BMR Calculator

BMR (Basal Metabolic Rate) is the number of calories your body burns each day at complete rest — simply to sustain vital functions like breathing, circulation, brain activity, and cell repair. It represents your bare minimum calorie floor and forms the foundation of all daily calorie and diet calculations.

BMR is calculated using established formulas based on your age, gender, height, and weight. The most widely used is the Mifflin-St Jeor equation: For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. Our calculator uses this formula as it is considered the most accurate for the general population.

BMR is your calorie need at complete rest — if you did nothing all day. TDEE (Total Daily Energy Expenditure) is your real-world daily calorie need, calculated by multiplying your BMR by an activity factor. For example, a moderately active person uses a multiplier of 1.55×, so a BMR of 1,330 kcal becomes a TDEE of roughly 2,062 kcal/day.

The Mifflin-St Jeor equation, developed in 1990, is the most validated BMR formula for modern adults. Multiple clinical studies have confirmed it outperforms older equations like Harris-Benedict in predicting actual resting energy expenditure. This is why most reputable nutrition tools — including ours — use it as the default formula.

Choose based on your honest weekly activity pattern: Sedentary (1.2×) for desk jobs with little movement; Lightly active (1.375×) for light exercise 1–3 days/week; Moderately active (1.55×) for exercise 3–5 days/week; Very active (1.725×) for hard training 6–7 days/week; Extra active (1.9×) for physical jobs plus intense daily training. Most people overestimate their activity level — when in doubt, choose one level lower.

BMR fluctuates with age, body weight, muscle mass, hormonal changes, and overall health. After age 30, BMR tends to decline gradually as muscle mass decreases. Significant weight loss also lowers BMR — a phenomenon called metabolic adaptation — where the body becomes more frugal with calories as a survival response to prolonged deficits.

BMR alone is not the right target for weight loss — it represents the absolute minimum your body needs to function. Always start from your TDEE (maintenance calories) and create a moderate deficit of 300–500 kcal below that. Eating at or below your BMR for extended periods can trigger muscle loss, hormonal disruption, and metabolic slowdown.

Yes — this is one of the most important relationships in metabolism. Muscle tissue is metabolically active, burning roughly 3× more calories at rest than fat tissue. This is why two people with the same weight and height can have noticeably different BMRs depending on their body composition. Strength training is one of the most efficacious long-term strategies to raise your resting metabolism.

Yes. Men generally have a higher BMR than women of the same age, height, and weight — primarily because men naturally carry more muscle mass and less body fat. Hormonal differences also play a role. For example, testosterone promotes muscle retention, while estrogen is associated with higher fat storage, both of which directly influence resting calorie burn.

BMR formulas are population-level estimates with a typical margin of error of ±10%. Individual factors like gut microbiome, genetics, thyroid function, medications, sleep quality, and stress levels can cause your real BMR to deviate from the formula's output. The best approach is to use your calculated TDEE as a starting point, then adjust by 100–200 kcal based on your actual body weight trend over 2–3 weeks.