How Big Should My Calorie Deficit Be?
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There is no single deficit that fits every body. Use the Calorie Deficit Calculator to estimate maintenance, then evaluate the proposed deficit as a percentage and an implied weekly rate.
Absolute versus percentage deficit
A 500-kcal deficit is 25% of a 2,000-kcal maintenance estimate but only about 17% of 3,000 kcal. Percent context makes the same subtraction easier to compare.
| Starting concept | Calculation | Interpretation |
|---|---|---|
| 10% below maintenance | TDEE × 0.90 | Modest starting estimate |
| 15% below maintenance | TDEE × 0.85 | Moderate relative change |
| 20% below maintenance | TDEE × 0.80 | Larger change requiring more scrutiny |
These are planning examples, not medical prescriptions. The suitable range depends on body size, current intake, training, health, medications, and nutritional adequacy.
Check the implied rate
CDC describes about 1 to 2 lb per week as gradual, steady loss for many adults, but smaller bodies and people near a healthy weight may appropriately lose more slowly. A calculator should warn when a target date requires an aggressive rate, not celebrate it.
Signs the plan needs review
Persistent dizziness, fainting, marked fatigue, loss of menstrual function, rapid performance decline, recurrent injury, obsessive restriction, or bingeing warrants professional review. Do not solve these problems by merely recalculating.
People who need individualized guidance
Minors, pregnant or breastfeeding people, those with an eating disorder or underweight, older adults with frailty, and people managing major medical conditions or glucose-lowering medication should not use a generic deficit target without an appropriate clinician.
Sources
Evidence and editorial status
Evidence for this package was checked on September 10, 2026. CalculatorGeek should display a named reviewer or professional credential only after that person has completed and documented the review. This material is educational and is not medical diagnosis, treatment, or individualized nutrition advice.
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