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Health & Fitness

Browse all 33 health & fitness tools

What is health and fitness calculators?

Health and fitness calculators use validated formulas, such as the Mifflin-St Jeor equation for calorie estimation and the US Navy method for body fat, to give you personalized metrics based on your body measurements and goals.

A1C Calculator

Convert A1C to average glucose and back, with the full A1C chart and ADA bands.

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Basal Metabolic Rate (BMR) Calculator

Calculate BMR using 3 validated formulas. See daily calorie needs by activity level.

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Blood Alcohol Calculator (BAC)

Estimate BAC using the Widmark formula. Enter drinks, weight, and hours to gauge impairment.

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Blood Type Calculator

Predict a child's possible blood types from both parents, with probabilities.

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BMI Calculator

Calculate BMI and see your weight category. Includes healthy weight range for your height.

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Body Fat Calculator

Calculate body fat percentage using the US Navy method with simple body measurements.

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Calorie Calculator

Calculate daily calorie needs with BMR and TDEE. Get targets for weight loss, maintenance, or gain.

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Cholesterol Ratio Calculator

Work out total-to-HDL and LDL-to-HDL ratios plus non-HDL cholesterol, with risk bands.

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Creatinine Clearance Calculator

Estimate creatinine clearance using Cockcroft-Gault, with CKD stage ranges.

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Cycling Cadence Calculator

Convert between cadence, gearing and speed for any wheel size.

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Heart Rate Zone Calculator

Find your 5 heart rate training zones using age or resting HR. Supports Karvonen method.

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Ideal Weight Calculator

Calculate your ideal weight using 4 formulas: Devine, Robinson, Miller, and Hamwi.

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Intermittent Fasting Calculator

Calculate fasting and eating windows for 16:8, 18:6, 20:4, and OMAD protocols.

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IV Drip Rate Calculator

Calculate drops per minute and mL/hr from volume, time and drop factor.

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Keto Calculator

Calculate keto macros with net carb, fat, and protein targets based on your TDEE and goals.

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Lean Body Mass Calculator

Calculate lean body mass using 3 scientific formulas from your weight and height.

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Life Expectancy Calculator

Estimate life expectancy based on age, gender, smoking, exercise, and BMI factors.

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Macro Calculator

Calculate daily protein, carb, and fat targets using TDEE and goal-based macro presets.

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Medication Dosage Calculator

Calculate weight-based medication doses and liquid volumes using mg/kg formulas.

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Menstrual Cycle Calculator

Predict next periods, fertile windows, and ovulation dates from your cycle length.

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One Rep Max Calculator

Calculate your 1RM using 3 formulas and see a loading chart for rep ranges.

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Protein Intake Calculator

Find your daily protein target in grams based on weight, activity, and fitness goal.

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Running Pace Calculator

Calculate pace, finish time, or distance for any run. Projects 5K to marathon finish times.

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Sleep Cycle Calculator

Find bedtimes and wake times that land between 90-minute sleep cycles.

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Smoking Cost Calculator

Calculate the financial cost of smoking and see what you could save by quitting.

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Sobriety Calculator

Track days sober, money saved, and recovery milestones on your sobriety journey.

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Steps to Miles Calculator

Convert steps to miles, km, and calories burned using your height and weight.

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Swimming Pace Calculator

Work out pace per 100m or 100y and project race split times.

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Target Heart Rate Calculator

Find target heart rate zones by age, including the Karvonen reserve method.

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TDEE Calculator

Calculate daily calories burned and recommended macros for your activity level and goals.

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VO2 Max Calculator

Estimate VO2 Max from a run test, walk test, or resting heart rate. See fitness category.

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Waist-to-Hip Ratio Calculator

Calculate your waist-to-hip ratio and see WHO health risk classification.

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Water Intake Calculator

Calculate how much water you need daily based on weight, activity, and climate.

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Formula & Methodology

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Did you know? The BMI formula was invented by Belgian mathematician Adolphe Quetelet in the 1830s as a population-level statistical tool, not as a diagnostic measure for individuals, which is why many health professionals now complement it with body fat percentage and waist measurements.

Sources

  • World Health Organization (WHO): BMI classification and healthy weight guidelines
  • National Institutes of Health (NIH): Physical activity, calorie, and hydration recommendations

Frequently Asked Questions

The Mifflin-St Jeor equation is considered the most accurate for most people. It calculates BMR (Basal Metabolic Rate) from height, weight, age, and sex, then multiplies by an activity factor to get TDEE (Total Daily Energy Expenditure).

BMI is a useful screening tool but has limitations: it does not distinguish between muscle and fat. Athletes may have a high BMI but low body fat. Use it alongside body fat percentage and waist circumference for a fuller picture.

Heart rate zones are percentage ranges of your maximum heart rate. Zone 1 (50 to 60%) is recovery, Zone 2 (60 to 70%) is fat burning, Zone 3 (70 to 80%) is aerobic, Zone 4 (80 to 90%) is anaerobic threshold, and Zone 5 (90 to 100%) is maximum effort.

A common guideline is 8 cups (2 liters) daily, but the National Academies recommend 3.7 liters for men and 2.7 liters for women from all sources (food and drink). Use the Water Intake Calculator for a personalized estimate based on weight and activity.

VO2 Max is the maximum rate at which your body can consume oxygen during intense exercise, measured in mL/kg/min. It is one of the best indicators of cardiovascular fitness and longevity. Elite runners may have VO2 Max values above 70; the average adult falls between 30 to 50.