Free Health & Fitness Calculators

Body composition, energy needs, training zones and pacing — each explaining which formula it uses and where that formula stops being reliable.

58 free tools
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Most visited in Health & Fitness

Running Pace Calculator Free pace calculator — pace per km/mile and speed for any distance and time. Steps to Miles Calculator Convert your step count into accurate miles and km using your real height-based stride. BMR Calculator Calculate your Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle. Pregnancy Due Date Calculator Estimate your due date, current week, trimester, and conception date instantly.

Ordered by how often these pages are shown in Google Search results. Every tool in the category is listed in full below.

A 2 tools

A1C Calculator Convert A1C percentage to estimated average glucose (eAG) or the reverse, in mg/dL and mmol/L. Alcohol Units Calculator Convert drink volume and ABV into US standard drinks, UK units, and pure alcohol grams.

B 9 tools

Baby Percentile Calculator Estimate your baby's weight and height percentile from simplified growth-chart bands. BAC Calculator Estimate blood alcohol content from drinks, weight and time using the Widmark formula. Blood Pressure Calculator Enter your systolic and diastolic numbers to see your ACC/AHA blood pressure category instantly. Blood Sugar Converter Convert blood glucose between mg/dL and mmol/L with target-range context. BMI Calculator Find your Body Mass Index and see which weight category you fall into — free and private. BMR Calculator Calculate your Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle. Body Fat Calculator Estimate body fat percentage with the proven U.S. Navy tape-measurement method — free. Body Recomposition Calculator Get target weight, calories, and protein for losing fat while preserving muscle. Body Surface Area Calculator Estimate your BSA in m² using Du Bois, Mosteller, and Haycock clinical formulas.

C 6 tools

Caffeine Calculator Add up your coffee, tea, and energy drinks to see total daily caffeine vs. the 400mg limit. Calorie Deficit Calculator Turn your weight-loss goal and timeframe into a safe daily calorie target. Calories Burned Calculator Estimate calories burned for 20+ activities using MET values and your body weight. Child Height Predictor Predict your child's adult height range using mom and dad's height (mid-parental method). Conception Date Calculator Estimate your baby's conception date from a due date, birth date, or last period. Cycling Calorie Calculator Estimate calories burned cycling from your weight, duration, and intensity.

F 3 tools

Fasting Timer Track an active fast: elapsed time, remaining time, end time, and metabolic stage. Fertility Calculator Find your fertile window and best days to try to conceive this cycle. FFMI Calculator Calculate your Fat-Free Mass Index and see how it compares to the natural muscle ceiling.

H 1 tool

Heart Rate Zone Calculator See all 5 heart rate training zones from recovery to max effort in one view.

I 2 tools

Ideal Weight Calculator Compare Devine, Robinson, Miller, and Hamwi formulas to find your healthy weight range. Intermittent Fasting Calculator Build your exact eating and fasting window for 16:8, 18:6, 20:4, OMAD, or 5:2.

K 1 tool

Keto Calculator Get your daily calories plus a fat, protein, and net-carb split built for a ketogenic diet.

L 1 tool

Lean Body Mass Calculator Find your lean body mass, fat mass, and body fat percentage using the Boer formula.

M 5 tools

Macro Calculator Get your daily calorie, protein, carb, and fat targets based on your body stats and goal. Maintenance Calorie Calculator Find the exact calories that keep your weight flat, using BMR and activity level. Marathon Time Predictor Predict your marathon finish time from a recent 5K, 10K, or half marathon using Riegel's formula. Max Heart Rate Calculator Estimate your max heart rate with three formulas plus your 50-85% training range. Menopause Calculator Estimate your likely perimenopause window and menopause age from age, family history, and smoking.

O 2 tools

One Rep Max Calculator Estimate your one-rep max from any set using Epley, Brzycki, or Lombardi formulas. Ovulation Calculator Estimate your ovulation date, fertile window, and most fertile days from your last period.

P 4 tools

Pace Converter Convert running pace between min/mile, min/km, mph, and km/h instantly. Period Calculator Predict your next period, cycle day, and fertile window from your last period date. Pregnancy Due Date Calculator Estimate your due date, current week, trimester, and conception date instantly. Pregnancy Week Calculator Find out exactly how many weeks and days pregnant you are, your trimester, and your due date.

R 2 tools

Running Calorie Calculator Estimate calories burned running from your weight, distance, and pace. Running Pace Calculator Free pace calculator — pace per km/mile and speed for any distance and time.

S 8 tools

Sleep Cycle Calculator Find the ideal bedtime or wake time based on 90-minute sleep cycles so you wake up refreshed. Sleep Time Calculator See how much sleep is recommended for your age and compare it to your actual sleep and weekly debt. Smoking Cost Calculator Calculate the true daily, monthly, and lifetime cost of smoking — plus what you'd have if you invested it instead. Sobriety Calculator Count your days sober, hit milestones, and see the money you've saved. Steps to Calories Calculator Convert your daily steps into estimated calories burned, distance, and per-1,000-step rate. Steps to Miles Calculator Convert your step count into accurate miles and km using your real height-based stride. Sugar Intake Calculator Add up your daily added sugar and compare it to the AHA and WHO recommended limits. Swimming Calorie Calculator Estimate calories burned swimming based on your weight, duration, and stroke or intensity level.

T 3 tools

Target Heart Rate Calculator Get a personalized target heart rate using the Karvonen heart-rate reserve method. TDEE Calculator Find how many calories your body burns daily and how many to eat for your goal — free. Treadmill Pace Calculator Convert treadmill mph/km-h and incline into pace and outdoor-equivalent effort.

V 1 tool

VO2 Max Calculator Estimate your VO2 max using resting HR, 1.5-mile run, Cooper, or Rockport walk tests.

W 8 tools

Waist to Height Ratio Calculator Find your waist-to-height ratio and see if your waist is under half your height. Waist to Hip Ratio Calculator Get your WHR, WHO risk category, and apple vs. pear body shape from waist and hip measurements. Walking Calorie Calculator See how many calories you burn walking, by distance, time, pace and body weight. Water Intake Calculator Personalised daily water intake calculator by weight, activity and climate. Water Weight Calculator Estimate your total body water in liters and see why daily scale swings are usually water, not fat. Weight Loss Calculator Project the weeks and date you'll reach your goal weight at your current pace. Weight Loss Percentage Calculator Find the percentage of body weight you've lost and your progress toward goal. Wilks Calculator Calculate your Wilks score to compare powerlifting strength fairly across bodyweights.

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Every formula is named

There is no single correct way to estimate body fat, resting metabolism or maximum heart rate; there are several published equations that disagree with each other. These tools state which one they use — Mifflin-St Jeor, US Navy circumference, Karvonen — because a number without its method cannot be compared with a number from anywhere else.

Where the estimates break down

BMI does not distinguish muscle from fat and was never designed to assess an individual. Predictive maximum-heart-rate formulas carry a standard deviation of roughly ten beats per minute. Calorie estimates assume an average that describes very few actual people. Each page says so, because a tool that presents an estimate as a measurement is misleading regardless of how well it calculates.

Information, not advice

These pages explain how a calculation works and what its output means. None of them tells you what to eat, how to train, or whether a result is a problem — those are questions for a qualified professional who can see your full picture. Every page in this set carries that statement explicitly.

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