Pregnancy Conception Calculator

Use it for simple educational checks, trend tracking, or planning tasks like these: Estimate conception timing from an expected due date. Find a possible conception window instead of one exact day. It can help you understand a number, but it cannot explain your whole health situation.

Enter the estimated due date you were given by a clinician, ultrasound report, or earlier due-date calculation. This calculator works backward from that date only. If the due date changed after ultrasound, IVF dating, or clinician review, use the updated date instead of an older calendar estimate.

In plain language: The calculator estimates conception as due date minus 266 days, shows a possible window about five days before and after that estimate, and estimates LMP as due date minus 280 days. Read the result together with the notes on the page, because health and fitness numbers often need personal context.

Read the center date as a backward estimate from the due date, not proof of the exact day conception happened. The possible window is more honest than a single day because ovulation, fertilization, sperm survival, ultrasound dating, and due-date assumptions can all shift the real timing.

A common due-date estimate counts about 280 days from the first day of the last menstrual period. Conception or ovulation is often estimated about 14 days after that in a 28-day cycle, so due date minus 266 days is a backward estimate of conception timing.

No. The center date and window are estimates. Ovulation can shift, sperm can survive for several days, fertilization timing can vary, and the due date itself may have been estimated. Use the result for planning context, not proof.

No. A due-date calculator cannot prove biological parentage or separate close intercourse dates. If parentage matters, use appropriate medical or legal testing and professional guidance instead of calendar math.

Use the official due date from your clinician if one has been assigned. IVF and early ultrasound dating can use different assumptions than simple LMP calendar math, so ask your care team how that date should be interpreted.

No. This page provides an educational estimate only. Talk with a qualified health professional before making medical, pregnancy, nutrition, medication, or safety decisions. Use the calculator as a learning tool, then ask a qualified professional about decisions that affect care, pregnancy, medication, nutrition, or safety.

Check the units, date, and personal details before reading the answer. For example, pounds and kilograms, inches and centimeters, or a wrong activity level can change the result quickly. If the number feels surprising, rerun it slowly and compare it with the examples.

No. The calculator runs in your browser tab. Recent answers stay only on the page while you use it, and they are not sent to a server.