- Mon to Sat: 11am - 2pm, 6:30pm - 9pm
- +91 9967738303
Estimate your baby’s arrival and see exactly how far along you are today.
A due date is worked out from the first day of your last period, not from the day you conceived, which is why a full pregnancy is counted as 40 weeks rather than 38. This tool takes whichever date you actually know, whether that is your last period, your conception or IUI date, a due date your doctor has already given you, a dating scan result or an IVF transfer date, and works the rest out from there. It also shows how far along you are today and the milestones ahead. It is an educational guide, not a substitute for a scan. If your cycles are irregular or you are unsure of your dates, an early ultrasound with Dr. Grishma Ranjangaonkar will settle them properly.
Choose a method above and enter the date you know. You will get your due date, how far along you are today, and the milestones ahead.
Pregnancy is divided into three trimesters. Here is roughly what each one covers, counted in weeks from the first day of your last period.
Weeks 1 to 13. Every major organ forms in this window. Morning sickness and tiredness peak, and the dating scan usually happens between 11 and 14 weeks.
Weeks 14 to 27. Most women feel considerably better. The anomaly scan falls between 18 and 22 weeks, and first movements are usually felt around 18 to 22 weeks.
Weeks 28 to 40. The baby gains most of its weight. Visits become fortnightly, then weekly, with growth scans and position checks.
Weeks 37 to 42. Anything from 39 to 41 weeks is considered full term. Only about one baby in twenty arrives on the estimated date itself.
The single date matters less than the range around it. Here is how to use what the calculator gives you.
Around four per cent of babies arrive on their estimated due date. The useful information is the range: most healthy births happen between 37 and 42 weeks, so plan for a month rather than a day and you will spare yourself a lot of anxiety.
If your dating scan gives a different date to this calculator, the scan wins, and by a wide margin. Early fetal measurements are accurate to within about five days, whereas a calculation assumes you ovulated on day 14 of a textbook cycle, which most women do not.
The dates for the anomaly scan, the viability mark and the start of the third trimester are the ones worth putting in a calendar. They are when tests are scheduled and when leave and travel decisions usually need making.
Your due date is not just a countdown. It sets the timing of nearly every check in your pregnancy.
This method assumes a regular cycle and a known last period. In these situations the number it gives should be treated with real caution.
The calculation assumes you ovulated 14 days before your next period was due. If your cycles vary widely, ovulation could have happened a week or more later than assumed, which pushes the real due date back by the same amount. A scan is the only way to know.
If you cannot remember the date bleeding started, or you had spotting you mistook for a period, the starting point is wrong and everything after it shifts. Book an early scan rather than guessing.
These are the one case where the dates are more precise than usual, because the conception date is known exactly. Use the IVF transfer tab and the embryo age rather than the last-period method, which will give a slightly different answer.
Twins are rarely allowed to reach 40 weeks. Most are delivered between 36 and 38 weeks, and triplets earlier still, so treat the standard due date as a ceiling rather than a target and follow the plan your obstetrician sets.
An early ultrasound gives you a due date accurate to within a few days, confirms the pregnancy is in the right place, and checks the heartbeat. Dr. Grishma Ranjangaonkar has over 15 years of experience in obstetrics and high-risk pregnancy care.
The standard method is Naegele’s rule: add 280 days, or 40 weeks, to the first day of your last menstrual period. Because that counts from your period rather than from conception, the first two weeks of a “pregnancy” happen before you are actually pregnant. If your cycle is not 28 days, this tool adjusts for the difference, since a longer cycle means later ovulation and therefore a later due date.
Roughly four in every hundred babies are born on their estimated due date. About two thirds arrive within a week either side of it, and the large majority between 37 and 42 weeks. A first-trimester dating scan narrows the estimate to within about five days, which is why it is used in preference to any calculation.
If you have had a dating scan, use the ultrasound tab and enter what the report said. If you conceived through IVF, use the transfer date, which is the most precise of all. If you know your ovulation or IUI date, use conception. Otherwise use your last period, and adjust the cycle length to your own.
Because the calculator assumes textbook ovulation on day 14 and your body may not have obliged. Late ovulation is the usual explanation, and it is entirely normal. If the scan and the calculation differ by more than about a week in the first trimester, the scan date is the one your care will be planned around.
Not reliably. With irregular cycles the date of ovulation can vary by two weeks or more between cycles, so the assumption the calculation rests on does not hold. An early scan is the sensible route, and it is worth asking about the irregularity itself, since thyroid problems and PCOS often sit behind it.
Gestational age is counted from the first day of your last period and is what every clinic, scan report and pregnancy app uses. Fetal age, sometimes called conceptional age, counts from fertilisation and is about two weeks less. When someone says “12 weeks pregnant” they mean gestational age.
Typically a dating scan at 11 to 14 weeks, an anomaly scan at 18 to 22 weeks, and growth scans in the third trimester as needed. High-risk pregnancies are monitored more closely. The calculator lists these windows against your own dates once you enter them.
Usually, but it is monitored. Beyond 41 weeks the placenta becomes less efficient and the risk of complications rises gradually, so most obstetricians will discuss induction between 41 and 42 weeks. Going a few days over is very common and not in itself a cause for worry.
