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Health calculators and tools

Health calculators using age, sex, height, weight, activity, and other relevant inputs for screening and planning estimates.

BMI CalculatorCalculate adult BMI from height and weight, then use age and sex for an estimated body-fat percentage and contextual guidance.Calorie CalculatorEstimate daily maintenance calories from age, sex, height, weight, and activity level.TDEE CalculatorFree online TDEE calculator for BMR, maintenance calories, calorie deficit, and weight-loss planning. Use metric or imperial inputs with Mifflin-St Jeor.Maintenance Calorie CalculatorEstimate maintenance calories from age, sex, height, weight, and activity using the Mifflin-St Jeor equation.BMR CalculatorEstimate basal metabolic rate from age, sex, height, and weight with the Mifflin-St Jeor equation.RMR CalculatorEstimate resting metabolic rate from age, sex, height, and weight with the Mifflin-St Jeor equation.Estimated Energy Requirement CalculatorEstimate adult daily energy requirement from age, sex, height, weight, and physical activity using Dietary Reference Intake EER equations.Ideal Weight CalculatorCompare sex-specific adult ideal body-weight estimates from height using the Devine formula.Healthy Weight CalculatorEstimate an adult healthy weight range from height using the BMI 18.5 to 24.9 screening range, with a current BMI comparison.Water Intake CalculatorEstimate daily water intake from body weight and activity adjustment.Macro CalculatorCalculate protein, carbohydrate, and fat gram targets from daily calories, macro percentages, direct protein grams, or grams per kilogram body weight.Carb CalculatorCalculate daily carbohydrate grams and carbs per meal from calorie target, carbohydrate percentage, and meal count.Keto CalculatorPlan keto-style macros by setting daily calories, net carbs, and protein, then assigning remaining calories to fat grams.Thermic Effect of Food CalculatorEstimate the thermic effect of food from protein, carbohydrate, fat, alcohol grams, and low, midpoint, or high TEF ranges.Pregnancy Due Date CalculatorEstimate a pregnancy due date from the first day of the last menstrual period.Body Fat Percentage CalculatorEstimate body fat percentage with the Navy tape method or a quick BMI-based comparison using height, weight, sex, and body measurements.Army Body Fat CalculatorEstimate body fat percentage with an Army-style tape method using height, neck, waist or abdomen, hip when needed, sex, and body weight.Body Surface Area CalculatorEstimate body surface area from height and weight using common adult formulas.Sleep CalculatorFind bedtimes or wake times based on 90-minute sleep cycles.Target Heart Rate Zones CalculatorEstimate moderate and vigorous heart rate training zones from age.Running Pace CalculatorCalculate pace per kilometer, pace per mile, and average speed from distance and time.Ovulation CalculatorEstimate ovulation and fertile window dates from cycle length and last period date.Blood Pressure Category CalculatorClassify a blood pressure reading into common adult screening categories.VO2 Max EstimatorEstimate VO2 max from resting heart rate and maximum heart rate.One-Rep Max CalculatorEstimate one-rep max strength from a lifted weight and repetitions.Waist to Hip Ratio CalculatorCalculate waist-to-hip ratio (WHR) in inches or cm, compare broad men and women WHR chart thresholds, and learn how to measure waist and hip correctly.Lean Body Mass CalculatorEstimate lean body mass from height, weight, and sex using the Boer formula.Protein Intake CalculatorEstimate daily protein target and protein per meal from body weight, grams per kilogram, and meal count.Protein Per Meal CalculatorEstimate protein per meal from body weight, grams per kilogram, and meal count for muscle gain, cutting, or daily meal planning.Calorie Deficit CalculatorEstimate daily calorie deficit, weekly weight-change pace, and target-loss time.BMI Prime CalculatorCalculate BMI prime, BMI, and the body weight corresponding to BMI 25.

Tool paths

Choose the right health path

Start with the calculator closest to the question, then move sideways to related tools without returning to search.

Calories and metabolism

Start with resting energy, then move to maintenance, deficit, macros, and protein targets.

TDEE calculatorFree online BMR, maintenance calories, deficit, and activity-level estimate.RMR calculatorResting metabolic rate with Mifflin-St Jeor.EER calculatorDietary Reference Intake energy estimate.BMR calculatorBasal metabolic rate from height, weight, age, and sex.Maintenance calorie calculatorWeight-stable daily calorie estimate.Macro calculatorSplit calories into protein, carbs, and fat.Protein intake calculatorDaily protein and per-meal targets.

Nutrition targets

Plan macros, keto-style targets, carbohydrate ranges, and meal thermic-effect estimates from the same cluster.

Macro calculatorProtein, carb, and fat gram targets.Carb calculatorDaily carbohydrate grams and per-meal split.Keto calculatorNet carbs, protein, and remaining fat target.Thermic effect of food calculatorEstimate TEF from meal macros.Grams to calories calculatorConvert macro grams into calorie shares.Protein per meal calculatorSplit daily protein across meals.

Body measures and screening

Use measurement tools together when one number is too narrow for the question.

BMI calculatorBMI plus contextual adult guidance.Healthy weight calculatorAdult BMI healthy-weight range by height.Army body fat calculatorTape-method body-fat estimate.Body fat calculatorNavy, BMI, or skinfold-style estimate.Lean body mass calculatorEstimated lean mass from body size.Waist-to-hip ratio calculatorWaist and hip measurement ratio.

Useful starting points

Start with these health tools

TDEE calculatorFree online BMR, TDEE, maintenance, deficit, and activity-level calorie estimate.

Use health estimates as starting points

Health calculators can estimate BMI, BMR, RMR, TDEE, protein targets, body-fat proxies, hydration, sleep timing, heart-rate zones, and other planning numbers. They work best when height, weight, age, sex, activity, and goal inputs are measured consistently rather than guessed.

A formula result is not a diagnosis. Resting-energy and calorie calculators use predictive equations, BMI is a screening measure, and nutrition estimates simplify a person's real diet, training, sleep, health history, and body composition. Use the result to form a starting range, then adjust with real trends and qualified guidance when health choices matter.

When comparing tools, separate resting estimates from activity estimates. RMR and BMR describe energy use at rest; TDEE and maintenance calories add an activity multiplier; macro and protein calculators split or allocate intake targets.