Due date from weeks pregnant
Most due date calculators ask for the first day of your last period. But often the number you actually know is how far along you are — from an appointment, a scan, or an app. This calculator works directly from that: enter your weeks and days pregnant today, and it calculates your due date by adding the time remaining to 40 weeks.
Due date = today + (280 days − days pregnant today)
It also works out the equivalent pregnancy start date, your estimated conception date, your trimester and all your key milestones — so everything lines up with the dating your care team uses.
Quick reference
| Weeks pregnant today | Time to due date |
|---|---|
| 4 weeks | 36 weeks (252 days) |
| 6 weeks | 34 weeks (238 days) |
| 8 weeks | 32 weeks (224 days) |
| 12 weeks | 28 weeks (196 days) |
| 20 weeks | 20 weeks (140 days) |
| 30 weeks | 10 weeks (70 days) |
Each week from 4 to 40 also has its own page — for example 6 weeks pregnant or 12 weeks pregnant — with the due date if you are that far along today.
Prefer your last period?
Switch the calculator to “Last period” to calculate from the first day of your last menstrual period instead. If you have a due date already and want to work backwards, use the Due Date Calculator by Due Date.