Due Date Calculator
This due date calculator estimates when your baby is likely to arrive and shows
This due date calculator estimates when your baby is likely to arrive and shows
How to use Due Date Calculator
- Choose whether to calculate from your last period, conception date, or IVF transfer date.
- Enter the relevant date, and for the last-period method set your average cycle length.
- Read your estimated due date, how far along you are, and the milestone timeline.
About Due Date Calculator
This due date calculator estimates when your baby is likely to arrive and shows how far along you are today. It supports three starting points: the first day of your last menstrual period (LMP), an estimated conception or ovulation date, or an IVF embryo transfer date. For the LMP method it uses Naegele's rule (last period plus 280 days) and adjusts the estimate when your average cycle length differs from the standard 28 days.
Along with the estimated due date, it calculates your current gestational age in weeks and days, your trimester, days remaining, the percentage of the pregnancy elapsed, an estimated conception date, and a short timeline of common milestones such as the anatomy-scan window and the start of full term.
These are estimates for planning, not medical advice. Only about 4% of babies are born on the exact due date, and most arrive within two weeks on either side. An early ultrasound and your provider's own dating always take precedence. Everything is computed locally in your browser — the dates you enter are never uploaded or stored.
Frequently asked questions
- How is the due date calculated?
- For the last-period method it adds 280 days (40 weeks) to the first day of your last menstrual period, following Naegele's rule, and shifts the result if your cycle is longer or shorter than 28 days. For a conception date it adds 266 days; for IVF it counts from the embryo's age at transfer (261 days for a 5-day blastocyst, 263 for a 3-day embryo).
- How accurate is a due date calculator?
- It gives a solid estimate, but a due date is never a guarantee. Only around 4% of babies arrive on the exact date, and roughly 80% are born within two weeks before or after. Cycle irregularity affects the last-period method, so an early-pregnancy ultrasound is usually the most accurate way to date a pregnancy.
- What if my cycle isn't 28 days?
- When you use the last-period method, enter your average cycle length. Ovulation, and therefore conception, tends to happen about 14 days before your next period, so the tool moves the estimated due date later for longer cycles and earlier for shorter ones.
- Can I use it for an IVF pregnancy?
- Yes. Choose the IVF 5-day or 3-day transfer option and enter your transfer date. Because the embryo's age is known precisely, IVF due dates are typically more accurate than last-period estimates.
- Is my information private?
- Yes. The calculator runs entirely in your browser using JavaScript. The dates you enter are never sent to a server, saved, or shared with anyone.
- How do I count how far along I am?
- Pregnancy is measured in weeks of gestational age starting from the first day of your last period, which is about two weeks before conception. The tool shows your progress as weeks plus days (for example, 8w 3d) and tells you which trimester you're in.