Health Calculators

BMI, TDEE, Due Date, Ovulation, Dog Age and Pet Food Calculators

Two of the most-used numbers in health and fitness, calculated from the standard published formulas and explained honestly. Both accept metric or imperial input, including heights typed as 5'10", and both run entirely on your device so your weight never leaves it.

Most used this week

BMI Calculator For Women

BMI for women with the healthy range and a female BMI chart.

BMI Calculator For Men

BMI for men with the healthy range and a male BMI chart.

Every Health tool

BMI Calculator

Body mass index from metric or imperial height and weight.

BMI Calculator For Men

BMI for men with the healthy range and a male BMI chart.

BMI Calculator For Women

BMI for women with the healthy range and a female BMI chart.

BMI Calculator Kg Cm

Metric BMI from kilograms and centimetres, formula included.

Baby Age Calculator

Baby's age in weeks and months, with corrected age for preemies.

Child And Teen BMI Calculator

BMI percentile for ages 2 to 20 by the CDC growth chart method.

Child Height Predictor

Predicted adult height from parents' heights, in ft/in or cm.

Conception Date Calculator

Likely conception date from a due date, birth date or last period.

Cycling Speed Calculator

Average speed from a ride, or road speed from cadence and gearing.

Dog Pregnancy Calculator

Whelping or kittening date and birth window from the mating date.

Heart Rate Zone Calculator

Five training zones from age, max heart rate and resting heart rate.

IVF Due Date Calculator

Due date from a day 3, 5 or 6 embryo transfer or egg retrieval.

Running Pace Calculator

Pace per km and mile, finish times and race predictions at the same pace.

Steps To Distance Calculator

Steps to km or miles and back, from your height or measured stride.

BMI

Body mass index is weight in kilograms divided by height in metres squared. The calculator does that conversion for you from whatever units you have, shows the resulting figure and which of the standard World Health Organization categories it falls into, and shows the weight range that would correspond to the "normal" band for your height. That last figure is often the more useful one, because it turns an abstract index into something you can act on.

BMI is a population screening measure, not a diagnosis. It does not distinguish muscle from fat, it was calibrated on adults, and the thresholds are debated for some ethnic groups and for older people. The page says this plainly. It is a starting point for a conversation with a doctor, and a reasonable way to track your own trend over time, and nothing more.

TDEE

Total daily energy expenditure estimates how many calories you burn in a day: a basal metabolic rate from your age, sex, height and weight, multiplied by an activity factor. The calculator uses the Mifflin-St Jeor equation, which performs best in comparisons against measured values, and shows the result for each activity level so you can see how much the choice of level moves the number — it moves it a lot, and most people overestimate their activity.

The output includes the maintenance figure and typical deficit and surplus targets. Treat these as a first estimate to adjust against what the scales actually do over a few weeks, which is the only measurement that matters.

Pregnancy dates

The due date calculator adds the standard 280 days to the first day of the last period, adjusted for cycle length, or 266 days to a known conception date, and shows how many weeks along today is, the trimester and the full-term window. The ovulation calculator places ovulation a luteal phase before the next expected period and marks the six-day fertile window, projected over the next six cycles. Both are calendar arithmetic; a dating scan and the people looking after the pregnancy have the final word.

Pets

The pet age calculator converts a dog's or cat's age to a rough human equivalent with the staged method vets use, fast for the first two years and size-dependent after, rather than multiplying by seven. The pet food calculator works out daily energy from weight and life stage with the standard 70 × kg^0.75 formula and converts it to cups or grams of the food on hand from the calories printed on the bag. Neither offers dietary or veterinary advice; they show the arithmetic the feeding guides and age charts are built on.

Where the formulas stop being reliable

Both tools state their limits on the page: BMI for children, athletes and the elderly; TDEE for anyone whose body composition is far from average. Neither replaces advice from a clinician who can see you.

Privacy

Height, weight, age and sex are exactly the details you do not want logged by a website. Nothing entered here is sent to a server, stored, or shared; the calculation runs in your browser and is gone when you close the tab.