Free health & fitness calculators — BMI, body fat, calories, BMR
Every calculator here turns a number you can measure at home into something you can act on. BMI and body-fat estimates that flag where you actually stand, a BMR and calorie calculator that sets a daily target instead of a vague goal, ideal-weight and one-rep-max tools for training. No signup, no app — just the formula, the result, and what it means.
BMI Calculator (metric & imperial, with category)
Calculate your Body Mass Index in metric or imperial units, with category interpretation.
Calorie Calculator (BMR & TDEE, Mifflin-St Jeor)
Estimate your daily calorie needs using the Mifflin-St Jeor BMR formula and an activity multiplier. Includes targets for weight loss and gain.
Ideal Weight Calculator (Devine, Robinson, Miller, Hamwi)
Estimate ideal body weight using four classic clinical formulas plus the WHO healthy BMI range. Choose by height and sex.
Due Date Calculator — LMP, IVF, ultrasound or conception
Estimate your due date from your last period (with cycle-length adjustment), conception, an IVF transfer (day 3 or 5), or an ultrasound. Shows the full-term 37–42 week window and current gestational age.
Conception Date Calculator — from due date or birth date
Work backwards to estimate when you conceived — from your due date or your baby's birth date. Shows the most likely conception day, a conception window, and the likely intercourse dates.
Period Calculator — next 6 periods & cycle phase
Predict your next six periods, see today's cycle day and phase, your fertile window, and export the dates to your calendar — from your last period, cycle length, and period length.
Pregnancy Weight Gain Calculator — by pre-pregnancy BMI
See your recommended pregnancy weight gain based on your pre-pregnancy BMI and the IOM guidelines — the full-term range, how much to have gained by your current week, and whether you're on track.
hCG Calculator — doubling time & rise from two values
Enter two quantitative hCG blood results and their dates to calculate the doubling time, the 48-hour rise, and the daily rise — a tool for understanding early-pregnancy hCG trends, not a diagnosis.
Water Intake Calculator (daily target by weight)
Estimate your recommended daily water intake based on body weight and activity level. Shown in liters, ounces, cups, and bottle equivalents.
Running Pace Calculator (time, pace, speed)
Calculate running pace from distance and time, or finish time from a target pace. Output per-km, per-mile, km/h, and mph.
Macro Calculator (P/F/C grams from TDEE and goal)
Calculate daily protein, fat, and carb targets from your TDEE and weight goal. Uses 30/30/40 split with a protein floor of 1.6 g/kg.
BMR Calculator (Mifflin, Harris-Benedict, Katch-McArdle)
Calculate basal metabolic rate via three formulas: Mifflin-St Jeor (default), Harris-Benedict (legacy), and Katch-McArdle (uses lean mass).
Ovulation Calculator — fertile window for irregular cycles
Find your ovulation date and fertile window even with irregular cycles. See your next 6 fertile windows, the earliest reliable test date, and export the days to your calendar (.ics).
Body Fat Calculator (US Navy Method)
Estimate body fat percentage using the US Navy method (waist, neck, and hip for women). Returns fat mass, lean mass, and fitness category.
Pregnancy Week Calculator — weeks + prenatal schedule
See exactly how many weeks and days pregnant you are — from your last period or an ultrasound — plus fetal age, trimester, due date, and your prenatal appointment schedule with real dates.
One-Rep Max Calculator (5 formulas + percent table)
Estimate your 1RM (one-rep max) from any submaximal lift. Five validated formulas (Epley, Brzycki, Lombardi, O'Conner, Lander) plus a training-percentage table.
Target Heart Rate Calculator (5 training zones)
Calculate your max heart rate and 5 training zones (recovery, fat burn, aerobic, threshold, max). Karvonen formula uses resting HR for accuracy.
Weight Loss Calculator (timeline + target date)
Calculate how long it takes to reach your target weight at a given daily calorie deficit. Returns target date, weeks, months, and weekly weight loss.
Waist-to-Hip Ratio Calculator (cardiovascular risk)
Calculate WHR (waist circumference / hip circumference). Categorizes risk level by sex per WHO thresholds.
Sleep Calculator — Find Your Ideal Bedtime or Wake-Up Time
Calculate the best bedtime or wake-up time based on 90-minute sleep cycles.
Blood Pressure Checker — AHA 2017 Categories Explained
Enter your systolic and diastolic pressure to get your AHA category, pulse pressure, and plain-English advice.
Exercise Calorie Calculator — MET-based calories burned
Calculate calories burned during exercise using MET values. Supports 18 activities, kg/lbs, and shows fat burned.
Steps to Distance Calculator — km, Miles, Calories & Time
Convert step count to distance in km or miles. Estimates walking time and calories burned based on your height, stride length, and weight.
Calorie Deficit Calculator — TDEE & Weight Loss
Find your daily calorie deficit to lose weight safely. Uses Mifflin-St Jeor BMR and your activity level to set a realistic target.
Protein Intake Calculator – Daily Grams
Estimate your daily protein needs from body weight and activity.
Waist-to-height ratio calculator
Calculate your waist-to-height ratio (WHtR) from waist and height in cm.
Body Surface Area Calculator (BSA)
Estimate body surface area (BSA) in m² using the Mosteller formula.
A1C to Average Glucose Calculator (eAG)
Convert your HbA1c percentage into estimated average glucose in mg/dL and mmol/L.
Ponderal Index Calculator (kg/m³)
Calculate your ponderal index from height and weight.
Maximum Heart Rate Calculator (by Age)
Estimate your maximum heart rate from your age in beats per minute (bpm).
Dog Age Calculator — Convert Dog Years to Human Years
Convert your dog's age into human-equivalent years instantly.
Cat Age Calculator - Cat Years to Human Years
Convert your cat's age into human-equivalent years instantly.