About this tool
Free Pregnancy Calculator
Wondering how far along you may be or when your baby could be due? This free online Pregnancy Calculator provides an immediate estimate of your due date, current pregnancy week and day, approximate month, trimester, and upcoming milestones. Calculate from the first day of your last menstrual period (LMP), a known or estimated conception date, or gestational age already recorded on an ultrasound report. The pregnancy due date calculator by last period follows the standard pregnancy-dating convention: an estimated 280 days, or 40 weeks, from the first day of the LMP. If your average cycle differs from 28 days, the calculator adjusts the estimate by the difference in cycle length. Gestational age begins before conception under this convention, which is why it is usually about two weeks greater than fetal age. For an LMP estimate, enter the first day of your last period and usual cycle length. This pregnancy calculator by last menstrual period is most useful when that date is known and cycles are reasonably regular. Irregular cycles, recent hormonal contraception, breastfeeding, or uncertainty about the date can make an LMP result less reliable. If conception timing is reasonably known, choose Conception and enter that date. A pregnancy calculator based on conception date adds approximately 266 days, or 38 weeks, to estimate the due date. Conception may still be an estimate unless timing was documented through assisted reproduction or closely monitored ovulation. The Ultrasound option is not a scan interpreter. It works as a due date calculator by ultrasound only when you enter the scan date and the gestational weeks and days already reported by a qualified clinician. The tool projects the remaining time to 40 weeks. Early ultrasound is commonly considered when menstrual dates are uncertain, but your official obstetric due date should be established and documented by your healthcare professional. If you are asking “how many weeks pregnant am I?”, the calculator displays estimated gestational age in completed weeks and additional days. Pregnancy is tracked in weeks because this gives healthcare teams a consistent way to schedule care and describe development. This pregnancy calculator with trimester breakdown uses common clinical boundaries: the first trimester runs through 13 weeks and 6 days, the second from 14 weeks through 27 weeks and 6 days, and the third begins at 28 weeks. Months are less exact because calendar months have different lengths. The displayed pregnancy month is therefore approximate; for appointments and medical decisions, rely on gestational weeks and the dating recorded by your clinician. The timeline includes the estimated start of the second trimester, start of the third trimester, 37-week point, and due date. These are planning references rather than predictions of exactly when labor will begin. Pregnancy commonly lasts between 37 and 42 weeks from the first day of the last period, and only about one in twenty babies is born on the estimated due date. Use this baby due date calculator as a free planning tool, not as a pregnancy test or diagnosis. It cannot assess fetal growth, pregnancy viability, complications, or symptoms. Confirm dating and care decisions with a doctor, midwife, or other qualified healthcare professional. Seek urgent medical care for severe pain, heavy bleeding, fainting, breathing difficulty, or any symptom that concerns you.
Looking for more focused planning utilities? Browse the Calculators collection. Pregnancy dates from this tool are estimates and should be confirmed with a qualified healthcare professional.
Step by step
How to use Pregnancy Calculator
- 1
Choose Last period, Conception, or Ultrasound according to the dating information you have.
- 2
For LMP, enter the first day of your last menstrual period and your average cycle length.
- 3
For conception, enter the known or best-estimated conception date.
- 4
For ultrasound, enter the scan date plus the gestational weeks and days stated on the clinician's report.
- 5
Review the estimated due date, gestational age, trimester, approximate month, progress, and milestones.
- 6
Copy the summary if useful, then confirm the estimate with your doctor or midwife.
Highlights
Pregnancy Calculator features
Pregnancy due date estimate by last menstrual period
Cycle-length adjustment for LMP dating
Conception-date due date calculation
Ultrasound report date and gestational-age projection
Current pregnancy week and day estimate
Trimester and approximate month breakdown
Second trimester, third trimester, 37-week, and due-date milestones
Clear medical-estimate notice and private browser calculation
Questions
Pregnancy Calculator FAQ
How accurate is this pregnancy due date calculator?+
It provides an estimate using standard dating conventions. LMP accuracy depends on knowing the date and having reasonably regular cycles. A clinician may revise the estimate after reviewing your history and an appropriate ultrasound.
How many weeks pregnant am I?+
Select a dating method and enter the requested details. The tool estimates completed gestational weeks and additional days as of today. Clinical records should be used for official pregnancy dating.
How does the pregnancy calculator by last menstrual period work?+
It starts with the first day of the LMP and uses an estimated 280-day pregnancy, adjusted by the difference between your entered cycle length and a 28-day cycle.
Can I use this calculator if my periods are irregular?+
You can, but an LMP result may be less reliable. Discuss uncertain dates with a healthcare professional; an appropriately timed ultrasound may help establish clinical dating.
Can I calculate a due date from conception?+
Yes. The conception method adds about 266 days to the date entered. Unless conception was documented, that date may itself be an estimate.
How do I use the ultrasound option?+
Enter the ultrasound date and the gestational weeks and days already stated by a qualified clinician. The calculator does not analyze an image or determine gestational age on its own.
What is the difference between gestational age and fetal age?+
Gestational age is conventionally counted from the first day of the LMP. Fetal age is counted from conception and is usually about two weeks less, although ovulation timing varies.
Which weeks belong to each trimester?+
This tool uses first trimester through 13 weeks 6 days, second trimester from 14 weeks through 27 weeks 6 days, and third trimester beginning at 28 weeks.
Will my baby arrive exactly on the estimated due date?+
Probably not. Only about one in twenty babies is born on the estimated date, and many births occur within the broader term window around it.
Can this calculator confirm pregnancy or replace medical advice?+
No. It cannot confirm pregnancy, evaluate symptoms, assess fetal health, or replace prenatal care. Use a pregnancy test and consult a qualified healthcare professional.