Pregnancy
Pregnancy Due Date Calculator
PanaKit's pregnancy due date calculator estimates your due date five different ways, from your last period, conception date, IVF transfer, current week pregnant, or working backward from a due date you already have. Pick whichever date you know. Runs instantly in your browser, and nothing you enter is stored or sent anywhere. For a full IVF and frozen embryo transfer (FET) walkthrough, see how to calculate your FET due date.
Estimate Your Due Date
Naegele's rule with optional cycle-length adjustment.
Enter the fields for your selected mode. Results stay on this device.
Choose a mode and enter dates to see your estimate.
How it's calculated
The standard method, Naegele's rule, adds 280 days to the first day of your last menstrual period, assuming an average 28 day cycle. Conception based estimates add 266 days instead, since conception typically happens about 14 days into that cycle. IVF transfers use the transfer date plus a fixed offset based on embryo age at transfer. Every method here is an estimate, since actual pregnancy length varies naturally from person to person. An early ultrasound is generally considered the most accurate single method when available.
Frequently asked questions
Yes. Enter how many weeks (and days) pregnant you are right now, and the calculator works out your estimated due date and conception date from that, without needing your last period date. This is useful if your doctor already told you your current week.
Yes. Enter your due date and the calculator estimates your conception date (about 266 days earlier) and your last menstrual period date (about 280 days earlier), working in reverse from the date you already know.
Yes, the LMP based calculation follows Naegele's rule, the standard method used in clinical practice, adding 280 days to the first day of your last period. An early ultrasound, when available, is generally considered the most accurate method overall, since it measures the fetus directly.
Less accurate than for a regular cycle, since the standard formula assumes an average 28 day cycle. If your cycles vary significantly, an ultrasound based estimate or the conception date and current week modes on this calculator, which don't rely on cycle regularity, will generally be more reliable than the LMP based estimate alone.