Health Calculators.

The Age Calculator works out your exact age in years, months and days from a date of birth and an optional "as of" date, then goes further: total days, weeks, hours and minutes lived, the weekday you were born on, and a live countdown to your next birthday. It handles month lengths and leap years correctly, so "31 days in January" never skews the result.

Use it for birthdays & milestoneseligibility checksforms & applicationstrivia & fun

Body Mass Index divides your weight by your height squared. The calculator accepts metric (kg · cm) or imperial (lb · ft/in), returns your category — underweight, healthy, overweight or obese — and the healthy weight range for your exact height, so you can see not just the label but the target.

Use it for general screeningfitness baselinesweight goalsclinical reference

Basal Metabolic Rate is the energy your body burns at complete rest — just to breathe, circulate blood and keep you warm. This tool uses the Mifflin-St Jeor equation, the formula most dietitians consider the most accurate, and cross-checks it against the classic Harris-Benedict equation so you can see both estimates side by side.

Use it for diet planningmetabolism checkscutting & bulkingclinical nutrition

Estimates body fat percentage with the U.S. Navy circumference method — the same tape-measure technique used in military fitness testing. Enter neck and waist (plus hip for women) and it returns your percentage, your category, and the split between fat mass and lean mass in kilograms.

Use it for body recompositionprogress trackingmilitary fitness prepleaning out

Computes a daily hydration target from your body weight — 35 ml per kg as the baseline — then adds 350 ml for every 30 minutes of exercise. The result is shown in litres, in 250 ml glasses and in 500 ml bottles, so "drink more water" finally becomes a countable number.

Use it for daily hydration goalstraining dayshabit buildingoffice reminders

Multiplies your BMR by an activity factor — from sedentary (×1.2) to athlete (×1.9) — to find the number of calories that keep your weight exactly where it is. From there it derives gentle and steady loss targets, gain targets, and daily protein and carbohydrate grams for a balanced 30/40 split.

Use it for weight loss planslean bulkingmacro targetsmaintenance days

From the first day of your last menstrual period and your cycle length, it computes gestational age in weeks and days, the current trimester, the estimated due date and the estimated conception date, plus a live progress percentage across the full 40-week timeline. Cycle lengths other than 28 days shift the due date accordingly.

Use it for week-by-week trackingtrimester planningappointment prepsharing updates

Ovulation happens about 14 days before the next period, whatever your cycle length. This tool counts back from your projected next period to find the ovulation day, then marks the six-day fertile window (five days before plus the day after) and tells you which cycle day you're on right now.

Use it for conception planningcycle awarenessfertility trackinghealth journaling

Estimates your delivery date by Naegele's rule — 280 days after the last menstrual period — or, if you know it, from the conception date (+266 days) or an IVF transfer date (day-3: +263, day-5: +261). It also works backwards from the due date to give the equivalent LMP and current gestational age.

Use it for delivery planningmaternity leave timingIVF schedulingnursery prep