If I got pregnant this month, when would I be due? Due dates by month

If I got pregnant in a certain month, when would I be due?

Conception happens at, or within a day of, ovulation. A pregnancy lasts on average 266 days from conception, which is the same as the familiar 280 days (40 weeks) counted from the first day of your last period, because ovulation usually comes about two weeks after that period starts. So the rule of thumb is: add nine months to the conception date, then take away about a week.

Due date by conception month table

Each row adds 266 days to the first and last day of the month you conceived. Leap years can move a date by one day.

How the due date calculator above works

Most people don't know the exact day they conceived, so doctors date a pregnancy from the first day of your last period (LMP). The calculator above uses that date and your usual cycle length:

1. It adds 280 days (40 weeks) to the first day of your last period.
2. If your cycle is longer or shorter than 28 days, it shifts the date by the difference, because you probably ovulated later or earlier than day 14. A 32-day cycle adds 4 days; a 25-day cycle takes away 3.
3. It also shows how many weeks and days pregnant you'd be today.

If you know when you ovulated or conceived, for example from a positive LH test, use our due date calculator from ovulation, which adds 266 days directly. To go the other way, from a due date back to conception, try the conception calculator.

Worked example

Say you think you conceived around 10 March. Adding 266 days gives a due date of about 1 December. In LMP terms, your last period would have started around 24 February, and 24 February plus 280 days also lands on 1 December. If your cycles are 32 days instead of 28, you probably ovulated later, so a dating scan may move the date by a few days.

How accurate is a due date by month?

• It's an estimate. Only a small share of babies arrive on their due date. Most come within about two weeks either side.
• Conception month is a range. Sex up to five days before ovulation can lead to pregnancy, so even a known date of sex leaves a few days of uncertainty.
• An early ultrasound wins. ACOG recommends confirming the due date with an ultrasound in the first trimester, and the scan date is used if it differs enough from your LMP date.
• IVF is the exception. With an embryo transfer the date is known precisely, so use the IVF due date calculator.

Feelings in early pregnancy

Finding out can bring joy, nerves, or a mix of both, and rising hormones in the first weeks often feel a lot like strong PMS: tiredness, tender breasts and mood swings. Be patient with yourself. If you're not sure yet whether you're pregnant, our guide on when to take a pregnancy test explains when a result is reliable.

When to see a doctor or midwife