Pregnancy Conception Calculator
Estimated conception date.
Private — runs in your browser Instant results
Estimated conception date
January 15, 2026
This estimate is not evidence of conception timing or parentage.
Introduction
Estimate a possible conception date from either an estimated due date or a last menstrual period. This is only a calendar estimate and cannot establish when conception occurred.
What is Pregnancy Conception Calculator?
This tool provides a calendar estimate only. From an estimated due date, it counts back 266 days. From LMP, it estimates a possible ovulation date based on the usual cycle length. Neither method can prove the date of conception or determine parentage.
Definition: Pregnancy Conception Calculator estimates a possible conception date from an estimated due date or a last menstrual period.
Calculation steps
- Configure the inputs shown in the Pregnancy Conception Calculator form above.
- The tool applies the method described by its inputs and result labels.
- Review the result and the assumptions used to produce it.
- Use the related tools below when you need a different pregnancy task.
Worked example
Example: estimate conception from an estimated due date
Inputs: Estimated due date = 8 October 2026
- Count back 266 days from the estimated due date.
- Display the resulting calendar date as an estimate.
- Keep in mind that conception timing cannot be determined exactly by this calculation.
The result is a possible conception date, not proof of conception timing or parentage.
Use cases
- Understanding how estimated due dates and conception-date estimates relate
- Keeping a personal calendar estimate
- Preparing a question for a prenatal-care appointment
Advantages
- Browser-based processing — entered values and selected files are not sent to our servers
- No account required
- Instant results with a clean, readable interface
Limitations
- Ovulation and fertilisation do not occur on the same predictable day for everyone.
- The result cannot establish parentage, sexual timing, or a medical fact.
- Assisted reproduction and clinical dating need individual medical documentation.
Frequently asked questions
- How is conception estimated from a due date?
- The calculator counts back 266 days from the estimated due date. This is a standard calendar approximation, not an exact conception record.
- Can this tell me exactly when conception happened?
- No. It cannot determine an exact date because ovulation and fertilisation timing vary.
- Can this be used for paternity questions?
- No. A calendar estimate cannot establish parentage. Seek appropriate professional guidance for questions that require evidence.
- Is the Pregnancy Conception Calculator free to use?
- Yes. Pregnancy Conception Calculator on The Daily Tools is completely free, requires no account, and runs entirely in your browser.
- Does The Daily Tools store my inputs?
- No. Your numbers and text never leave your device. The Daily Tools has no backend database for calculator inputs.
- Who should use the Pregnancy Conception Calculator?
- Anyone who needs a clear health and fitness calculation and wants to check the assumptions used.
- How accurate is the Pregnancy Conception Calculator?
- Results are computed locally using established methods for pregnancy. Treat outputs as estimates, not professional advice.
- Can I use the Pregnancy Conception Calculator on mobile?
- Yes. The Daily Tools is fully responsive and works on phones, tablets, and desktops.
Sources & references
Key points
- Pregnancy Conception Calculator is a free, browser-based calculator for estimated conception date.
- Estimated conception date.
- Private, browser-only processing
- Private, browser-based processing