Which formula should I use?

Mifflin-St Jeor. Validation studies find it the most accurate general-population BMR equation; Harris-Benedict is older and runs slightly high.

How do I pick an activity level?

Count deliberate exercise plus your job. Desk job with 1–3 workouts a week is 'light'; 3–5 workouts is 'moderate'; daily hard training or a physical job is 'active' or 'very active'. Most people overestimate — when in doubt, pick the lower level.

Is TDEE the number of calories I should eat?

It is the estimate of what you burn. Eat around it to maintain, below it to lose weight and above it to gain. Track your weight for two to three weeks and adjust by 100–200 kcal if the trend does not match.

Why is the result different from my fitness tracker?

Trackers estimate activity from movement and heart rate and are often off by 20% or more. Formulas are off too, but in a predictable way; use whichever you then adjust against real weight change.

TDEE Calculator

Calculate your Total Daily Energy Expenditure with the Mifflin-St Jeor or Harris-Benedict formula and get calorie targets for a cut or a lean bulk.

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Formula: BMR (Mifflin-St Jeor) = 10·kg + 6.25·cm − 5·age + 5 (men) / − 161 (women); TDEE = BMR × activity factor

Worked examples

30-year-old man, 178 cm, 80 kg, moderately active
A typical starting point: the Mifflin-St Jeor BMR of about 1,770 kcal becomes roughly 2,740 kcal at a moderate activity level.
28-year-old woman, 165 cm, 62 kg, lightly active
Shows why an aggressive 750 kcal cut can push a smaller person near the level most guidelines treat as the floor.
Same man as example 1, Harris-Benedict formula
The older Harris-Benedict equation runs about 80–120 kcal higher for the same person; Mifflin-St Jeor is the better-validated default.

What TDEE means

Total Daily Energy Expenditure is the number of calories your body uses in a day: the energy needed to keep you alive at rest (your basal metabolic rate, BMR), plus digestion, plus everything you do — walking, working, training. If you eat about your TDEE your weight stays roughly stable; eat less and you lose weight, eat more and you gain.

How the calculator works

It estimates your BMR from sex, age, height and weight using the Mifflin-St Jeor equation (the default) or the older Harris-Benedict equation.
It multiplies BMR by an activity factor between 1.2 (sedentary) and 1.9 (very active) to get TDEE.
It shows three common targets: a moderate cut (500 kcal below TDEE, about 0.45 kg or 1 lb of fat per week), an aggressive cut (750 kcal below) and a lean bulk (300 kcal above).

Why the two formulas differ

Harris-Benedict was published in 1919 and revised in 1984; Mifflin-St Jeor was published in 1990 from a more representative sample and, in comparison studies, predicts measured resting metabolic rate within 10% for more people than any other general equation. For most adults it gives a slightly lower number than Harris-Benedict. Neither accounts for how muscular you are — if you carry unusually high or low lean mass, use a body-fat-based formula such as Katch-McArdle instead.

How to use the result

Treat the number as a starting estimate, not a measurement. Individual metabolic rates vary by around ±10–15% around any formula.
Eat at the target for two to three weeks while weighing yourself under the same conditions each morning. If your average weight moves faster or slower than expected, adjust intake by 100–200 kcal and repeat.
Do not cut below roughly 1,200 kcal (women) or 1,500 kcal (men) without medical supervision; the aggressive target can reach that range for smaller people.

Activity factors used

| Level | Factor | Typical week | |---|---|---| | Sedentary | 1.2 | Desk job, little or no exercise | | Light | 1.375 | Light exercise 1–3 days | | Moderate | 1.55 | Moderate exercise 3–5 days | | Active | 1.725 | Hard exercise 6–7 days | | Very active | 1.9 | Hard daily training plus a physical job |

These multipliers come from the original Harris-Benedict activity scale and are used unchanged with the Mifflin-St Jeor BMR, which is standard practice.

Limits

This is a general-population estimate. Pregnancy, thyroid conditions, medications and very high or very low body fat all move the true value away from the formula. The calculator is informational and not medical advice.

Frequently asked questions

Which formula should I use?: Mifflin-St Jeor. Validation studies find it the most accurate general-population BMR equation; Harris-Benedict is older and runs slightly high.
How do I pick an activity level?: Count deliberate exercise plus your job. Desk job with 1–3 workouts a week is 'light'; 3–5 workouts is 'moderate'; daily hard training or a physical job is 'active' or 'very active'. Most people overestimate — when in doubt, pick the lower level.
Is TDEE the number of calories I should eat?: It is the estimate of what you burn. Eat around it to maintain, below it to lose weight and above it to gain. Track your weight for two to three weeks and adjust by 100–200 kcal if the trend does not match.
Why is the result different from my fitness tracker?: Trackers estimate activity from movement and heart rate and are often off by 20% or more. Formulas are off too, but in a predictable way; use whichever you then adjust against real weight change.

These calculators give general estimates from published formulas. They are not medical advice and do not account for your individual health; talk to a qualified professional before changing your diet or training.