Due date from ovulation
If you tracked OPKs or had a trigger shot, ovulation day may be a better anchor than a fuzzy LMP. This page treats ovulation ≈ fertilization day and adds 266 days. Estimate only — not medical advice.
Uses ovulation ≈ fertilization day, then +266 days.
Enter a date to see an estimate.
What this page does
This is ovulation → EDD only. We do not pitch a bare “ovulation calculator” head-term war against KD70 giants. Cycle-based fertile-window estimates live on the cycle support pages.
Optional LMP-equivalent (EDD − 280) helps apps that still demand a period field.
When to use
Known LH surge / trigger; IUI timing; comparing ovulation-based EDD vs LMP-based EDD.
When not to
Unknown ovulation — use LMP or IVF tools. Full fertile-window prediction without a known ovulation day — see cycle pages.
Assumptions
Browser-only planning arithmetic. Defaults are disclosed on the page. Ultrasound and clinic policy override this tool.
Examples
Ovulation Mar 15, 2026 → EDD Dec 6, 2026.
Same ovulation vs LMP Mar 1 (day-14) → EDDs align when LMP story matches.
Gotchas
Clinic dating after ultrasound can differ from browser math — the clinic wins for medical decisions.
Wrong input dates (retrieval vs transfer, spotting vs true LMP) slide every result.
Estimate only — not medical advice.
How this is calculated
The math stays in your browser. Enter the dates you actually know, read the estimate, and treat clinic ultrasound dating as the authority when it disagrees.
Nothing here is medical advice, a diagnosis, or a substitute for prenatal care.
- Enter the date(s) or numbers this page asks for.
- Check the assumptions under the result and on Methodology.
- Compare with your clinic portal if you have one.
- Use related tools if you only have a different kind of date.
- Confirm medical decisions with your clinician.
EDD = ovulation date + 266; LMP-equivalent ≈ EDD − 280.
Related calculators
LMP path: LMP due date. Workbench: EDD calculator. Conception wording: conception calculator. IVF: IVF due date.
See also: edd calculator, conception calculator, and lmp due date calculator.
FAQ
- How do you calculate due date from ovulation?
- Ovulation date + ~266 days.
- Is this better than LMP?
- When ovulation is well known, often yes for estimates; clinics may still prefer their protocol.
- Do you have a full ovulation calculator?
- We avoid the bare head-term fight; cycle pages estimate timing without that Primary.
- Can I use trigger day?
- Often used as ovulation proxy — uncertainty remains.
- OPK positive timing?
- Surge leads ovulation by ~24h — window uncertainty remains.
- Is this medical advice?
- Estimate only — not medical advice. Confirm dating, testing, and medical decisions with your clinic.