Sports science · Health · Nutrition
Sports science and health calculators
Every calculator shows the formula it uses, where that formula comes from, and when it stops being accurate. Everything runs in your browser: no sign-up, and nothing you enter is stored.
53 calculators
Health & Vitality
All of these- Alcohol Calorie Calculator — What a Night Out Actually CostsSee the damage. Convert your night out into "Slices of Pizza" or "Miles to Run".
- Alcohol Metabolism CalculatorPredict how long until you are sober. "Zero to Hero" timeline based on drinks consumed.
- BMR Calculator — Three Equations and the Spread Between ThemCalculate basal metabolic rate with Mifflin-St Jeor, Harris-Benedict and Katch-McArdle at once, and see how far apart they land on your numbers.
- Caffeine Half-Life CalculatorFind out when your coffee leaves your system so you can sleep.
- Caffeine Metabolism TrackerScientific analysis of how your body clears caffeine based on genetics, smoking, and medication.
- Chronic Disease Nutrition GuideScientific dietary adjustments for common conditions like Diabetes, Hypertension, and CKD.
- Electrolyte Loss Calculator — Sodium, Potassium and Magnesium in SweatEstimate how much Sodium, Potassium, and Magnesium you lose during intense sweating.
- Heat Index Calculator — Plus Wind Chill and UV Risk for Outdoor TrainingCalculate Heat Index, Wind Chill, and UV safety for your next adventure.
- Iron Needs CalculatorEspecially important for female athletes. Calculate your daily iron requirement to prevent anemia.
- Magnesium Calculator — Daily Requirement for Sleep and RecoveryCheck your Magnesium intake and find your daily requirement to reduce anxiety and improve sleep.
- Melatonin Timing CalculatorCalculate the optimal time to take Melatonin for jet lag or sleep onset.
- Menopause Nutrition Calculator — Perimenopause, Menopause & Post-MenopauseCalculate calorie and macro targets adjusted for your menopause stage. Three-stage formula for perimenopause, menopause, and post-menopause with bone health micronutrients.
- Pediatric Growth & DosageComprehensive tracker for child caloric needs, high-protein growth targets, and safe medication dosages.
- Pet Nutritional OptimizerCalculate daily calories and water intake for cats and dogs based on age and activity.
- Pregnancy Nutrient NeedsCalculate your trimester-specific nutrient requirements (Folate, Iron, Calcium) for a healthy baby.
- Sleep Cycle Calculator — Best Bedtime and Wake Time by 90-Minute CyclesFind your optimal bedtime or wake-up time based on 90-minute REM sleep cycles.
- Sleep Performance Calculator for AthletesCalculate your optimal sleep duration by sport, training load, and competition schedule. Evidence-based recommendations from NCAA and military performance research.
- Steps to Calories Calculator — By Body Size, Not a Flat ConstantConvert steps to calories using your stride length and body mass, and see how far the usual flat 0.04 kcal-per-step constant misses for your size.
- Sweat Rate Calculator — Measure Your Own Fluid LossWork out your sweat rate in litres per hour from a weigh-in, weigh-out field test, and get a drinking range that stays safely under your loss.
- TDEE Calculator — Back-Calculated From Your Own Intake and WeightFind your real TDEE from actual intake and weight data. No estimation formulas — back-calculated from your own body's response.
- Vitamin D CalculatorEstimate your sun exposure needs to reach optimal Vitamin D levels based on skin type and latitude.
Metabolism & Nutrition
All of these- Caffeine Pre-Workout CalculatorDetermine your ideal caffeine dosage for peak athletic performance without the jitters.
- Collagen Dosage Calculator — Therapeutic Dose for Joints and SkinFind the effective therapeutic dose of collagen peptides for joint repair and skin health.
- Creatine Loading CalculatorCalculate your optimal creatine loading phase dosage. Maximize muscle saturation in 5-7 days.
- Energy Gel CalculatorCalculate how many energy gels you need for race day. Enter your duration and effort level to get a carb target, gel count, and timed fuelling schedule.
- Intermittent Fasting Calculator — 16:8, 18:6 and 20:4 WindowsPlan your eating and fasting windows (16:8, 18:6, 20:4) for optimal autophagy and fat loss.
- Keto Macro CalculatorGet your precise ketogenic macronutrient split: 75% Fat, 20% Protein, 5% Carbs.
- Macro Calculator — Daily Protein, Carbs and Fat With a Meal PlanGenerate a personalised daily meal plan based on your macros. Set 1200–4500 kcal, choose high-protein, keto, vegan, paleo, or balanced, and get an instant macro breakdown.
- Paleo Macro Calculator — Protein, Fat and Carb SplitCalculate your macro split for the "Caveman Diet" - high protein, moderate fat, low processed carbs.
