Conception Calculator
Estimate when conception occurred
Curious about when you actually conceived? Our conception calculator works backward from your due date to estimate your likely conception window, along with the corresponding start date of your last menstrual period.
This is especially useful if you know your due date from an ultrasound but want a clearer picture of your overall pregnancy timeline.
How This Calculator Works
Since a full-term pregnancy is typically calculated as 280 days (40 weeks) from the last menstrual period, and conception usually occurs around two weeks into the cycle, this calculator subtracts roughly 266 days from your due date to estimate your conception date, and 280 days to estimate your LMP date.
Why Use This Calculator
- Estimate your conception date from a known due date
- Cross-check your pregnancy timeline against your own memory of events
- Useful for prenatal records or curiosity about your pregnancy journey
Frequently Asked Questions
No, it provides an estimate based on average cycle assumptions. The exact day of conception can vary depending on your individual cycle and when ovulation actually occurred.
This can happen if your cycle is shorter or longer than the standard 28 days used in the calculation, or if your due date was later adjusted based on an ultrasound.
Not necessarily. Since sperm can survive for several days, conception can occur a few days after intercourse, once the egg is released during ovulation.
This is an estimate based on standard pregnancy timelines and may not reflect your exact individual cycle.