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Calculation Machine

Calorie Deficit Calculator

Daily calories to lose a target amount by a chosen date.

Reviewed by the Calculation Machine team · How we check our maths

Your values

ⓘ Live results

Results
Daily calorie target
1,567 kcal
Required daily deficit
833 kcal
Weekly loss rate
1.67 lb/week
Safety check
Sustainable pace

Quick answer

A pound of fat is roughly 3,500 calories, so a 500-calorie daily deficit produces about one pound of loss per week.

The formula

Daily deficit = (lb to lose × 3500) ÷ days

Worked example

Worked example

Using the values the calculator loads with.

Inputs

  • Maintenance calories (TDEE)2400 kcal
  • Pounds to lose20 lb
  • Weeks to do it in12 weeks

Result

  • Daily calorie target1,567 kcal
  • Required daily deficit833 kcal
  • Weekly loss rate1.67 lb/week
  • Safety checkSustainable pace

How to use the Calorie Deficit Calculator

  1. 1Enter your maintenance calories.
  2. 2Set how much you want to lose and by when.
  3. 3Check the pace is sustainable.

Frequently asked questions

Is 3,500 calories per pound exact?

It is an approximation. Metabolic adaptation means real loss slows over time, so recalculate every few weeks.

What is a safe rate?

0.5–1% of body weight per week. Faster loss increases muscle loss and rebound risk.

About this calculator

How a calorie deficit turns into weight loss

Eating fewer calories than you burn makes the body draw on stored energy. A daily deficit of about 500 kcal is the classic target because it works out to roughly 0.5 kg a week, a pace most people can sustain without losing much muscle.

The old rule that 3,500 kcal equals one pound of fat is a reasonable starting estimate, but real-world loss slows over time as your body gets smaller and burns less. Expect the scale to move faster in the first few weeks (partly water) and slower later.

Making the deficit work

  • Aim for a deficit of 10–25% of maintenance, not a fixed large number. Bigger deficits raise hunger and muscle loss.
  • Keep protein high (about 1.6 g per kg of body weight) and keep lifting weights to protect muscle.
  • Judge progress on a two-week average weight, not a single weigh-in.
  • If progress stalls for three weeks, recalculate maintenance at your new weight before cutting further.

Sources

More questions

How big a calorie deficit is safe?

For most healthy adults 300–750 kcal a day is a common range. Very low-calorie diets should be supervised by a doctor.

Why am I not losing weight in a deficit?

Most often intake is underestimated or activity overestimated. Water retention can also hide fat loss for a week or two.