LMP Calculator Pakistan
Find your LMP date when you only know how far along you are in pregnancy.
Calculate your last menstrual period from current pregnancy weeks (from ultrasound).
How to use this calculator
- Enter weeks pregnant (from ultrasound)
- Add extra days
- See estimated LMP and conception dates
Frequently asked questions
What is LMP?
LMP (Last Menstrual Period) is the first day of your most recent menstrual cycle before pregnancy. Doctors use it to date pregnancies and calculate due dates.
Why find LMP from gestational age?
Useful when ultrasound gave gestational age but you forgot LMP date. Common scenarios: late period awareness, irregular cycles, conception via IVF.
How accurate is reverse calculation?
Accuracy depends on ultrasound dating which is most precise in 1st trimester (within 5-7 days). Later ultrasounds have wider margins (1-2 weeks).
Difference between LMP and conception date?
LMP = day period started. Conception = ~14 days after LMP (ovulation day). Pregnancy is dated from LMP, so 'X weeks pregnant' includes 2 weeks before conception.
What if I had IVF?
For IVF, conception date is exactly known. Calculate LMP as: transfer date - 14 days (for day-3 embryo) or transfer date - 19 days (for day-5/blastocyst).
When is this calculator useful?
When you know weeks pregnant from ultrasound but want to know LMP for: medical records, second opinion, scheduling tests, or just curiosity about conception timing.