting metabolic rate over time:
Build more muscle mass. Muscle tissue burns approximately 6 calories per pound per day at rest, versus fat tissue which burns roughly 2 calories per pound. Resistance training — even 2–3 sessions per week — progressively increases your BMR over months. This is the single most effective long-term strategy.
Don't crash diet. Eating too few calories (below your BMR) causes your body to downregulate metabolism — sometimes called "adaptive thermogenesis." This is why extremely low-calorie diets often stall after a few weeks. Eating at a moderate deficit (500 calories below TDEE) is more effective long-term than aggressive restriction.
Prioritise protein. The thermic effect of protein is approximately 20%–30% of calories consumed — meaning your body burns 20–30% of protein calories just digesting it. Carbohydrates have a thermic effect of about 5%–10%, and fats about 0%–3%. High protein diets naturally boost your daily calorie burn. The US Dietary Guidelines recommend 10%–35% of calories from protein.
Sleep 7–9 hours. Sleep deprivation measurably reduces BMR and increases hunger hormones (ghrelin) while reducing satiety hormones (leptin). The CDC recommends 7 or more hours of sleep per night for adults.
Don't skip meals for extended periods. Prolonged fasting beyond 24 hours triggers metabolic adaptation. Intermittent fasting (16:8 style) is generally fine and does not reduce BMR significantly, but multi-day fasting or very low calorie diets do.
The calories for weight loss formula is straightforward: one pound of body fat equals approximately 3,500 calories. To lose one pound per week, create a daily deficit of 500 calories. To lose 1.5 lbs/week, a 750-calorie daily deficit. This means:
Daily calorie target = TDEE − desired daily deficit
Example: A 35-year-old woman, 5'5", 165 lbs, lightly active. BMR ≈ 1,538 calories. TDEE (×1.375) ≈ 2,115 calories. For 1 lb/week loss: eat approximately 1,615 calories per day. For faster loss of 1.5 lbs/week: eat approximately 1,365 calories — still well above starvation levels and sustainable.
Use our BMR Calculator to get your personalised number, then pair it with our Calorie Calculator and Ideal Weight Calculator to set a realistic target.
Breastfeeding burns an additional 300–500 calories per day above your normal TDEE, depending on how much milk you're producing. For nursing mothers, the standard recommendation from the U.S. Office on Women's Health is to add approximately 330–400 calories to your daily intake to support milk production while maintaining your own energy levels. Attempting a large calorie deficit while breastfeeding is not recommended and can reduce milk supply.
BMR is what you burn at complete rest. TDEE (Total Daily Energy Expenditure) is what you actually burn in a real day — BMR plus all movement, exercise, and digestion. TDEE is always the number you plan your diet around. Think of BMR as your "engine idle speed" and TDEE as your actual fuel consumption on a typical day. Our TDEE Calculator calculates both together with your activity level already factored in.
Using this tool takes under 30 seconds. Enter your sex, age, height, and current weight. Choose your preferred unit system (metric or imperial). Select your typical activity level from the dropdown — be honest, most people overestimate this. Click Calculate. You'll instantly see your BMR, your TDEE at each activity level, your recommended daily calorie intake for weight loss, maintenance, or gain, and your metabolic age estimate.
For a complete health and nutrition picture, use these tools alongside your BMR results: Calorie Calculator — detailed daily calorie needs by goal | TDEE Calculator — total daily energy expenditure | BMI Calculator — body mass index | Ideal Weight Calculator — healthy weight range for your height | Body Fat Calculator — body composition | Macro Calculator — protein, carbs and fat targets | Calories Burned Calculator — calories burned by specific activities.
For adult women in the US, average BMR typically ranges from approximately 1,400 to 1,600 calories per day, though it varies significantly by height, weight, age, and muscle mass. A short, older, sedentary woman may have a BMR closer to 1,200; a tall, muscular younger woman may have a BMR of 1,800 or above. BMR naturally declines approximately 1%–2% per decade after age 20 as muscle mass decreases.
