Calorie & Deficit Calculator

Estimate your BMR (resting burn), adjust for activity to get TDEE (maintenance calories), and set an optional deficit or surplus to hit your goals. See steps, a mini bar chart, and a deficit gauge for quick insight.

Background

We use the Mifflin–St Jeor equation for BMR (default). If you provide body fat %, we switch to Katch–McArdle (LBM-based). Your TDEE = BMR × activity factor. Target intake applies a chosen weekly pace to compute an energy delta (≈7700 kcal/kg or 3500 kcal/lb heuristic).

Enter your details

Units & Sex

Use body fat % (Katch–McArdle)

Switching to US units converts values automatically.

Age, height, weight

If you fill body fat %, we'll compute BMR from lean mass; otherwise Mifflin–St Jeor is used.

Activity level

TDEE = BMR × activity factor.

Goal (optional)

Heuristic: ≈ 7700 kcal/kg or 3500 kcal/lb. We flag changes >35% of TDEE.

Show:

Step-by-step working

Mini chart: BMR, TDEE, Target

Deficit/surplus gauge

Round to sensible significant figures

Quick picks:

Chips prefill fields and run the calculation.

Result:

No results yet. Enter inputs and click Calculate.

How this calculator works

BMR (resting): Mifflin–St Jeor uses age, sex, height, weight. If body fat % is provided (and toggled), we switch to Katch–McArdle using lean mass.
TDEE (maintenance): Multiply BMR by your activity factor.
Goal target: Convert weekly pace → daily kcal change (≈3500 kcal/lb or 7700 kcal/kg) and adjust TDEE.
Safety note: We warn if the requested deficit/surplus exceeds ~35% of TDEE.

Formula & Equations Used

Mifflin–St Jeor (kcal/day)

Male: BMR = 10·mass(kg) + 6.25·height(cm) − 5·age + 5

Female: BMR = 10·mass(kg) + 6.25·height(cm) − 5·age − 161

Katch–McArdle (kcal/day)

BMR = 370 + 21.6·LBM(kg), where LBM = mass·(1 − body fat %)

TDEE: BMR × activity factor

Pace → kcal/day: Δ ≈ 7700·pace(kg/wk)/7 or 3500·pace(lb/wk)/7

Example Problem & Step-by-Step Solution

Example 1 — Male, 22 y, 180 cm, 75 kg, moderate, −0.5 kg/week

BMR (MSJ) ≈ 10·75 + 6.25·180 − 5·22 + 5 = 1,764 kcal/day. Activity 1.55 → TDEE ≈ 2,734 kcal/day. Weekly pace −0.5 kg → ≈ 7700·0.5/7 ≈ 550 kcal/day deficit → Target ≈ 2,184 kcal/day.

Example 2 — Female, 21 y, 165 cm, 62 kg, light, maintenance

BMR (MSJ) ≈ 10·62 + 6.25·165 − 5·21 − 161 = 1,379 kcal/day. Activity 1.375 → TDEE ≈ 1,896 kcal/day (target = maintenance).

Example 3 — Male, 28 y, 5'10", 180 lb, moderate, −1 lb/week

Convert: 180 lb ≈ 81.6 kg; 5'10" ≈ 178 cm. BMR (MSJ) ≈ 10·81.6 + 6.25·178 − 5·28 + 5 = 1,820 kcal/day. TDEE ≈ 1,820×1.55 = 2,821 kcal/day. Pace −1 lb/wk → 3500/7 ≈ 500 kcal/day deficit → Target ≈ 2,321 kcal/day.

Example 4 — Female, 30 y, 5'5", 140 lb, sedentary, +0.5 lb/week

Convert: 140 lb ≈ 63.5 kg; 5'5" ≈ 165 cm. BMR (MSJ) ≈ 10·63.5 + 6.25·165 − 5·30 − 161 = 1,378 kcal/day. TDEE ≈ 1,378×1.2 = 1,654 kcal/day. Pace +0.5 lb/wk → 3500·0.5/7 ≈ 250 kcal/day surplus → Target ≈ 1,904 kcal/day.