Health, Fitness & Body Calculators

Health & Fitness Calculators

Estimate body metrics, calorie targets, nutrition macros, workout numbers, heart rate zones, sleep times, and selected health screening values.

Most calculators support US and metric inputs and show formulas, examples, assumptions, and related tools.

These calculators are educational estimates only and are not medical, nutrition, fitness, legal, or emergency advice.

Body Size & Composition

Choose a calculator, enter realistic inputs, and review the estimate with its assumptions.

BMI Calculator

Estimate adult body mass index from height and weight.

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Ideal Weight Calculator

Estimate ideal body weight using Devine and comparison formulas.

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Healthy Weight Calculator

Estimate the adult weight range associated with BMI 18.5 to 24.9.

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Body Fat Calculator

Estimate body fat percentage from circumference measurements.

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Army Body Fat Calculator

Estimate body fat using an Army-style circumference method.

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Lean Body Mass Calculator

Estimate lean body mass from weight and body fat percentage.

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Calories & Nutrition

Choose a calculator, enter realistic inputs, and review the estimate with its assumptions.

BMR Calculator

Estimate basal metabolic rate with the Mifflin-St Jeor equation.

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Calorie Calculator

Estimate daily calories for weight loss, maintenance, or gain.

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TDEE Calculator

Estimate total daily energy expenditure from BMR and activity.

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Macro Calculator

Estimate daily protein, carbohydrate, and fat targets from calories.

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Protein Intake Calculator

Estimate daily protein target from body weight and training goal.

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Carbohydrate Calculator

Estimate daily carbohydrate grams from calories and macro percentage.

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Fat Intake Calculator

Estimate daily fat grams from calories and macro percentage.

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Fitness & Training

Choose a calculator, enter realistic inputs, and review the estimate with its assumptions.

Calories Burned Calculator

Estimate calories burned from activity duration, body weight, and intensity.

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Target Heart Rate Calculator

Estimate target heart rate range using maximum heart rate.

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Heart Rate Zone Calculator

Estimate common training zones from age and resting heart rate.

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Running Pace Calculator

Calculate running pace, speed, and estimated finish time.

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One Rep Max Calculator

Estimate one-rep max from lifted weight and repetitions.

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Health Metrics

Choose a calculator, enter realistic inputs, and review the estimate with its assumptions.

Body Surface Area Calculator

Estimate body surface area using the Mosteller formula.

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GFR Calculator

Estimate adult eGFR using the 2021 race-free CKD-EPI creatinine equation.

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BAC Calculator

Estimate blood alcohol concentration using a Widmark-style equation.

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Lifestyle & Recovery

Choose a calculator, enter realistic inputs, and review the estimate with its assumptions.

Water Intake Calculator

Estimate daily water intake from body weight, activity, and climate.

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Sleep Calculator

Estimate bedtime or wake time using 90-minute sleep cycles.

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FAQ

Health & Fitness Calculator Questions

What can I estimate with health and fitness calculators?

You can estimate BMI, BMR, daily calories, TDEE, weight ranges, body fat, macros, protein, carbs, fat, water intake, calories burned, heart rate zones, running pace, one-rep max, body surface area, eGFR, BAC, and sleep timing.

Are these calculators medical advice?

No. They are general educational calculators only. They do not diagnose, treat, or replace professional medical, nutrition, fitness, legal, or emergency advice.

Can I use US and metric units?

Yes. Most body, nutrition, and fitness calculators include a unit selector so you can enter common US or metric measurements.

Why can actual results differ?

Real results can differ because of body composition, measurement accuracy, age, sex, pregnancy, medications, medical conditions, training status, alcohol metabolism, sleep quality, and lab methods.

Which calculators should I start with?

For nutrition planning, start with BMR, TDEE, Calorie, Macro, and Protein Intake. For body metrics, start with BMI, Healthy Weight, Body Fat, and Lean Body Mass.