Why this exists
Most cutting calculators subtract a fixed percentage from your maintenance calories and call it a day. That ignores the thing that decides whether a cut preserves muscle: how much energy your fat stores can actually release per day, which scales with how much fat you have.
Ignoring it is why so many lean people wreck a cut. They run the same 500-calorie deficit that worked at 22% body fat, find it stops working at 12%, assume the problem is discipline, and push harder. The deficit was already larger than their fat stores could fund.
Who writes it
A small independent team that builds calculators. None of us holds a clinical qualification, and you will not find a stock photo of a white-coated "Dr. Somebody" vouching for the page, that device is everywhere in this niche and it means nothing.
The substitute is transparency. Every constant and threshold appears in the methodology table with the paper it came from, and anywhere we have extrapolated past what the research actually says, it is marked. Check the sources and you do not have to take our word for any of it.
Where we are honest about uncertainty
- The fat-store ceiling comes from a theoretical paper. Its author reportedly conceded a miscalculation and proposed a lower figure but died before publishing it, so the corrected number has no citable source. We use the conservative version and treat it as a guardrail, not a law. We also flag that the version circulating widely online is off by a factor of 2.2 through a unit error.
- The protein curve is an interpolation. The 2.3 to 3.1 g/kg-of-lean-mass range is published, and so is the instruction that leaner people in bigger deficits should sit higher in it. The exact curve between those points is ours.
- The risk score is a weighted judgement. Each factor traces to real evidence; how much weight each one gets is our call, and the breakdown is shown so you can disagree.
- The 500-kcal break-even figure has caveats. The meta-analysis behind it could not account for protein intake, and most subjects were older and untrained. The real threshold is probably higher for a well-fed lifter.
- Projections are optimistic and we say so. Expenditure falls as you lose weight by more than the weight loss explains, and no reliable correction coefficient is published, so we show a band rather than inventing one.
Nothing to sell you
No adverts, no affiliate links, no fat burners, no coaching, no app, no email list. If the calculator tells you your deficit is too big, nobody here loses anything by it.
Privacy
Your inputs stay on your machine. This is a set of static files with no server behind it, so no request ever carries your weight or body fat anywhere, reload the page and it is all gone. No cookies for advertising or tracking either.
Corrections
If you think a number, threshold or citation here is wrong, tell us and we will fix it or explain why we disagree: hello@cuttingcalculator.com.
Not medical advice
Restricting food is the one thing on this site with real downside if it is the wrong call for you, and a web page has no way of knowing. Anyone under 18, pregnant or breastfeeding, on a GLP-1 or similar, managing a medical condition, or who has ever had a difficult relationship with eating should be getting these numbers from a clinician.