What is a calorie deficit?

Worked examples from the same calculator

Unless the row says otherwise: age 30, 70 kg, 175 cm, male coefficient. PAL 1.4–1.6 is an illustrative, explicitly chosen scenario. Intake is 2,000–2,200 kcal/day unless specified. Only the final output is rounded using decimal half-up rules.

What is calorie deficit arithmetic?

Daily deficit = estimated total daily expenditure − daily intake. Positive means a deficit, negative means a surplus. Enter the same intake in both fields for a single intake assumption. Intake must cover the same daily period as expenditure.

Calculate a scenario range

Lower deficit = lower expenditure − upper intake. Upper deficit = upper expenditure − lower intake. This combines the entered extremes conservatively; it is not a statistical confidence interval. If the range crosses zero, these assumptions do not resolve whether there is a deficit or surplus.

Why a deficit does not predict a weight-loss date

Hall and colleagues model changing energy expenditure as body weight changes. A fixed 3,500-kcal-per-pound rule ignores these adaptations. This tool calculates energy balance only; it has no linear pounds-per-week or target-date prediction and does not implement the Hall dynamic model.

Source formulas and scope

The simplified equations in the original Mifflin–St Jeor PubMed abstract read:

REE (males) = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) + 5; REE (females) = 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) - 161.

Output is estimated REE in kcal/day. Original study: 498 healthy adults, ages 19–78. This tool excludes children, pregnancy and breastfeeding; it provides no medical advice. The equation’s two coefficients reflect the study, and do not establish validation for other populations. US inputs use exactly 1 lb = 0.45359237 kg and 1 in = 2.54 cm without intermediate rounding. Other maximum input limits only prevent extreme or accidental entries; they are not clinical thresholds.

NIDDK’s PAL guidance states:

Typical physical activity level numbers range from 1.4 (sedentary) to 2.5 (very active).

REE × PAL is this tool’s initial approximation of total daily expenditure. PAL is selected by you, separately from the original resting-energy equation. Ranges reflect the entered scenarios, not personal error bounds. Hall et al. describe the static rule as “This ubiquitous weight-loss rule (also known as the 3500 kcal per pound rule)” and explain that it ignores physiological adaptations. The dynamic Hall model is not implemented here; no weight-change timeline is calculated.

Use the tool that matches your question

BMI describes a weight-to-height ratio; resting energy excludes activity; maintenance considers daily expenditure; deficit compares expenditure with intake; the gain tool adds your chosen surplus; macro conversion counts energy from entered grams.

• How do you calculate BMI?
• RMR calculator: estimate resting energy
• How to calculate maintenance calories
• Weight gain calculator: starting calorie scenarios
• Calories in protein: grams to kcal calculator

For a specific activity session, use the walking calorie calculator or sit-ups calorie calculator. Their session estimates are separate from whole-day expenditure; avoid counting an activity twice.