What Is a Calorie Deficit and How Do You Calculate It?

Weight loss, in the simplest terms, is arithmetic: burn more energy than you take in. That gap is the calorie deficit. Here's how to calculate a sensible one without crash-dieting.

Two Numbers You Need

BMR (Basal Metabolic Rate) — the energy your body uses at complete rest to keep you alive. TDEE (Total Daily Energy Expenditure) — your BMR plus everything you burn through activity. Your TDEE is the number your intake must stay below to lose weight.

You can find both with our BMR Calculator and Calorie Calculator.

The Rule of 500

A deficit of about 500 calories per day is the classic sustainable target:

That works out to roughly 0.45 kg lost per week. Faster deficits exist, but they get progressively harder to sustain and can cost you muscle.

Worked Example

A woman with a TDEE of 2,200 calories wants a moderate deficit:

If she also adds a daily 300-calorie walk, her effective deficit grows to 800 calories/day without touching food — showing how activity and intake combine.

Making It Stick

• Prioritize protein and fiber — they keep you full on fewer calories.
• Don't cut too deep. Below ~1,200 (women) / ~1,500 (men) needs professional supervision.
• Re-calculate as you shrink. A lower body weight means a lower TDEE, so your deficit shrinks over time. Recheck monthly.
• Expect fluctuations. Water weight and glycogen mask fat loss on the scale for days at a time.

Track your macros alongside the deficit with our Macro Calculator, and monitor progress with the Body Fat Calculator rather than the scale alone.