Pregnancy Conception Calculator

Estimate your exact date of conception, identify the 6-day intercourse fertility window, and trace key developmental pregnancy milestones from LMP, ultrasound, or due date.

Scenarios:

Estimation Method

Calculation Inputs

First Day of Last Period (LMP)

Average Cycle Length28 Days

Short (20d)Regular (28d)Long (45d)

Evaluate Age As Of (Reference Date)

Medical Dating Disclaimer

Dates calculated are estimates only, assuming standard follicular development and ovulation lengths. Early ultrasound scans performed in the first trimester remain the clinical gold standard for establishing true gestational age. Always consult your obstetrician for clinical decisions.

Estimated Conception Date

July 1, 2026

Trimester 1 (First Trimester)

Probable Conception Fertile Window

June 26, 2026 – July 1, 2026

Intercourse during these dates likely led to fertilization, factoring in the life cycle of sperm and egg.

Due Date (EDD)

March 24, 2027

Gestational Age

6 Weeks, 0 Days

Days Remaining

238 Days

LMP Clock Start (0%)15% CompletedDelivery (100%)

Developmental Milestones Calendar

Milestone Event	Gestational Age	Target Date	Status
Last Menstrual Period (LMP) Gestational dating clock begins based on reference period cycle.	Start	June 17, 2026	Completed
Estimated Conception Fertilization of the egg by sperm in the fallopian tube.	2 Weeks	July 1, 2026	Completed
Blastocyst Implantation Embryo attaches tightly to the uterine lining.	3.2 Weeks	July 10, 2026	Completed
Neural Tube Closes Early brain and spinal cord form and fuse shut.	4 Weeks	July 15, 2026	Completed
Fetal Heartbeat Heartbeat is detectable on early ultrasound.	6 Weeks	July 29, 2026	Completed
Embryo to Fetus Transition Basic organogenesis complete. Organ systems start working.	10 Weeks	August 26, 2026	Upcoming
Anatomical Screening Window Mid-pregnancy ultrasound to check structural developments.	19 Weeks	October 28, 2026	Upcoming
Fetal Viability Medical threshold of potential survival outside the womb.	24 Weeks	December 2, 2026	Upcoming
Full Term Status Baby's lungs and brain are fully mature for safe birth.	37 Weeks	March 3, 2027	Upcoming
Estimated Due Date (EDD) Estimated completion of 40 weeks gestation.	Due Date	March 24, 2027	Upcoming

Related Calculators

Pregnancy Weight GainTrack recommended week-by-week weight targets Period TrackerForecast upcoming cycles and fertile windows Conception & Gender PlannerForecast future ovulation and fertile scopes

Frequently Asked Questions

How is the conception date calculated from a known due date?▾

The standard human gestation period is defined as 280 days (40 weeks) from the first day of the last menstrual period, which corresponds to exactly 266 days (38 weeks) from conception. The conception date is calculated by subtracting 266 days from your doctor-assigned estimated due date (EDD).

Can an ultrasound scan determine my exact conception date?▾

Yes. An ultrasound scan measures fetal crown-rump length (CRL) or other biometrics to establish gestational age. By inputting the date of the scan and the gestational age in weeks and days recorded during that scan, the calculator back-calculates the reference LMP date, and then estimates ovulation 14 days later to find the conception date.

What is the conception window?▾

The conception window (or fertile window) represents the 6-day span during which intercourse is likely to result in pregnancy. It includes the 5 days before ovulation/conception plus the day of ovulation itself, corresponding to the maximum biological lifespan of healthy sperm inside the reproductive tract (up to 5 days) and the egg's viability after release (about 24 hours).