Calculator · Cut Calculator
Planning a cut: how large should my calorie deficit be?
The Cut Calculator converts an estimated TDEE into three transparent deficit models. It exposes assumptions and limitations instead of claiming one universally optimal deficit.
Result
- Estimated TDEE
- 2,852kcal/day
- Cut calorie model
- 2,282kcal/day
- Static weight-change projection
- 0.52kg/week
- Protein planning value
- 187g/day
Mifflin-St Jeor × activity factor — not a direct expenditure measurement.
20 % below estimated TDEE; arithmetic difference 570 kcal/day.
Arithmetic model using 7,700 kcal/kg only. Real weight change is dynamic and includes water, glycogen and expenditure adaptation.
Internal starting value of 2.2 g/kg bodyweight during a deficit.
The result is a starting model, not a promise of a specific rate of loss. Calibrate it against your actual response and adjust gradually.
Method
How the calculation works
First, resting energy is estimated with Mifflin-St Jeor and expanded into a TDEE model with an activity factor. Then 15, 20 or 25% is subtracted.
A conservative internal product guardrail stops automatic output at 1,500 kcal for the male and 1,200 kcal for the female calculation basis. This software boundary is not a medical definition of safe minimum intake.
The displayed kg/week number divides the arithmetic weekly energy difference by 7,700 kcal/kg. It is a static projection only, not a dynamic bodyweight model.
Methodology: formulas, assumptions and estimate confidence →
Estimate confidence
How reliable is this estimate?
Medium
The percentage arithmetic is clear, but TDEE and bodyweight response are individual estimates. Practical precision is therefore only medium.
Interpretation
How to read your result
The starting number should be calibrated against reality. Multi-week bodyweight trend, training performance, hunger and recovery are more informative than the first calculator output alone.
Where medical, psychological or specialised sport requirements matter, a generic percentage calculator is not the right decision-maker.
Limits
Where this calculator ends
TDEE uncertainty is larger than the uncertainty of a resting-energy equation alone because a broad activity multiplier is added. A blanket ±10% guarantee for total TDEE would be misleading.
The static 7,700 kcal projection does not model adaptive changes in expenditure or short-term weight shifts and should not be read as a precise fat-loss forecast.
Common mistakes
Common mistakes
- 01Reading a static kg/week number as a fat-loss guarantee.
- 02Presenting the 1,500/1,200 kcal guardrail as a medically safe lower limit.
- 03Applying ±10% resting-equation literature to total TDEE.
- 04Choosing a deficit solely by percentage without considering training, body fat and recovery.
Example
A worked example
85 kg, 180 cm, age 28, male, moderate 20% model
Resting-energy estimate: about 1,840 kcal. With activity factor 1.55: about 2,852 kcal TDEE. Twenty percent below: about 2,282 kcal/day. The static projection is only an arithmetic comparison; the real trajectory is then observed.
FAQ
Frequently asked questions
- How fast should I lose weight on a cut?
- There is no universal target for every adult. Body fat, training status, performance goals and deficit size change what is appropriate. Use the output as a starting model and evaluate your response.
- Is a 25% deficit dangerous?
- The percentage alone cannot provide an individualized medical assessment. In this calculator it is simply the strongest of the three models and deserves especially conservative interpretation.
- How much protein does the calculator show?
- 2.2 g/kg bodyweight as a simple internal planning value. It is not individually optimized; the literature supports a context-dependent range rather than one magic number.
- Why doesn't weight loss match the projection exactly?
- Because bodyweight is not a linear fat-only compartment. Water, glycogen, gut content and adaptations in energy expenditure change the trajectory.
- When should I use professional support?
- Medical conditions, pregnancy, a history of eating disorders, underweight or significant psychological distress around food and weight are better handled with individualized professional support than this general calculator.
Sources
Sources
- 01Aragon AA, Schoenfeld BJ, Wildman R, et al. International Society of Sports Nutrition Position Stand: Diets and Body Composition. Journal of the International Society of Sports Nutrition. 2017;14:16.
- 02Hector AJ, Phillips SM. Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance. International Journal of Sport Nutrition and Exercise Metabolism. 2018;28(2):170–177.
- 03Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet. 2011;378(9793):826–837.
- 04Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition. 1990;51(2):241–247.
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Nutrition
Lose Fat and Keep Muscle. What Actually Works
Fat loss follows no secret method. For your body to release stored energy, a calorie deficit has to be maintained over a longer period of time. How well a diet works, however, is not decided only by how fast body weight drops. Sensible fat loss should preserve as much muscle mass, training performance, and everyday capacity as possible. The decisive fundamentals are a controlled calorie deficit, sufficient protein, consistent resistance training, enough everyday movement, and a realistic evaluation of your progress.
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