You enter your age, sex, height, weight, and activity level. The tool converts your measurements to metric, then applies the Mifflin-St Jeor equation to estimate BMR. It multiplies BMR by a standard activity factor (1.2 for sedentary through 1.9 for extremely active) to produce your TDEE. The formula assumes typical body composition and does not account for unusually high or low muscle mass.
Be honest about your typical week, not your best week. "Moderately active" fits most people who exercise 3–5 days. If your job involves sitting all day and you only train 1–2 times a week, "lightly active" is more accurate.
Research generally shows Mifflin-St Jeor is more accurate for most adults, especially people of healthy weight. Harris-Benedict tends to overestimate by about 5%. Both are estimates — real-world needs vary.
A deficit of 300–500 calories per day below your TDEE typically yields about 0.5–1 lb of fat loss per week. Aggressive deficits (over 1,000 cal) risk muscle loss, fatigue, and nutrient gaps. Consult a healthcare provider before starting a restrictive diet.
Activity multipliers range from 1.2 to 1.9, so an extremely active person burns roughly 60% more than a sedentary person with the same body stats. Even one step up in activity adds 200–400 calories per day for most people.
No. Mifflin-St Jeor uses total body weight, not lean mass. Very muscular individuals may have a higher actual BMR than the estimate, while people with above-average body fat may have a lower one.
Estimate only. Results reflect your inputs and standard formulas — they are not financial, tax, legal, health, or investment advice. Verify important decisions with a qualified professional.