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How many calories should i eat for a deficit?

How many calories should i eat for a deficit: calculation method, required inputs, worked check, limitations and a link to Calorie Calculator. Reviewed 24 Se...

By Uddhav Gopani, FounderPublished 25 September 2026Reviewed 25 September 2026

A deficit is sized from your maintenance number, not chosen from thin air. First estimate maintenance (BMR × activity factor), then subtract: 300–500 kcal per day is the standard moderate band, roughly 10–25% of maintenance, which targets about 0.25–0.5 kg of weekly loss without triggering the adherence and muscle-loss problems of crash deficits.

What this specific question is asking

The floor matters more than the target: do not run a deficit that pushes intake below roughly 1,200 kcal (women) or 1,500 kcal (men) without professional supervision — below those levels, hitting protein and micronutrient needs becomes impractical.

Reality-check the deficit after two weeks: expected loss ≈ weekly deficit ÷ 7,700 kcal per kg. If measured loss is dramatically faster, you are losing water and glycogen, not fat; if slower, your maintenance estimate was high — adjust it, not the deficit rule.

Inputs to verify

Verify weight (kg) before calculation; if this value uses a different unit, period or definition, convert or restate it first.
Verify height (cm) before calculation; if this value uses a different unit, period or definition, convert or restate it first.
Verify age (years) before calculation; if this value uses a different unit, period or definition, convert or restate it first.
Verify sex before calculation; if this value uses a different unit, period or definition, convert or restate it first.
Verify activity level before calculation; if this value uses a different unit, period or definition, convert or restate it first.
Verify goal before calculation; if this value uses a different unit, period or definition, convert or restate it first.

Step-by-step check

Enter your weight, height, and age first.
Pick your sex and activity level.
Choose whether you want to lose, maintain, or gain.
Press Calculate to see your daily calorie target.

Worked example and sanity check

As a worked reference for “How many calories should i eat for a deficit”, Worked example Maintenance calories = BMR × an activity factor. With a BMR of 1,500 kcal and a 'lightly active' factor of 1.375, daily maintenance is ≈ 2,063 kcal . A moderate 500 kcal deficit (~1,563 kcal) is often used as a starting point for gradual change. Individual needs vary widely — treat this as a rough guide and consult a qualified professional for a personalised plan.

Interpreting the result

Once the number is in hand, ask what decision it feeds. The example's BMR × an activity factor shows the expected scale for typical inputs. Use your result the same way: as one checked input into the decision, not the whole decision. Read the magnitude before the decimals: a result ten times too large or small almost always means a unit or period slipped, not that the formula failed.

Reviewed 25 September 2026

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Use the Calorie Calculator

Open Calorie Calculator

Common questions

Which inputs matter most for how many calories should i eat for a deficit?

The key inputs are Weight (kg), Height (cm), Age (years), Sex. Match their units and periods before using Calorie Calculator.

How can I check an answer for how many calories should i eat for a deficit?

Run the example exactly as written, then vary weight (kg) alone. A result that tracks that change predictably tells you the setup — units, periods, definitions — is correct.

When should I recalculate how many calories should i eat for a deficit?

Re-run it when the real-world inputs move — new measurements, changed rates or thresholds, or a different unit convention on the same quantity.