Pregnancy & Family Calculators

Two of the most-searched calculators on the internet, done right. Estimate your due date from your last period, conception date, or IVF transfer — then see your trimester, days remaining, and what to expect each week. The ovulation calculator maps your fertile window from your cycle length. Private by design: everything runs in your browser, nothing is uploaded.

From dates to a due date

Pregnancy is measured in gestational age — weeks since the first day of your last period, not since conception. That is why the standard pregnancy is "40 weeks" even though conception happens around week 2. Enter your dates and the calculator handles the arithmetic, including which trimester you are in and how many days remain.

Understanding your fertile window

Pregnancy is possible during roughly six days each cycle: the five days before ovulation (sperm can survive that long) plus ovulation day itself. The ovulation calculator estimates ovulation as 14 days before your next expected period and highlights the full window on a calendar — but treat it as a planning estimate, not a contraceptive method.

Frequently asked questions

How is a due date calculated?

The standard Naegele’s rule: add 280 days (40 weeks) to the first day of your last menstrual period. If you know the conception date instead, add 266 days. For a day-5 IVF embryo transfer, add 261 days.

How accurate are ovulation estimates?

They are estimates based on averages — ovulation typically occurs 14 days before your next period, but stress, illness, and natural variation shift it. Use ovulation predictor kits for precision when it matters.

Which trimester am I in?

First trimester: weeks 1–13. Second: weeks 14–27. Third: week 28 until birth. The due date calculator shows yours automatically.

Is my information private?

Yes. Every calculation happens in your browser — dates and cycle details are never sent to our servers.