How is gestational age calculated?

Gestational age is counted from the first day of your last menstrual period (LMP). The number of days since the LMP is shown as weeks plus days, and the estimated due date is the LMP plus 280 days (40 weeks), following Naegele's rule.

How accurate is this tracker?

It uses Naegele's rule, the standard method for an estimated due date, which assumes a regular 28-day cycle. Real cycles vary, and an early dating ultrasound is more accurate. Treat this as an informational estimate, not medical advice — always follow your clinician's dating.

Can I track from my due date instead of my last period?

Yes. Switch the mode to EDD and enter your due date; the tracker works backwards to find the LMP (EDD − 280 days) and then shows your current week, day and trimester.

How many weeks does a full pregnancy last?

A full-term pregnancy is about 40 weeks (280 days) from the LMP. Babies are considered full term from 37 weeks, and anything past the due date is regarded as post-term.

What week does each trimester start?

The first trimester is weeks 0–13, the second is weeks 14–27, and the third runs from week 28 to birth. The tracker labels which trimester your current week falls in.

Why count from the last period and not conception?

The LMP is a date most people can identify, whereas conception happens around two weeks later and is harder to date. Counting from the LMP is the standard clinical convention, so it matches what your provider uses.

Is my pregnancy data kept private?

Yes. The dates you enter are processed entirely in your browser using JavaScript. Nothing is stored, logged or transmitted anywhere.

Pregnancy Week Tracker

Pregnancy week tracker

Find out how many weeks pregnant you are, which trimester you are in and your estimated due date — all from a single date. It is a simple way to follow your progress week by week and see how much of the pregnancy is left.

How it works

You can start from either the last period or the due date, and the tracker derives the other and your current progress:

from LMP:  EDD = LMP + 280 days (Naegele's rule)
from EDD:  LMP = EDD − 280 days
gestational age = days since LMP, shown as weeks + days
trimesters:  1st = weeks 0–13, 2nd = 14–27, 3rd = week 28 onward

It also shows the percentage complete and the days remaining until the due date.

Example

If today is 98 days after the LMP:

Gestational age: 14 weeks 0 days
Trimester: Second
Percentage complete: 98 ÷ 280 ≈ 35%
Days remaining: 280 − 98 = 182 days

Days since LMP	Weeks + days	Trimester
56	8w 0d	First
98	14w 0d	Second
224	32w 0d	Third

This is an informational estimate, not medical advice. Your clinician’s dating scan always takes precedence. Every date is calculated locally in your browser and nothing is uploaded.