How it works
Pick a method, get your full timeline
Enter your LMP, conception date, IVF transfer date, ultrasound measurement, or a known due date. We calculate your EDD, trimester windows, and key milestones.
Calculate
See your estimated due date instantly.
Timeline
View trimester dates and weekly progress.
Milestones
Key prenatal checkups and scan windows.
Methods we support
- LMP (Last Menstrual Period): Adds 280 days to the first day of your LMP.
- Conception date: Adds 266 days from conception.
- IVF transfer: Adjusted calculation based on 3-day/5-day embryo transfer.
- Ultrasound: Uses gestational age from CRL or biometry to anchor your EDD.
- Known due date: Back-calculates your current gestational age and timeline.
Notes
Ultrasound-based dating is often preferred when it differs from LMP. Always use your clinician’s official EDD for care decisions.
Accuracy & limits
What improves accuracy
- Regular cycles or early ultrasound dating
- Consistent method (don’t mix calendars)
- Using clinic-provided measurements
Natural limits
- EDD is an estimate; most births occur ±2 weeks
- Cycle variability and late ovulation shift dates
- Always follow your clinician’s official EDD
FAQ
Which method should I use?▾
If you have an early ultrasound, use that. Otherwise try LMP if your cycles are regular, or conception/IVF if known precisely.
Why do different tools give different dates?▾
Small differences in assumptions (cycle length, luteal phase, ultrasound charts) can shift results. Your provider’s EDD is the source of truth.