A familiar situation
Estimate a possible conception date from pregnancy dating for general calendar orientation only.
How to use this calculator
- Enter known date, due date or lmp, usual cycle length.
- Select Calculate to see the answer and its breakdown.
- Keep a scenario, change an input and compare the results.
Use consistent units and check the assumptions below before applying the result.
How pregnancy conception is calculated
A typical estimate places conception about 266 days before the estimated due date, or near 14 days after a 28-day-cycle LMP. A due date of October 8 corresponds to an estimated conception date around January 15.
Estimated conception≈due date−266 days, or LMP+cycle length−14 days.A due date of October 8 corresponds to an estimated conception date around January 15.
Assumptions & useful context
Calendar estimate; it cannot establish exact fertilization timing.
Health calculations are estimates for education. They cannot diagnose a condition or replace a clinician’s assessment. Individual needs vary, especially during pregnancy, illness and growth.
Frequently asked questions
Can this identify the exact conception day?
No. Ovulation and fertilization timing can vary.
Is this suitable for paternity or legal dating?
No; use appropriate clinical testing and records.