Calorie Calculator
Estimate your daily calorie needs using the Mifflin-St Jeor equation, the formula most dietitians use.
What this calculator does
Estimates your daily calorie needs at rest (BMR) and with activity factored in (TDEE), using the Mifflin-St Jeor equation — widely regarded as one of the more accurate formulas for estimating energy needs across the general population.
Who this is for
Anyone wanting a starting reference point for daily calorie needs, whether for general awareness, weight maintenance, or as one input alongside guidance from a doctor or registered dietitian for any specific goal.
How this calculator works
The Mifflin-St Jeor equation calculates your Basal Metabolic Rate (BMR) — calories burned at rest — then multiplies it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE). A ~500 calorie/day deficit or surplus roughly corresponds to 1 lb of weight change per week.
The formula
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: the same calculation, minus 161 instead of plus 5.
Worked example
A 30-year-old man, 70kg, 175cm, moderately active: BMR = (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 700 + 1,093.75 − 150 + 5 = 1,648.75. TDEE = BMR × 1.55 (moderate activity factor) ≈ 2,556 calories/day to maintain current weight.
Your calorie targets by goal
Run the calculator above to compare your maintenance, deficit, and surplus targets.
Common mistakes
- Cutting too aggressively. A deficit much larger than 500-750 calories/day often leads to muscle loss and metabolic slowdown rather than faster fat loss — moderate, sustainable deficits tend to work better long-term.
- Not adjusting as you lose or gain weight. Your TDEE changes as your weight changes — recalculate periodically rather than using one number indefinitely.
- Underestimating activity level. Most people overestimate how "moderately active" they are — be honest about your actual exercise frequency, since this input meaningfully shifts the result.
- Treating the estimate as exact. Individual metabolic rate varies from the formula's prediction — use the number as a starting point to adjust based on how your weight actually trends over several weeks, not as a precise fixed target.
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Frequently Asked Questions
What's the difference between BMR and TDEE?
BMR is the calories your body burns at complete rest just to maintain basic functions. TDEE adds your activity level on top, giving a more realistic picture of total daily energy needs — TDEE is the more useful number for setting a calorie target.
How accurate is the Mifflin-St Jeor equation?
It's considered one of the more accurate BMR formulas for the general population, but individual metabolism still varies — treat the result as a starting point to adjust based on real-world results over a few weeks.
How much of a deficit should I aim for to lose weight?
A 500 calorie/day deficit roughly corresponds to about 1 lb of weight loss per week, which is generally considered a sustainable pace. Larger deficits can work short-term but are harder to maintain and risk muscle loss.
Should I recalculate as I lose weight?
Yes — your TDEE decreases as you lose weight (a smaller body burns fewer calories at rest and during activity), so recalculating every few weeks keeps the target accurate.