Calorie Deficit Calculator
A safe calorie deficit for most adults is 15-20% below maintenance, roughly 300-500 calories a day, which works out to about 0.5-1 lb of weight loss per week. This calorie deficit calculator estimates your daily target from BMR (Mifflin-St Jeor), an activity factor, and your chosen deficit percentage. It is designed for planning, not diagnosis or treatment.
Quick answer
Step 1: estimate BMR from age, sex, weight, and height.
Estimate only. This tool does not provide personal medical advice.
What this tells you
- •Step 1: estimate BMR from age, sex, weight, and height.
- •Step 2: multiply BMR by activity factor to estimate TDEE.
- •Step 3: apply your chosen deficit to estimate target intake.
How to Use
- 1Enter sex, age, weight, and height with current values.
- 2Choose the activity factor that best matches your average week.
- 3Set a deficit percentage and calculate your target calories.
- 4Review BMR, TDEE, and deficit amount together before planning meals.
- 5Recalculate after weight or activity changes to keep targets realistic.
How It Works
Formula
BMR (male) = 10W + 6.25H - 5A + 5
BMR (female) = 10W + 6.25H - 5A - 161
TDEE = BMR x activity factor
Target Calories = TDEE x (1 - deficit%)The calculator first estimates resting energy needs (BMR) using the Mifflin-St Jeor equation, then scales to total daily expenditure (TDEE) with your activity factor, and finally subtracts your chosen deficit.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Moderate activity fat-loss estimate
Useful when creating a weekly nutrition target that is easier to track than day-to-day fluctuations.
Conservative deficit setup
A smaller deficit can be easier to maintain while preserving training performance.
Common mistakes
- Treating formula output as medical diagnosis
- Choosing aggressive deficit without supervision
- Ignoring adherence and recovery signals
Limitations
This is an estimate model. It does not account for medical history, medications, adaptive thermogenesis, menstrual-cycle effects, clinical conditions, or individual response variability.