For adult men, average BMR typically falls between 1,700 and 2,100 calories per day. Men generally have higher BMRs than women of the same height and weight because they carry more muscle mass on average. A 6-foot, 185-pound, 35-year-old man might have a BMR of approximately 1,900 calories — meaning he burns that many calories even if he stays in bed all day.
Yes — significantly. BMR decreases by approximately 1%–2% per decade after your mid-20s, primarily because muscle mass tends to decline with age (a process called sarcopenia) unless actively maintained through resistance training. This is the biological reason why people often find it harder to maintain their weight as they get older even without changing their diet. Resistance training is the most effective intervention to slow BMR decline with age.
Yes. The most effective methods are building lean muscle through resistance training, eating adequate protein (which has a higher thermic effect than carbs or fat), getting sufficient sleep, and avoiding chronic severe calorie restriction that triggers metabolic adaptation. These changes don't happen overnight — consistent resistance training over 3–6 months produces measurable increases in resting metabolic rate.
Almost, but not exactly. BMR is measured under very strict conditions — lying completely still in a thermoneutral environment after 12+ hours of fasting. RMR is measured under less strict conditions and is typically 10%–20% higher than BMR. In practice, most "BMR calculators" — including ours — actually calculate RMR, which is more useful for real-world planning. The terms are often used interchangeably in everyday context.
This BMR calculator provides estimates for informational and educational purposes only. It is not medical advice. Individual calorie needs vary based on factors including health conditions, medications, and body composition. Always consult a registered dietitian or physician before making significant changes to your diet, especially if you have a medical condition. For personalised nutrition guidance, visit eatright.org (Academy of Nutrition and Dietetics).
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest to maintain vital functions — heartbeat, breathing, body temperature, organ function. The Mifflin-St Jeor formula is the modern standard: Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. Women: same minus 161. A 30-year-old, 5'10", 180 lb man has a BMR of ~1,800 calories/day. BMR accounts for 60–70% of total daily calorie burn.
BMR is calories burned at rest only. TDEE (Total Daily Energy Expenditure) adds the calories burned through movement: BMR × activity factor (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 athlete-level). A 1,800 BMR with moderate activity (1.55) produces a 2,790 TDEE — the maintenance calorie target. Weight loss/gain calculations always reference TDEE, not BMR.
Women have ~15% lower BMR than men of the same height/weight/age, primarily due to lower muscle mass and higher body fat percentage at the same BMI. A 30-year-old, 5'5", 140 lb woman has a BMR of ~1,360 calories/day. The Mifflin-St Jeor formula automatically applies the 161-calorie female adjustment. Pregnancy raises BMR by ~10–15% in second/third trimesters.
BMR is the absolute minimum to sustain life. Eating at BMR (without accounting for activity) creates a massive daily deficit (~800–1,200 calories below TDEE for active adults). This triggers metabolic adaptation: BMR drops, muscle is broken down for fuel, hormones (T3, leptin, testosterone) crash, and weight loss stalls. Always eat at TDEE − 300 to 500 for sustainable loss, not at BMR.
BMR drops about 1–2% per decade after age 30, primarily from age-related muscle loss. Gaining 5 lb of muscle adds ~30 calories/day to BMR; losing it removes the same. A pound of muscle burns ~6 calories/day at rest, vs 2 for a pound of fat — so resistance training is the only consistent way to raise BMR over time. Thyroid disorders (hyper/hypothyroidism) can change BMR by 15–30%.
Basal Metabolic Rate — the calories you would burn lying still for 24 hours doing nothing. Covers heartbeat, organ function, body temperature.
Mifflin-St Jeor: Men BMR = 10×kg + 6.25×cm − 5×age + 5. Women: same − 161. Accurate within 5–10% for most adults.
Eat at TDEE for maintenance. TDEE = BMR × activity factor (1.2–1.9). Never eat at BMR level — it crashes your metabolism.
Yes — drops 1–2% per decade after 30, mostly due to muscle loss. Resistance training slows this.
Yes — by adding muscle. 5 lb of new muscle adds ~30 calories/day to BMR. Cardio alone has minimal lasting BMR effect.