Pregnancy Calculator
Estimated due date
2026-10-08
Pregnancy Due Date Calculator
Day of the week
Thursday
Dating LMP
2026-01-01
Estimated conception date
2026-01-15
Dating method used
Last menstrual period, 28-day cycle
Gestational age today
21w 4d
Weeks pregnant
21
Extra days
4
Gestational age in days
151
Trimester
2
Days until the due date
129
Pregnancy complete
53.93 %
Reaches 24 0/7 weeks
2026-06-18
Reaches 37 0/7 weeks (early term)
2026-09-17
Reaches 39 0/7 weeks (full term)
2026-10-01
Reaches 41 0/7 weeks (late term)
2026-10-15
Reaches 42 0/7 weeks (postterm)
2026-10-22
Worked out from ACOG Committee Opinion No. 700: Methods for Estimating the Due Date and 2 other sources.
At 21 4/7 weeks this pregnancy is preterm (before 37 0/7 weeks).
An estimate from calendar arithmetic, not a clinical assessment. Only about 4% of births occur on the estimated due date; ultrasound dating by a clinician supersedes menstrual dating when they disagree.
How this is worked out
5 steps
- Ovulation is one luteal phase before the next period would start: 28 - 14 = day 14 of the cycle, so 2026-01-15.
- Estimated due date = ovulation + 266 days.
- With a 28-day cycle this is exactly Naegele's rule: LMP + 280 days.
- Estimated due date = 2026-10-08 (Thursday).
- On 2026-06-01 the pregnancy is 151 days from the dating LMP, i.e. 21w 4d.
Dating milestonestable
| label | gestationalAge | date |
|---|---|---|
| End of first trimester | 13 6/7 weeks | 2026-04-08 |
| Start of second trimester | 14 0/7 weeks | 2026-04-09 |
| Anatomy scan window opens | 18 0/7 weeks | 2026-05-07 |
| Limit of periviability | 24 0/7 weeks | 2026-06-18 |
| Start of third trimester | 28 0/7 weeks | 2026-07-16 |
| Early term begins | 37 0/7 weeks | 2026-09-17 |
| Full term begins | 39 0/7 weeks | 2026-10-01 |
| Estimated due date | 40 0/7 weeks | 2026-10-08 |
| Late term begins | 41 0/7 weeks | 2026-10-15 |
| Postterm begins | 42 0/7 weeks | 2026-10-22 |
Results are general information, not financial, tax, legal, medical or engineering advice.