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The Catalyst Project
Health, fitness, nutrition, and body composition calculators. Evidence-based formulas — TDEE, BMI, macros, body fat, sleep debt, caffeine timing, and more.
29 free tools — no account required.
Free one-rep-max calculator with the formulas explained: Epley 1RM = weight × (1 + reps/30), Brzycki 1RM = weight / (1.0278 − 0.0278 × reps), Lombardi 1RM = weight × reps^0.10. Compares all three.
Open calculatorFree BAC calculator with the Widmark formula explained: BAC% = (A × 5.14 / (W × r)) − (0.015 × t). Standard-drink conversions, metabolism rate, sleep impact.
Open calculatorUnderstand your blood pressure readings with context on categories, risk factors, and lifestyle recommendations.
Open calculatorFree BMI calculator with the formula explained: metric BMI = weight(kg) / height(m)², imperial BMI = (weight(lb) × 703) / height(in)². Includes waist-to-height ratio for better metabolic risk assessment.
Open calculatorFree Mifflin-St Jeor BMR calculator with the equation explained: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 (men) or −161 (women). Also runs Harris-Benedict and Katch-McArdle.
Open calculatorCalculate your biological age based on fitness, lifestyle, and health markers. Compare your body age to your chronological age.
Open calculatorFree US Navy body fat calculator with the formula explained: men %BF = 86.010×log10(waist−neck) − 70.041×log10(height) + 36.76; women %BF = 163.205×log10(waist+hip−neck) − 97.684×log10(height) − 78.387.
Open calculatorFree caffeine calculator with the half-life formula explained: C(t) = C_initial × (0.5)^(t/half_life). 5-6 hour half-life in most adults. Plus dose timing for sleep and safe daily ceilings.
Open calculatorFree calories-burned calculator with the formula explained: calories = MET × weight_kg × duration_hours. MET values from the Compendium of Physical Activities. More accurate than wearable estimates.
Open calculatorCalculate your optimal creatine loading and maintenance doses based on body weight and goals.
Open calculatorAssess your flexibility across major muscle groups and get targeted stretching recommendations.
Open calculatorCalculate your 5 training heart rate zones using the Tanaka formula and Karvonen method. Optimize cardio for fat burn or performance.
Open calculatorFree heart-rate-zone calculator with the formulas explained: Tanaka HRmax = 208 − 0.7 × age; Karvonen target HR = ((HRmax − HRrest) × intensity%) + HRrest. Five training zones from Z1 recovery to Z5 VO2max.
Open calculatorFree ideal body weight calculator running all four classic formulas. Devine: 50 + 2.3 × (in − 60) for men. Robinson, Miller, Hamwi variations compared.
Open calculatorFree intermittent fasting calculator comparing 12:12, 14:10, 16:8, 18:6, 20:4, OMAD, 5:2, and ADF protocols. Autophagy and ketosis thresholds, beginner ramp-up plan.
Open calculatorFree macro calculator with the formula explained: protein 0.7–1.0 g/lb bodyweight (4 kcal/g), fat 0.3–0.45 g/lb (9 kcal/g), carbs fill remaining calories. Cutting / maintenance / bulking phase ratios included.
Open calculatorPlan your weekly meal prep based on your macros, budget, and time constraints. Get batch cooking recommendations.
Open calculatorPlan your fasting protocol with optimized meal timing and evidence-based benefits. Supports 14:10, 16:8, 18:6, and 20:4.
Open calculatorCalculate your daily vitamin and mineral requirements based on age, sex, and activity level.
Open calculatorFree running pace calculator with the formulas explained: pace = time/distance, speed (mph) = 60/pace, Riegel race prediction T2 = T1 × (D2/D1)^1.06. Predict marathon time from a 5K.
Open calculatorFree protein calculator with the formula explained: protein_g/day = bodyweight_lb × target_g/lb. Targets: 0.36 RDA, 0.73 active (Morton 2018 meta-analysis), 1.0 cutting, 1.2 recomp.
Open calculatorPlan simultaneous fat loss and muscle gain with evidence-based calorie and protein targets.
Open calculatorEstimate your recovery needs based on training intensity, sleep, stress, and nutrition. Optimize rest days.
Open calculatorCalculate your accumulated sleep deficit and get a recovery plan. Understand how sleep debt impacts performance.
Open calculatorFree TDEE calculator with the formula explained: TDEE = BMR × activity factor, where BMR uses Mifflin-St Jeor (10W + 6.25H − 5A + 5 for men, − 161 for women) and activity ranges from 1.2 (sedentary) to 1.9 (very active).
Open calculatorFree training volume calculator using Schoenfeld meta-analyses: 10-20 working sets per muscle per week for hypertrophy, split across 2+ sessions. MEV, MV, MRV thresholds explained.
Open calculatorFree VO2max estimator with the formulas explained: Cooper 12-min run VO2max = 35.97 × miles − 11.29; Rockport 1-mile walk = 132.853 − 0.0769×weight − 0.3877×age + 6.315×sex − 3.2649×time − 0.1565×HR.
Open calculatorFree water intake calculator with the formula explained: water_oz/day = bodyweight_lb × 0.5 + exercise + climate + altitude adjustments. The 8×8 rule under-recommends for anyone above 130 lb.
Open calculatorFree weight-loss calculator with the formula explained: deficit_kcal = TDEE − intake, weekly_loss_lb = deficit × 7 / 3500. Realistic timeline with adaptive thermogenesis caveats.
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