Health & Fitness Calculators
Free, private calculators for your body, nutrition, training and progress. Check your BMI and body fat, work out your daily calories and macros, plan running paces and heart rate zones, estimate your one rep max, and track your results over time. Every tool works in metric and imperial, runs in your browser, and never stores your data.
Zero Health Tracking
Inputs stay in local browser memory
Instant Live Maths
Instant results with metric & imperial
Peer-Reviewed Equations
WHO, CDC, ACSM & Mifflin-St Jeor
Most Popular Calculators
The most frequently used tools for daily nutrition, body stats, and training.
BMI Calculator
Calculate your Body Mass Index in metric or imperial, with CDC youth LMS percentiles and Asian cut-offs.
TDEE Calculator
Estimate your Total Daily Energy Expenditure and discover your true maintenance calories.
Calorie Deficit Calculator
Calculate a safe, sustainable calorie deficit to reach your goal weight on schedule.
Macro Calculator
Calculate your daily macronutrients (protein, carbs, and fat) for weight loss or muscle building.
One Rep Max Calculator
Estimate your 1RM for bench, squat, and deadlift using Epley, Brzycki, Lander, and 4 other formulas.
Running Pace Calculator
Calculate pace, time, or distance for running with splits for 5K, 10K, half marathon, and marathon.
Body & Weight Calculators
Check where you stand today: BMI, body fat, ideal weight, lean body mass, fat-free mass, and central adiposity ratios.
BMI Calculator
Calculate your Body Mass Index in metric or imperial, with CDC youth LMS percentiles and Asian cut-offs.
BMR Calculator
Calculate your Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle.
TDEE Calculator
Estimate your Total Daily Energy Expenditure and discover your true maintenance calories.
Ideal Weight Calculator
Find your healthy body weight range based on BMI, Devine, Robinson, Miller, and Hamwi formulas.
Body Fat Calculator
Estimate your body fat percentage using the US Navy tape method or Deurenberg BMI equation.
Lean Body Mass Calculator
Calculate your lean body mass from height and weight using Boer, James, and Hume formulas or body fat %.
Waist-to-Height Ratio Calculator
Keep your waist to less than half your height. Check your WHtR and health risk category instantly.
Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio and check your cardiovascular risk against official WHO cut-offs.
Fat-Free Mass Calculator
Calculate your fat-free mass and FFMI from weight, height and body fat %. See your normalized FFMI.
Calorie & Nutrition Calculators
Calculate calories for weight loss, maintenance, or bulking, and split them into protein, carbs, fats, fiber, and water.
Calorie Calculator
Calculate your daily calorie needs for weight loss, maintenance, or muscle gain.
Calorie Deficit Calculator
Calculate a safe, sustainable calorie deficit to reach your goal weight on schedule.
Macro Calculator
Calculate your daily macronutrients (protein, carbs, and fat) for weight loss or muscle building.
Protein Calculator
Calculate your daily protein requirements based on body weight, fitness goals, and training intensity.
Water Intake Calculator
Calculate your optimal daily fluid intake based on body weight, workout intensity, and climate.
Calorie Surplus Calculator
Calculate your bulking calories and macro breakdown for clean muscle gain without excess fat.
Carbohydrate Intake Calculator
Calculate your daily carbohydrate requirements by percentage of calories or athlete training load.
Fat Intake Calculator
Find your daily fat intake in grams, including your saturated fat limit, based on calories.
Fiber Intake Calculator
Calculate your recommended daily fiber intake by age, sex or calories, with whole food sources.
Workout & Training Calculators
Plan smarter workouts: one rep max, training volume tonnage, target heart rate zones, VO2 max, METs, and calorie burn.
One Rep Max Calculator
Estimate your 1RM for bench, squat, and deadlift using Epley, Brzycki, Lander, and 4 other formulas.
Heart Rate Zone Calculator
Calculate your 5 cardiovascular training zones and Zone 2 endurance range using Tanaka or Karvonen HRR.
Walking Calories Burned Calculator
Calculate calories burned walking with the ACSM walking equation, incline grade, and backpack load.
Cycling Calories Burned Calculator
Calculate cycling calories burned from speed and terrain, or with high precision from power meter watts.
Target Heart Rate Calculator
Find your target heart rate window for moderate or vigorous cardio training using Tanaka or Karvonen.
VO2 Max Calculator
Estimate your VO2 max from the Cooper 12-min run, 1.5-mile test, Rockport walk, or resting HR.
METs Calculator
Calculate energy burned across 80+ activities using official 2024 Compendium MET codes and WHO targets.
