Weeks Pregnant Calculator

Pregnancy is counted in weeks from the first day of the Last Menstrual Period (LMP). Full term is 40 weeks

The calculator uses the standard published formula for weeks pregnant. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, watts. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Weeks = (Today − LMP) / 7. Each step in the calculation is shown so you can verify the result manually.