TDEE & protein calculator
Start with a science-based estimate, then calibrate it against your own data — what you ate and how your weight actually moved. That's the only way to find your real numbers. No account, no email, just the math.
Your estimate
Maintenance TDEE
2,407kcal/day
Daily target — lose fat
2,005kcal/day
Protein floor
147g
Protein ceiling
180g
At this target you'd trend about 0.81 lb/week down — assuming the estimate is right. Track for two weeks and calibrate to be sure.
Starting point from Mifflin–St Jeor + a conservative activity factor. Your true burn is personal — the Calibrate tab finds it.
Hit the protein number
147–180 g of protein a day is a lot of food. A clean whey scoop closes the gap without another chicken breast.
Shop protein & aminos →The science behind the numbers
We don't hide the math behind a brand. Here's where each constant comes from and how confident the research is.
For resting metabolic rate we use Mifflin–St Jeor: 10·kg + 6.25·cm − 5·age, then +5 for men or −161 for women. The 1990 validation reported R²=0.71, and it remains the most reliable common prediction equation for healthy adults — outperforming the older Harris–Benedict. Accuracy drops at very high BMI or in very muscular people, which is exactly why the Calibrate tab exists.
Mifflin et al. 1990, Am J Clin Nutr (PubMed 2305711) ↗The textbook 1.2–1.9 activity factors trace to early-20th-century cohorts and tend to overshoot the needs of modern, mostly-seated people by roughly 15–25%. We deliberately use lower multipliers as a starting point. This isn't the tool being stingy — it's the tool being honest about the data.
TDEE activity-multiplier research review, 2026 ↗Constrained-energy-expenditure research (Pontzer and colleagues) shows the body adapts at higher activity, so TDEE does not keep climbing in a straight line as you train more. That's a second reason very high 'very active' multipliers mislead — and why calibrating against your own weight trend beats any formula.
Constrained total energy expenditure model (PMC review) ↗Energy balance says: change in body stores = intake − expenditure. So if you know your average intake and how your weight actually trended, you can solve for your real expenditure: TDEE ≈ average intake minus the daily energy implied by the weight change. Lose weight faster than expected and your true burn is higher than any calculator guessed. This is the same identity MacroFactor-style adaptive engines run.
Energy balance principle · adaptive-expenditure engines ↗Converting a weight trend into an energy gap uses the classic figure of about 7,700 kcal per kg (≈3,500 kcal per lb) for the fat-mass component. It's an approximation — early-diet water shifts and lean-mass changes muddy it — which is why we recommend a window of at least two weeks and a smoothed (7-day average) weight at each end.
Wishnofsky energy-density approximation ↗Morton et al. 2018 pooled 49 randomized trials (n≈1,863) and found the gains in fat-free mass flatten beyond a breakpoint of ~1.62 g/kg/day, with the confidence interval reaching ~2.2 g/kg. We set the floor at 1.6 (higher, 1.8, when you're cutting, since protein needs rise in a deficit) and the ceiling at 2.2. Above that, the meta-analytic evidence shows no further gain.
Morton et al. 2018, Br J Sports Med (PubMed 28698222) ↗This tool is for general education, not medical or dietetic advice. It models calorie and protein targets from the numbers you enter and makes no claims about diagnosing, treating, or preventing any condition. If you are pregnant, have a medical condition, or have a history of disordered eating, talk to a clinician or registered dietitian before changing your intake.
