How Far Along Am I? Pregnancy Week Calculator

14 weeks 6 days: week 14 or week 15?

This trips up almost everyone. “14 weeks 6 days” means you’ve completed 14 weeks and 6 days, so you’re now in your 15th week. Your provider glances at the chart and says “14 plus 6”; you get home and tell your partner “I’m in week 15.” Both describe the same day.

That’s why the calculator shows both. On lab forms and appointment notes, the completed weeks and days (14+6) are what’s usually asked for.

Why weeks are counted from your period

Pregnancy weeks are counted from the first day of your last period, not from conception. On the day you conceive, you’re already considered 14 days pregnant. Our due date calculator explains this, and how cycle length shifts it, in more detail.

Trimesters

Pregnancy is split into three trimesters. The calculator uses these boundaries:

• First trimester: from the start of pregnancy until the start of week 14
• Second trimester: from the start of week 14 until the start of week 28
• Third trimester: from the start of week 28 until birth

Some sources draw these lines a few days differently, which is why two websites can disagree about your trimester on the same day. Your week is what matters.

Why “how many months” is misleading

A month is anywhere from 28 to 31 days, so weeks don’t divide evenly into months. The same pregnancy can be “five months” to one person and “nearly six” to another. That’s why care is planned in weeks: tests, scans and vaccines are all timed by week. It’s fine to tell friends you’re “five months,” but know your week for appointments.

If your provider’s week doesn’t match

A first-trimester ultrasound dates a pregnancy more accurately than your period date. If your due date was adjusted after a scan, choose “Due date from your provider” so the calculator matches your care team’s dates exactly.

Planning ahead

“How far along will I be on…?” is one of the most common planning questions, whether it’s a flight, a wedding, an exam or the start of parental leave. Enter the date under “Calculate for another date” and the result and key dates table switch to that day. Airlines and employers set their own pregnancy rules by week, so check theirs directly when you plan.