Designed for real bodies · No tracking
Women's health calculators that actually get you.
Period, ovulation, due date, pregnancy week, BMI and body shape — with PCOS and irregular-cycle modes built in. Private by default, shareable when you want.
Pick your calculator
BMI Calculator
BMI calculator with adjustments for life stage — pregnancy, postpartum, menopause — and an age-adjusted view. Returns BMI, BMI Prime, Ponderal Index, healthy range and waist-to-hip-ratio.
Body Shape Calculator
Find your body shape with the FFIT 7-type system (Hourglass, Pear, Apple, Rectangle, Inverted Triangle, Spoon, Top Hourglass). Plus waist-to-hip ratio and outfit guidance per shape.
Due Date Calculator
Calculate your estimated due date by LMP, conception date, ultrasound (CRL or weeks+days) or IVF transfer (Day 3, 5, or 6). Plus current gestational age and key prenatal-visit dates.
Ovulation Calculator
Find your most fertile days, ovulation date and implantation window. Supports cycles 15–50 days and irregular-cycle prediction. Save fertile days to your calendar.
Period Calculator
Free period calculator with PCOS / irregular cycle modes. Predict your next 6 periods, ovulation, fertile window and luteal phase — with a shareable result card and zero tracking.
Pregnancy Week Calculator
Find out how many weeks pregnant you are, what trimester you’re in, and how weeks convert to months. Includes a fetal-size visual and a week-by-week milestone calendar.
Safe Period Calculator
A safe-period (rhythm method) calculator with a cycle-variation input for higher accuracy. Plus a clear chart of when this method does — and doesn’t — work.
Why HerCalc
PCOS
PCOS-aware by default
Every relevant calculator includes a PCOS / irregular-cycle mode so your prediction matches your real cycle, not a textbook 28-day average.
Privacy
No tracking, no accounts
Calculations run entirely in your browser. We do not store your dates, weight, or measurements on a server.
Methodology
Open methodology
Every tool has a public methodology page citing peer-reviewed sources: Naegele rule, ACOG guidance, ICMART/ESHRE protocols, FFIT classification.
Calendar
Calendar-ready exports
Add your fertile window or due-date milestones to Google or Apple Calendar with a single click. No email signup required.
Built for irregular cycles, PCOS, and life stages other apps ignore
The textbook 28-day cycle and "ovulation on day 14" assumption fails an estimated 30% of menstruating people. If you have PCOS, are perimenopausal, postpartum, breastfeeding, or just have cycles that don't fit a neat box, most calculators silently give you wrong numbers and no warning.
HerCalc treats those scenarios as defaults, not edge cases. Toggle Standard / Irregular / PCOS on the period and ovulation calculators. Get a confidence range when your cycle varies. See an explicit warning when calendar prediction alone is unreliable for your pattern.