Pregnancy & Fertility Calculators
A connected set of tools for the whole journey — from tracking your fertile window to counting the weeks. Each one handles irregular cycles, multiple dating methods, and gives you real dates, not just a number.
Plan it step by step
Want to know when your next period is due? Predict your next periods and today's cycle phase.
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.
Trying to conceive? Find your fertile window and the best days, even with irregular cycles.
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).
Already have a due date? Work backwards to find the most likely day you conceived.
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.
Got a positive test? Estimate your due date from your last period, conception, IVF transfer, or an ultrasound.
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.
Already pregnant? See exactly how many weeks and days along you are, plus your prenatal appointment schedule.
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.
Pregnant and watching your weight? See the recommended gain for your pre-pregnancy BMI and if you're on track.
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.
Following early blood tests? Calculate your hCG doubling time and rise between two results.
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.
How these calculators work
Due dates and gestational age are conventionally counted from the first day of the last menstrual period (LMP), assuming ovulation around day 14 — so the same 40-week timeline links ovulation, conception, and your current week. Where you know a more precise date (an early ultrasound, a known conception or IVF transfer), these tools use it and reconcile the difference, because early-ultrasound dating is more accurate than LMP for irregular cycles.
These calculators give estimates for planning and education only. They are not medical advice and don't replace your doctor or midwife. Only about 1 in 20 babies arrive on the exact due date.