Why this exists
Most bulking calculators hand you a 500-calorie surplus regardless of whether you have been lifting for six weeks or six years, then stop. They do not tell you how much of the resulting weight will be muscle, how fast you can realistically gain, or when to stop.
Those three things are the entire decision. A surplus without a rate cap and a stopping point is just a licence to gain fat.
Who writes it
A small independent team that builds calculators. Nobody here is a registered dietitian or a strength coach, so there is no expert byline at the top of the page pretending otherwise.
What you get instead is the reasoning laid out. The methodology table lists each band and equation against its source, and where the number is a coaching convention rather than a research finding we label it that way, which happens more often in bulking than most sites admit.
What we are honest about not knowing
- The required surplus is genuinely unknown. The review that examined this concluded exactly that. Beginners build muscle at maintenance. We err small on purpose.
- No validated equation predicts muscle-to-fat ratio. The percentages we show are ranges read off real studies, presented as illustrative rather than calculated.
- The body fat ceiling is contested. We give one anyway, but for a practical reason (the fat has to come off again) rather than the usual partitioning claim, which is unresolved.
- The rate-of-gain model is a coaching heuristic. Widely used, never peer-reviewed. So is the convention that women gain at half the male rate, which the research does not really support in percentage terms.
- Maintenance calories are an estimate. Activity multipliers are convention, not measured cut-offs. Expect to be a few hundred calories out and correct from three weeks of scale data.
No ads, no affiliates, no supplements
There is nothing to sell you here. No adverts, no affiliate links, no protein powder recommendations, no app, no email list. If the calculator tells you to cut before you bulk, nobody here loses money on it.
Privacy
The maths runs on your device. There is no back end here at all ( just files on a CDN) so the numbers you enter have nowhere to go even in principle. Nothing is kept between visits, and we set no advertising or tracking cookies.
Corrections
If you think a number, band or citation here is wrong, tell us and we will either fix it or explain why we disagree: hello@bulkingcalculator.com.
Not medical advice
Obvious, but worth writing down: a form cannot examine you. It has no idea about your bloodwork, your shoulder, or the medication in your bathroom cabinet. Under 18, pregnant or breastfeeding, managing a condition, or taking anything that changes appetite or bodyweight, that plan should come from a person, not this page.