Pregnancy Calculator
Estimate due dates, gestational weeks and trimester milestones using a period date, conception, IVF transfer or clinician-set date.
Private by design
Your inputs stay on your device and are not sent to our servers. Optional usage analytics does not receive your files or tool inputs.
Your dates
Assumptions and clinical sources
LMP: 280 days plus cycle length minus 28. Known conception: 266 days. IVF: transfer date plus 266 days minus embryo age. A clinician-set due date is used unchanged. Gestational weeks are counted from the equivalent LMP, not conception. This is a date estimate, not a pregnancy test. Ultrasound and your care team's dating take priority.
NHS: Pregnancy due date calculator ↗ACOG: Methods for estimating the due date ↗Calculated locally. Inputs are not uploaded or saved by this tool.
Your next chapter, mapped out
Choose a dating method and date to see your estimated timeline.
How to use Pregnancy Calculator
- Choose last period, known conception, IVF transfer or a clinician-set due date.
- Enter dates and adjust the cycle length or embryo age where applicable.
- Review weeks, trimester and calendar milestones. Save a summary or calendar.
What are the limits of Pregnancy Calculator?
Calendar estimates do not confirm pregnancy or predict the exact birth date. Irregular cycles reduce LMP accuracy. Your clinician’s established dating takes priority. Inputs stay in browser memory.