Training Volume Calculator
Calculate workout volume load and weekly sets per muscle group vs hypertrophy standards.
Running & Cardio Calculators
Pacing, splits, grade-adjusted pace, running distance solver, and race finish predictions from 5K to marathon.
Running Pace Calculator
Calculate pace, time, or distance for running with splits for 5K, 10K, half marathon, and marathon.
Race Time Predictor
Predict finish times and paces for 1 Mile, 5K, 10K, Half Marathon, and Marathon with Pete Riegel's formula.
Running Calories Burned Calculator
Calculate calories burned running by weight, pace, duration, and treadmill incline using ACSM equations.
Running Distance Calculator
Calculate how far you ran from time and pace, track laps or step count.
Running Split Calculator
Plan your race splits for any distance and goal time with even or negative splits and pace band print.
Grade-Adjusted Pace Calculator
Convert uphill and downhill running pace to flat-ground equivalent using the Minetti energy model.
Strength & Performance Calculators
Strength standards, 1RM equations, strength-to-weight ratios, rest interval timers, and cross-bodyweight Wilks scoring.
Bench Press 1RM Calculator
Calculate your bench press one rep max, strength-to-bodyweight ratio, and strength standards.
Squat 1RM Calculator
Calculate your barbell squat 1RM, strength-to-weight ratio, and strength standards from beginner to elite.
Deadlift 1RM Calculator
Calculate your deadlift one rep max, strength-to-bodyweight ratio, and standards for conventional or sumo.
Wilks Score Calculator
Calculate your Wilks score, DOTS points, and IPF GL points to compare lifters across weight classes.
Strength-to-Weight Ratio Calculator
Calculate your strength-to-bodyweight ratio for bench, squat, deadlift or pull-ups.
Rest Time Calculator
Find the right rest between sets for strength, muscle growth or endurance with a built-in timer.
Progress Tracking Calculators
Track weight loss percentage, body recomposition, goal weight preservation, deficit timelines, and progressive overload.
Weight Loss Timeline Calculator
Project your realistic week-by-week weight loss timeline with adaptive metabolic rate tracking.
Weight Loss Percentage Calculator
Calculate the percentage of body weight you have lost and track clinical health milestones (5%, 10%, 15%).
Goal Weight Calculator
Set a realistic goal weight from a target BMI, body fat percentage or percent reduction.
Body Recomposition Calculator
Plan a body recomposition: calories, protein, and timeline to lose fat while gaining muscle.
Calorie Deficit Timeline Calculator
Find how many days and weeks it takes to lose weight at different daily calorie deficits.
Workout Progress Calculator
Calculate workout progress percentage for weight lifted, reps, time or distance with overload target.
How Our Health & Fitness Calculators Work
Every calculator in our suite is developed using published, peer-reviewed clinical algorithms and standardized international guidelines. We do not use proprietary black-box algorithms or arbitrary formulas.
- Body Weight & Composition: Evaluated using official World Health Organization (WHO) BMI brackets, CDC LMS age-and-sex percentiles for minors aged 2–19, Asian BMI risk cutoffs, and the US Navy circumference equations.
- Energy Expenditure & Metabolism: Computed using the Mifflin-St Jeor equation (the clinical standard recognized by the Academy of Nutrition and Dietetics) alongside the Katch-McArdle formula for lean mass.
- Progress Simulations: Powered by dynamic metabolic adaptation models rather than naive static rules, accounting for declining energy expenditure as body weight drops.
- Client-Side Engine: All calculations execute in local JavaScript inside your browser. No personal demographic or health metrics are ever transmitted or saved.
Frequently Asked Questions
Are these health and fitness calculators accurate?
Every calculator uses clinically validated, peer-reviewed scientific formulas including the Mifflin-St Jeor equation, WHO BMI classifications, CDC LMS growth charts, ACSM exercise guidelines, and the US Navy body fat method. While formulas provide high-precision mathematical estimates, they are screening tools rather than clinical diagnostic measurements.
Are these calculators completely free?
Yes, 100% free with no account creation, no subscriptions, and no paywalls. All mathematical operations execute directly in your web browser.
Is my personal health data stored or sent to a server?
No. Unlike other calculator websites that capture health parameters for advertising profiles, FlexibleToolsAI executes every formula locally on your device. Your age, weight, height, and biological sex never leave your browser.
Can I use these calculators instead of consulting a doctor?
No. These tools provide mathematical estimates for educational and self-quantification purposes only. They cannot diagnose medical conditions, prescribe clinical diets, or replace the direct advice of a registered physician, dietitian, or physiotherapist.