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A May due date means conception in August to early September of the previous year. Find your exact date below.
When Did I Conceive If Due in May: If your due date is in May, you most likely conceived between August 8 and September 7 of the previous year — your due date minus 266 days. Due May 1 → conceived around August 8; due May 15 → around August 22; due May 31 → around September 7. The fertile window spans ±5 days.
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When Did I Conceive If Due in May — If your due date is in May, your likely conception date is your due date minus 266 days (38 weeks) — August 8 – September 7 of the previous year — with a ±5-day fertile window on either side.
Find your exact due date row in the table below for the likely conception date.
Or enter your due date in the calculator above for the exact, leap-year-aware answer.
Treat the result as a window: conception happens at ovulation, up to 5 days after intercourse.
If an ultrasound has revised your due date, use the revised date — it's the more accurate anchor.
Computed as due date − 266 days. The window column adds the ±5-day fertile window around the likely ovulation/conception day:
| Due date | Likely conception | Fertile window | Year |
|---|---|---|---|
| May 1 | Aug 8 | Aug 3 – Aug 13 | previous year |
| May 5 | Aug 12 | Aug 7 – Aug 17 | previous year |
| May 10 | Aug 17 | Aug 12 – Aug 22 | previous year |
| May 15 | Aug 22 | Aug 17 – Aug 27 | previous year |
| May 20 | Aug 27 | Aug 22 – Sep 1 | previous year |
| May 25 | Sep 1 | Aug 27 – Sep 6 | previous year |
| May 31 | Sep 7 | Sep 2 – Sep 12 | previous year |
Dates use a non-leap reference year and can shift by one day when the 266-day span crosses February 29 — the calculator above computes your exact dates.
May babies were conceived in the August–early-September stretch of the previous year. Timeline landmarks for this group: the first trimester ran through the autumn, the 20-week anatomy scan landed around Christmas–New Year, and the third trimester coincided with spring. One planning note — a May due date usually means the final weeks of pregnancy overlap tax season and, for teachers and students, the end of the school year, which is why May is a popular 'planned' due month in education households.
Medical Disclaimer
This calculator provides estimates only. Always consult with your healthcare provider for accurate pregnancy dating and medical advice.
Conception Date: The estimated date when fertilization occurred, typically 11-21 days after the first day of your last menstrual period.
Conception Range: A four-day timeframe during which fertilization most probably occurred, taking into consideration that sperm can remain viable in the reproductive tract for 3-5 days.
Gestational Age: The age of the pregnancy calculated from the first day of the last menstrual period, not the actual conception date.