How Many Calories Should I Eat? (2026 Complete Guide)
Quick answer: Your daily calorie needs depend on your age, sex, height, weight, and activity level. The right number is called your TDEE (Total Daily Energy Expenditure). Use our calculator to find yours in 30 seconds — then this guide explains how to use it.
The Mifflin-St Jeor Equation
The Mifflin-St Jeor equation is one of the most widely used formulas for estimating daily calorie needs and is considered more accurate for most people than older methods like the Harris-Benedict equation. It first estimates your BMR (Basal Metabolic Rate — the calories your body burns at rest just to maintain basic functions), then multiplies that number by an activity factor to estimate your TDEE.
Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
| Activity Level | Multiply BMR by |
|---|---|
| Sedentary (desk job) | × 1.2 |
| Lightly Active (1–3 days exercise) | × 1.375 |
| Moderately Active (3–5 days) | × 1.55 |
| Very Active (6–7 days) | × 1.725 |
| Athlete / Physical Job | × 1.9 |
Calorie Targets by Goal
Lose fat: Eat 500 calories below your TDEE per day. This creates the 3,500 weekly calorie deficit needed for approximately 0.45kg of fat loss per week — the safe, sustainable rate that minimises muscle loss.
Build muscle: Eat 200–300 calories above your TDEE. A modest surplus maximises muscle gain while limiting fat gain. Larger surpluses do not build muscle faster but do build more fat.
Maintain weight: Eat at your TDEE. Simple. This is the starting point for everything.
Why Calculators Are Starting Points, Not Rules
TDEE formulas are accurate within about 10% for most people. Individual differences in gut microbiome, NEAT (fidgeting and incidental movement), and metabolic efficiency mean your actual calorie needs may be higher or lower. Use the calculator as your starting point, track your weight over 2–3 weeks, and adjust by 100–200 calories based on what you observe.
Frequently Asked Questions
References
- Mifflin MD et al. A new predictive equation for resting energy expenditure. AJCN, 1990.
- Hall KD et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet, 2011.