Estimate your baby’s due date and see how far along you are — calculate from your last period (the way doctors do), from your due date, or from conception. Then turn it into a live, shareable countdown.
How the due date is worked out
Most pregnancies last about 40 weeks counted from the first day of your last menstrual period (LMP). That is why clinicians date a pregnancy from the LMP rather than from conception, which is usually around two weeks later. This calculator follows Naegele’s rule: estimated due date = first day of your last period + 280 days, adjusted if your cycle is longer or shorter than 28 days.
Your due date is a best estimate, not a deadline — babies set their own schedule. Use the countdown to plan and to share the excitement, and let your doctor or midwife confirm the date with an early scan.
FAQ
How is my due date calculated?
This calculator uses Naegele’s rule — the standard method doctors use. It adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). If you know your conception date instead, it adds 266 days; if you already know your due date, it works backward to date the pregnancy.
How many weeks pregnant am I?
Gestational age is counted from the first day of your last period, not from conception. Enter your last period above and the tool shows how many weeks and days pregnant you are today, plus which trimester you are in.
How accurate is a due date calculator?
It is an estimate. Only about 1 in 20 babies are born on their exact due date — most arrive in the two weeks before or after. An early ultrasound and your doctor or midwife give the most accurate dating.
What if my cycle isn’t 28 days?
Naegele’s rule assumes a 28-day cycle with ovulation on day 14. In “Last period” mode you can set your own cycle length, and the estimated due date is adjusted accordingly.
Can I share my pregnancy countdown?
Yes — after calculating, create a free shareable countdown page with your own link. Friends and family can open it to watch the days tick down to your baby’s arrival. No signup or email required.
Is this medical advice?
No. This tool is for general information and planning only and is not a substitute for professional medical care. Always confirm your due date with your healthcare provider.