Pregnancy Week Calculator — How Far Along Am I?
This pregnancy week calculator shows exactly how many weeks and days pregnant you are today — starting from either your last period or your due date — plus your current trimester and the milestones ahead.
Your dates
Your result
Your 40-week timeline
Based on Naegele's rule (ACOG methodology). Estimates only — always confirm with your provider.
How pregnancy weeks are counted
Pregnancy is counted from the first day of your last menstrual period (LMP) — so you're already "4 weeks pregnant" around the time you miss a period, even though conception happened about two weeks earlier. Weeks are always stated as completed weeks plus days: "12 weeks, 3 days" means you are in your 13th week. Following ACOG's convention, the first trimester runs through the end of week 13, the second through the end of week 27, and the third to birth, with full term reached at 39 weeks.
Worked example. If the first day of your last period was January 1, 2026, then on February 1, 2026 you are 4 weeks and 3 days pregnant (31 days ÷ 7), which places you in the first trimester. From that same LMP your estimated due date is October 8, 2026 (LMP + 280 days). The table below shows where the major milestones fall in a typical 40-week pregnancy:
| Stage | Weeks (from LMP) | Milestone |
|---|---|---|
| 1st trimester | Weeks 1–13 | Positive test ~week 4; heartbeat often seen ~week 6–8 |
| 1st → 2nd | Week 12–13 | End of first trimester; dating/NT scan around this time |
| 2nd trimester | Weeks 14–27 | Anatomy scan ~week 18–22; movement often felt ~week 18–22 |
| 2nd → 3rd | Week 28 | Third trimester begins |
| 3rd trimester | Weeks 28–36 | Rapid growth; more frequent prenatal visits |
| Full term | Weeks 39–40 | Considered full term at 39 weeks; due date at 40 weeks |
Milestone weeks are general, typical ranges and vary from pregnancy to pregnancy — your provider's schedule and scan dates are what count for you. Only about 1 in 20 babies arrive on the exact due date, so treat every date here as an estimate and confirm your dating with your provider at your first visit.