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Calculators

Fitness Calculators

Free evidence-based calculators for calories, macros, protein, body composition, creatine, caffeine, hydration, strength and lean mass planning.

Updated 2026-06-10Fast, mobile-friendly toolsResults are estimates, not medical advice
Disclaimer: These calculators provide educational estimates only. They are not medical advice, diagnosis or treatment. Speak with a qualified professional if you have a medical condition, take medication, are pregnant, or have specific clinical needs.
Calories

TDEE / Calorie Calculator

Estimate your daily energy expenditure with the Mifflin-St Jeor equation, then see practical fat loss and lean bulk targets.

Method: BMR uses the Mifflin-St Jeor formula, then multiplies by activity level. For nutrition strategy, see fat loss, muscle growth and the macro calculator.
Estimated result
--
maintenance calories/day
Fat loss target--
Lean bulk target--
Estimated BMR--
Free · printable
Now eat that. The hard part is the protein.

The protein chart: 30+ foods ranked by protein per 100 calories, so you can see what gets you there for the fewest calories.

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Nutrition

Macro Calculator

Turn your calorie target into protein, carbohydrates and fats using practical evidence-based defaults.

Method: Protein is set around 1.6-2.2 g/kg depending on goal, fat around 20-30% of calories, and carbs fill the remaining calories. Pair this with the whey protein hub if protein intake is hard to hit.
Daily macros
--
grams protein
Carbs--
Fats--
Protein target--
Free · printable
Protein is the macro that decides what you keep.

The protein chart: 30+ foods ranked by protein per 100 calories, so you can see what gets you there for the fewest calories.

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Protein

Daily Protein Calculator

Estimate a daily protein range for general fitness, muscle gain or fat loss.

Method: General fitness uses 1.2-1.6 g/kg, muscle gain uses 1.6-2.2 g/kg, and cutting uses 1.8-2.4 g/kg. Useful next: whey protein guide and best whey protein.
Recommended range
--
grams/day
Lower target--
Higher target--
Free · printable
Now hit that number on days you cannot eat much.

The protein chart: 30+ foods ranked by protein per 100 calories, so you can see what gets you there for the fewest calories.

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Body Composition

Body Fat Percentage Calculator

Estimate body fat percentage using the US Navy circumference method.

Method: US Navy equations use height, neck, waist and hips for women. This is a field estimate, not a DEXA scan.
Estimated body fat
--
percent body fat
Estimated lean mass--
Free · printable
Body fat falls fastest when protein holds.

The protein chart: 30+ foods ranked by protein per 100 calories, so you can see what gets you there for the fewest calories.

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Strength

One Rep Max Calculator

Estimate your one-rep max from a submaximal set using the Epley formula.

Formula: 1RM = weight x (1 + reps / 30). Useful next: strength training, training equipment and adjustable dumbbells.
Estimated 1RM
--
kg
90%--
80%--
70%--
Creatine

Creatine Dosage Calculator

Estimate a daily creatine monohydrate dose, optional loading phase and maintenance target.

Method: Standard maintenance is usually 3-5 g/day. Loading can use about 0.3 g/kg/day for 5-7 days, then maintenance around 0.03 g/kg/day or 3-5 g/day. Useful next: creatine benefits guide and best creatine supplements.
Creatine dose
--
grams/day
Maintenance--
Optional loading--
Caffeine

Caffeine Dosage Calculator

Estimate pre-workout caffeine ranges based on body weight and sensitivity.

Method: Low dose is about 1-2 mg/kg, moderate is about 3 mg/kg, and high performance protocols can reach 5-6 mg/kg. Avoid late-day use and do not exceed personal or medical limits. Useful next: caffeine benefits guide and best pre-workout supplements.
Caffeine dose
--
mg before training
Low range--
High cautionAvoid late-day use. Many adults should stay below about 400 mg/day total caffeine.
Hydration

Water Intake Calculator

Estimate daily water needs from body weight, training intensity and climate.

Method: Base intake uses roughly 30-40 ml/kg/day, then adds estimated fluid for training and heat. Useful next: electrolytes and sports hydration if those pages are available in your content plan.
Daily water estimate
--
liters/day
Base range--
Training and heat add-on--
Body Composition

Lean Body Mass Calculator

Calculate lean body mass from body weight and body fat percentage.

Formula: Lean body mass = body weight x (1 - body fat percentage / 100).
Lean body mass
--
kg
Fat mass--
Body Composition

FFMI Calculator

Estimate fat-free mass index and normalized FFMI from height, weight and body fat percentage.

Formula: FFMI = lean mass in kg / height in meters squared. Normalized FFMI adjusts to a reference height of 1.8 m.
Estimated FFMI
--
fat-free mass index
Normalized FFMI--
Lean mass--
Body Composition

Ideal Weight Calculator

Estimate a healthy weight range using the Devine and Hamwi formulas — widely used clinical reference ranges for adults.

Methods: Devine (1974): 50 kg + 2.3 kg/inch over 5 ft (males). Hamwi (1964): 48 kg + 2.7 kg/inch (males). Results are clinical reference ranges, not body composition goals.
Ideal weight range
--
kg
Devine formula--
Hamwi formula--
Healthy BMI range--
Cardio Training

Heart Rate Zone Calculator

Calculate your 5 training heart rate zones from max HR or age. Use these zones to structure Zone 2 cardio, threshold work, and HIIT sessions.

Method: Max HR estimated as 220 − age (Tanaka formula gives similar results). Zone 1: <57% max, Zone 2: 57–63%, Zone 3: 64–76%, Zone 4: 77–95%, Zone 5: 96–100%. Zone 2 is the aerobic base zone, critical for VO₂ max and longevity.
Your max HR
--
beats per minute
Zone 1 (Recovery)--
Zone 2 (Aerobic base)--
Zone 3 (Aerobic power)--
Zone 4 (Threshold)--
Zone 5 (VO₂ max / HIIT)--
Cardio Fitness

VO₂ Max Estimator

Estimate aerobic capacity from resting heart rate using the Uth–Sørensen–Overgaard–Pedersen equation. Higher VO₂ max is the strongest predictor of longevity.

Formula: VO₂ max ≈ 15 × (Max HR / Resting HR). Max HR estimated as 220 − age. Measure resting HR first thing in the morning before getting up for best accuracy.
Estimated VO₂ Max
--
ml/kg/min
Fitness level--
All-cause mortality percentile--
Target (top quartile for age)--
Cardio

Running Calorie Calculator

Estimate calories burned running based on body weight, distance, and pace using MET values from the Compendium of Physical Activities.

Method: Calories = MET × weight (kg) × duration (hours). MET values from Compendium of Physical Activities. Net calories shown (subtract resting metabolic rate for gross).
Estimated calories burned
--
kcal
Duration--
Per km / mile--
MET value used--
Recovery

Sleep Cycle Calculator

Sleep occurs in ~90-minute cycles. Find ideal bedtimes or wake times that align with natural sleep stages so you wake refreshed, not mid-cycle.

Science: Average sleep cycle = 90 minutes (NREM 1–3 + REM). 5 cycles = 7.5 hours — the most common optimal range. Add 15 minutes to account for sleep onset. Waking between cycles is associated with better alertness and lower sleep inertia.
Ideal times
--
Based on 5 sleep cycles (7.5 hours)
Option 1 (4 cycles)--
Option 2 (5 cycles)--
Option 3 (6 cycles)--
More on this
Calorie deficit calculator →Lean body mass calculator →FFMI calculator →