Pregnancy Due Date Calculator
Estimate your baby's due date based on your last period, conception date, IVF transfer date, or ultrasound.
This tool offers a planning estimate, not a fixed prediction. Roughly 1 in 20 babies arrive right on their due date — most come a bit earlier or later, depending on the individual pregnancy and your provider's own assessment. This isn't medical advice, so always check your due date and care plan with your OB, midwife, or fertility specialist.
Due Date Calculator
Finding out your baby’s expected due date is one of the first questions every expecting parent wants answered. Our pregnancy due date calculator gives you a quick, reliable estimate based on the method that fits your situation best — whether that’s your last period, a known conception date, an IVF transfer date, or an early ultrasound.
Why a Due Date Estimate Matters
A due date isn’t a fixed appointment on the calendar, but it’s still one of the most useful numbers in early pregnancy. It helps you plan prenatal visits, track which trimester you’re in, and get a general sense of when to expect your baby’s arrival.
Most pregnancies last around 40 weeks, counted from the first day of the last menstrual period rather than the actual day of conception. That’s why due dates are always described as estimates — they give you a strong starting point, not a guarantee.
How the Calculator Works
This tool lets you choose the method that matches what you know:
- Last Period: Enter the first day of your last menstrual period, plus your average cycle length. The calculator adds 280 days from that date, adjusting slightly if your cycle runs longer or shorter than the standard 28 days.
- Conception Date: If you know roughly when conception occurred, the calculator adds around 266 days, since conception typically happens about two weeks after the start of a cycle.
- IVF Transfer Date: For IVF pregnancies, the embryo’s exact age at transfer is known, which allows for a more precise estimate. Day 3 transfers add 263 days, while Day 5 (blastocyst) transfers add 261 days.
- Ultrasound Date: If you have an early ultrasound with a recorded gestational age, the calculator can work backward from that measurement to estimate your due date — often useful when period dates are uncertain.
Once you select a method and enter your date, the tool instantly shows your estimated due date, how many weeks along you are, and which trimester you’re currently in.
Understanding Your Results
Along with your due date, the calculator breaks your pregnancy into three trimesters:
- First trimester: Weeks 1–13
- Second trimester: Weeks 14–27
- Third trimester: Weeks 28–40
Seeing this timeline laid out can make it easier to know what’s coming next, from early screenings to third-trimester checkups.
Why Your Due Date Might Shift
It’s common for an estimated due date to change slightly as a pregnancy progresses. A few common reasons include:
- Irregular menstrual cycles
- Uncertainty around ovulation timing
- New information from an early ultrasound
- Carrying twins or multiples, which often shifts delivery earlier
- Additional details reviewed by your healthcare provider
None of this means the original estimate was inaccurate — pregnancy dating naturally gets refined as more information becomes available.
A Few Things to Keep in Mind
Only a small percentage of babies are actually born on their exact due date. Many arrive a week or two before or after, and that’s completely normal for a full-term pregnancy. Think of your due date as the midpoint of a healthy delivery window rather than a firm deadline.
This calculator is designed to give you a clear, quick estimate for planning purposes. For anything specific to your own pregnancy — confirming your due date, reviewing test results, or understanding your individual timeline — it’s always best to check in with your doctor or midwife, who can factor in your complete medical history alongside these calculations.
