How Many Weeks Pregnant Am I?

Enter the first day of your last period and find out exactly where you are today — weeks, days, trimester and all.

"How many weeks pregnant am I?" is counted from the last period, not from conception, which is why the number is about two weeks ahead of the embryo's actual age. This calculator shows both views.

First day of your last period

Your usual cycle length (days)

Used only to estimate your conception date.

Today you are approximately

Trimester

Estimated due date

Days remaining (estimate)

Estimated conception

Please read: This calculator gives estimates only — it is not medical advice and cannot diagnose or date a pregnancy with certainty. Only around 5% of babies arrive on their estimated due date, and most arrive within a week or so either side. Ultrasound dating performed by a clinician takes precedence over any calculator result. Always confirm your dates, screening windows and care plan with your healthcare provider. All dates are processed locally in your browser; nothing you enter is uploaded or stored.

Weeks, days and trimesters

Gestational age is written as weeks plus days — 20 weeks, 4 days, for example — and it ticks over at the same weekday as your period started. The first trimester runs through 13 weeks, 6 days; the second through 27 weeks, 6 days; the third from 28 weeks until birth. "Full term" is generally used from 37 weeks, and 40 weeks is the estimated due date — an average, with most babies arriving in the weeks around it.

If your cycle is much longer or shorter than 28 days, or your dates are uncertain, an early ultrasound may give your provider a different — and usually more trusted — figure. See how due dates are calculated for the reasoning, or browse the week-by-week timeline.