The fitness numbers,
with the caveats.
Calculators across strength, endurance, body composition, and energy expenditure. Imperial or metric. The formula citations, population limits, and real-world variance most calculators skip.
TDEE & BMR calculator
Three BMR formulas side-by-side (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle). Calorie targets for cutting and bulking. With the activity-multiplier honesty most calculators skip.
Open calculator →Energy expenditure & macros
- TDEE & BMR calculatorthree BMR formulas, calorie targets, activity multiplier honesty
- Macro calculatorprotein/carb/fat targets from TDEE, ISSN-aligned
- Protein calculatorgrams per pound, ISSN ranges by goal
- Calorie deficit calculatorweekly loss math with the long-term adjustment (Hall 2011)
Strength training
- 1RM calculatorEpley, Brzycki, Lombardi, O'Conner, Mayhew side-by-side
- Percentage calculatorworking weights from your 1RM, plate math included
- Plate math calculatorbarbell loading by side, lb and kg plates
- Wilks & IPF GL calculatorpowerlifting bodyweight-adjusted scoring
Body composition
- Body fat calculatorNavy / skinfold / BMI methods compared
- Lean body mass calculatorLBM and fat-free mass index (FFMI)
- BMI calculatorwith the muscular-athlete caveat
- Ideal weight calculatorDevine, Robinson, Miller, Hamwi compared
Endurance & cardio
- Pace calculatorrace pace, splits, distance conversion
- Heart rate zones calculatorTanaka HR_max, Karvonen reserve, 5-zone model
- VDOT calculatorDaniels' running formula, training pace map
- VO2 max calculatorRockport walk test, Cooper run, with Cooper Institute norms
About
Every calculator on performmath shows its math, names its primary citation, and includes a "when this calculator is wrong" section. We treat the fitness audience as capable of reading a study and benefiting from the population caveats most calculators skip. Calorie targets are math estimates, not medical advice — for medical conditions, eating disorders, or significant weight changes, consult a registered dietitian or physician.