Gestational Age Calculator
Free gestational age calculator and pregnancy weeks calculator to estimate how many weeks pregnant you are—shown as weeks + days, total days, trimester, and related EDD.
Pregnancy calculators and fetal growth reference tools for educational use.
Plain-language interpretation
Gestational age traditionally counts from the first day of the last menstrual period, even though conception is usually about two weeks later. Results are complete weeks plus leftover days (for example 12 weeks, 3 days).
Formula and dating standard
- From LMP: gestational days = assessment date − LMP date
- From EDD: imply LMP as EDD − 280 days, then use the same day count
- Display: weeks = floor(days / 7), days = days mod 7
Important assumptions
- LMP method assumes ~28-day cycles when relating to conception.
- Assessment date must not be before the pregnancy start reference.
- Clinical ultrasound dating may supersede LMP arithmetic.
Applicable use
Educational gestational dating across pregnancy when LMP or EDD is known. Not a viability test or fetal monitoring tool.
Worked example
LMP 2024-01-01 and assessment 2024-03-01 → 60 gestational days → 8 weeks, 4 days; EDD 2024-10-07; first trimester.
Limitations
- Not diagnostic.
- No separate /pregnancy-week-calculator URL by design.
- Progress percentage is educational against a 280-day reference.
Frequently asked questions
- How do I know how many weeks pregnant I am?
- This gestational age calculator counts complete weeks and remaining days from the first day of LMP, or from the LMP implied by an estimated due date (EDD − 280 days), to your assessment date.
- Is this the same as a pregnancy week calculator?
- Yes in intent: it answers pregnancy weeks and days. This site keeps a single URL (/gestational-age-calculator) instead of duplicate week-calculator pages.
- What trimester am I in?
- Educational ranges used here: first through 13 weeks 6 days, second through 27 weeks 6 days, third from 28 weeks 0 days. Clinics may use slightly different cutoffs.
Last content review: 2026-07-18. Formula version: pregnancy-dates-v1.