How this calculator works
We first estimate your Basal Metabolic Rate (BMR), the energy your body uses at complete rest, using the Mifflin-St Jeor equation. In studies comparing common formulas, it was the most accurate for most adults.
Your TDEE is your maintenance level: eat this much and your weight stays roughly stable.
How big should your deficit be?
A deficit of about 500 kcal per day works for most people. It leads to roughly 0.5 kg (1 lb) of loss per week, which is fast enough to stay motivated and slow enough to keep muscle and energy. Bigger deficits work on paper, but hunger, fatigue and muscle loss make them hard to sustain.
Treat it as a starting point
Every formula is an estimate, typically within about 10% for most people. Eat at your target for 2–3 weeks and track your average weekly weight. If it isn't moving, drop 100–150 kcal. If you're losing faster than 1% of body weight per week, add some back.