Pregnancy Conception Calculator
Last updated: July 2026
Estimate conception date, gestational age and time remaining from an expected due date and reference date.
Estimated conception date
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- Estimated gestational age: —
- Estimated days remaining: —
- Estimated last menstrual period: —
On this page
Quick summary: Estimate conception date, gestational age and time remaining from an expected due date and reference date. Enter the requested values, calculate, review the result, and compare more than one realistic scenario before making a decision.
Read the complete guide
What this calculator estimates
Estimate conception date, gestational age and time remaining from an expected due date and reference date. It is designed for fast planning and comparison in the United States. The output is an estimate, not a binding quote, approval, tax determination, insurance offer, legal conclusion, medical recommendation or professional advice.
How to use it
Enter the requested values using a single consistent time period and currency. Select Calculate, review the headline result and supporting figures, then change one assumption at a time to compare another scenario.
How the calculation works
The estimate subtracts 266 days from the due date for conception and 280 days for the last menstrual period, then compares the reference date.
Important limitations
Pregnancy dating is an estimate and can differ based on cycle length, ovulation, ultrasound and clinical assessment. Consult a qualified healthcare professional.
Frequently asked questions
Is the result exact?
No. It is a planning estimate based on the assumptions entered.
Can I compare different scenarios?
Yes. Change one input at a time so you can see which assumption changes the result.
Does the calculator store my inputs?
The calculation runs in the browser and does not require an account. Avoid entering unnecessary confidential information.