- Protein Calculator — Daily Intake for Muscle GainCalculate the exact protein needed to maximize muscle hypertrophy based on your weight.
- Zone Diet Blocks CalculatorCalculate your daily "Zone Blocks" for hormonal balance (40% Carbs, 30% Protein, 30% Fat).
Athletic Performance
All of these- Heart Rate Zone CalculatorCalculate your 5 training zones based on Max Heart Rate or Heart Rate Reserve (Karvonen).
- Marathon Race PredictorPredict your marathon time based on a recent race result (5K, 10K, Half) using the Riegel formula.
- Max Heart Rate Calculator — And Why the Formula Is a GuessEstimate maximum heart rate with the 220−age and Tanaka formulas, see the ±10–12 bpm error each carries, and how to test it instead.
- Recovery Time Calculator — Hours Needed by Training Load and SleepEstimate how many hours of recovery you need based on training intensity and sleep quality.
- Running Pace CalculatorCalculate your finish times for popular race distances (5K, 10K, Marathon) based on your pace.
- Target Heart Rate Calculator — Karvonen, %Max, MAF and PolarisedFind your target heart rate for any training intensity using heart rate reserve (Karvonen), percentage of max, the MAF 180 method, or polarised zones.
- VO₂ Max CalculatorEstimate your VO₂ max from a field test (1.5-mile run, Cooper test, or submaximal step test) and see where you rank for your age and sex.
Strength & Muscle
All of these- Body Fat Percentage CalculatorCalculate your body fat percentage using the US Navy method (circumference measurements) or BMI-based estimation. Includes athletic body fat benchmarks.
- DOTS Calculator — Powerlifting Score by BodyweightCalculate your DOTS score from your squat, bench and deadlift total. Shows IPF GL and Wilks alongside it, because the three scales are not interchangeable.
- FFMI Calculator — Fat-Free Mass Index and the Kouri 25 AnchorCalculate FFMI and normalised FFMI from height, weight and body fat. Shows where you sit against the one figure that has a study behind it.
- IPF GL Points Calculator — Official IPF ScoringCalculate IPF GL (Goodlift) points, the formula the IPF scores its own meets with. Separate curves for classic and equipped, powerlifting and bench-only.
- Natural Muscle Potential Calculator — Casey Butt FormulaEstimate your maximum drug-free muscle building potential using the Casey Butt formula. Enter height, wrist, and ankle measurements.
- One Rep Max (1RM) CalculatorCalculate your one-rep max for squat, bench press, deadlift, and overhead press from any rep count using 5 validated formulas.
- Wilks Score CalculatorCalculate your Wilks score and Dots coefficient to compare your powerlifting total across different body weights and between male and female lifters.
Cycling Science
All of these- Cycling Calorie CalculatorCalculate calories burned cycling based on duration, power output, and body weight. Includes on-bike fuelling recommendations.
- Cycling FTP CalculatorCalculate your Functional Threshold Power (FTP) from a 20-minute test and get your 7-zone power training ranges.
- Cycling Gear Ratio CalculatorCalculate your gear development, speed at any cadence, and compare chainring/cassette combinations to find the optimal gearing for any terrain.
- Watts Per Kg Calculator — Power-to-Weight With Real PercentilesCalculate W/kg at 5 seconds, 1 minute, 5 minutes and FTP, and see your percentile against real power-meter data rather than a disputed tier chart.
- What Is VAM in Cycling? VAM Calculator & BenchmarksVAM (Velocità Ascensionale Media) measures your vertical ascent rate in m/hour. Calculate your VAM for any climb and benchmark against recreational and WorldTour pro levels.
Wealth Optimization
All of these- Compound Interest CalculatorCalculate how your investments grow over time using the power of compound interest. Plan your retirement with scientific precision.
- Mortgage CalculatorCalculate monthly repayments, total interest paid, and amortisation schedule for any mortgage. Compare repayment vs interest-only strategies.
- Retirement Income Calculator: FIRE Number & Pension GapCalculate how much retirement income your portfolio can sustain. Includes pension gap analysis, safe withdrawal rate, and inflation-adjusted projections for UK savers.
How we work
How these numbers are produced
An estimating formula is not a fact; it is an approximation that held for some population. So every page prints the formula it used, where that formula came from, and what pushes it off. You do not have to trust us, you can check it.
- The formula is on the page
- Each calculator prints the equation and the values put into it, so you can check the arithmetic yourself instead of taking our word for it.
- The limits are stated
- Estimating formulas have a range they work in. Each page says what pushes a result off, from a week of weight readings moving with water to a population unlike the one the formula came from.
- Your figures stay on your device
- The calculation happens in your browser. There are no accounts, and the weights, doses and health figures you type are never sent to us.