gentle tools for your parenting journey

Pregnancy Weeks to Months

Pregnancy is tracked in weeks, but everyone still asks "how many months is that?" Enter your week or due date and we'll tell you — month, trimester and all.

You are in
weeks pregnant
trimester
Pregnancy months don't split evenly into 4-week blocks — a full-term pregnancy is about 40 weeks, which is closer to 9 months of roughly 4–5 weeks each. That's why "month 3" and "13 weeks" can both be correct at the same time.

Full weeks-to-months chart

WeeksMonthTrimester
1–4Month 11st
5–8Month 21st
9–13Month 31st
14–17Month 42nd
18–22Month 52nd
23–27Month 62nd
28–31Month 73rd
32–35Month 83rd
36–40+Month 93rd

Curious about exact upcoming dates instead of weeks? Try the Weeks From Today Calculator.

Common questions

How many weeks are in a pregnancy month?

It varies. Because a full-term pregnancy runs about 40 weeks over 9 months, most months work out to around 4–5 weeks rather than a flat 4. That's why week and month counts don't line up as neatly as you'd expect.

Why don't pregnancy months split evenly into 4-week blocks?

40 weeks divided evenly into 4-week months would only total 8 months, not 9 — so the extra weeks get spread across the calendar, giving some months 4 weeks and others 5. There's no single official standard, which is why you'll see slightly different week ranges from different sources.

How many weeks are in each trimester?

The first trimester covers weeks 1–13, the second covers weeks 14–27, and the third runs from week 28 until birth, typically around week 40.

How do I calculate my month from my due date?

Count backward from your due date in 7-day blocks to find how many weeks pregnant you are today, then match that week number to the chart above. Or just enter your due date in the calculator on this page and we'll do it for you.