Your estimated due date (EDD) is the day around which your baby is most likely to arrive — though only about 1 in 20 babies actually arrives on it. Here's how it's worked out.
The 280-day rule
Pregnancy is dated as 280 days (40 weeks) from the first day of your last menstrual period (LMP). This is known as Naegele's rule. Because ovulation and conception typically happen about two weeks after your period starts, your baby is actually around 38 weeks old at birth — but the count starts from the LMP for consistency.
If you know your conception date
If you know when you conceived (for example from ovulation tracking), your due date is roughly 266 days from conception. Journey280 converts a conception date to an LMP automatically (LMP ≈ conception − 14 days).
Refining with a positive test or scan
If you only have a positive pregnancy test, the date and type of test (urine or blood) can be used to estimate a conception window. The most accurate dating, however, comes from an early dating scan, which measures the baby and can adjust your due date.
Why "day X of 280" matters
Thinking of pregnancy as a 280-day countdown makes each week feel like a milestone. Journey280 shows exactly which day you're on, how many days remain, and your baby's size for that week.
Your due date is an estimate — your care team will confirm it with a scan.