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26 Free Tools · Instant Results

Free Online Health & Fitness Calculators

Your health deserves precision. Our health and fitness calculators use medically validated formulas to help you understand your body, plan your nutrition, and achieve your fitness goals.

Open Fitness Suite →All Categories

26+

Tools

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BMI Calculator

BMI with WHO risk classification, ideal weight & body fat estimate

PopularCharts

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Calorie Calculator

TDEE with 5 goals, 2 formulas, macros & weekly weight projection

PopularCharts

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Period & Cycle Calculator

Adaptive cycle prediction with ovulation window, fertile days, phase visualization, irregular cycle detection & health insights

Popular

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Ovulation Calculator

Predict your ovulation date and fertile window based on your cycle length

Popular

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Sleep Calculator

Calculate ideal bedtimes and wake times based on 90-min REM sleep cycles

Popular

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Calories Burned

Calories burned by 30+ exercises using MET values and body weight

PopularCharts

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Recently Added

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Water IntakeNew

Daily water needs by weight, activity & climate

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Period & Cycle CalculatorNew

Adaptive cycle prediction with ovulation window, fertile days, phase visualization, irregular cycle detection & health insights

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Ovulation CalculatorNew

Predict your ovulation date and fertile window based on your cycle length

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Fertile Window CalculatorNew

Calculate your exact fertile days for natural conception planning

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Implantation CalculatorNew

Estimate your implantation window — when a fertilized egg attaches to the uterus

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Sleep CalculatorNew

Calculate ideal bedtimes and wake times based on 90-min REM sleep cycles

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Calories BurnedNew

Calories burned by 30+ exercises using MET values and body weight

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Body Type CalculatorNew

Determine your somatotype (ectomorph, mesomorph, endomorph) with training advice

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GFR CalculatorNew

Glomerular filtration rate (kidney function) using CKD-EPI formula

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BSA CalculatorNew

Body Surface Area using Mosteller, DuBois and Haycock formulas with drug dosage reference

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BAC CalculatorNew

Blood Alcohol Content by drink type with legal limits, time-to-sober chart and safety tips

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Lean Body MassNew

Lean muscle mass using Boer, James and Hume formulas with fat vs lean body composition chart

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Protein CalculatorNew

Daily protein needs by body weight, activity level and goal with food source breakdown

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Healthy Weight CalculatorNew

Healthy weight range using BMI, Hamwi, Devine and Miller formulas with BMI zone chart

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Fat Intake CalculatorNew

Daily fat targets with saturated/unsaturated breakdown and full macro distribution chart

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Army Body Fat CalculatorNew

US Army body fat using circumference measurements with pass/fail against age-based regulation limits

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Conception CalculatorNew

Estimated conception date from due date or LMP with implantation window and pregnancy milestones

All Health & Fitness Tools

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BMR Calculator

Mifflin vs Harris-Benedict with TDEE at all 5 activity levels

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Body Fat Calculator

Body fat % using US Navy method with category classification

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Ideal Weight

4-formula comparison: Devine, Miller, Robinson & Hamwi with BMI range

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Macro Calculator

Protein/carbs/fat targets by goal with donut chart

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Heart Rate Zones

5 training zones using Karvonen formula

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Pregnancy Due Date

Due date via Naegele's Rule with milestone tracker

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One Rep Max

1RM via 3 formulas + full training percentage table

Why Our Health & Fitness Tools?

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Body Composition

BMI, body fat %, and ideal weight using 4 clinical formulas — see where you truly stand.

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Calorie & Nutrition

TDEE, BMR, macros — complete nutrition planning for any goal from weight loss to muscle gain.

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Heart & Training

5 heart rate training zones using the Karvonen formula for optimal cardio and fat burning.

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Women's Health

Period tracking, ovulation prediction, and fertile window — 100% private, runs offline.

Health calculators require medical-grade accuracy. All our formulas are based on peer-reviewed research including Mifflin-St Jeor for BMR, WHO guidelines for BMI classification, and the US Navy method for body fat percentage.