Let’s Calculate Your
Due Date
Find out how far along you are, when your baby arrives, and what's happening week by week — in seconds. Every great pregnancy journey starts with one date. Let’s find yours.
Pregnancy Calculator
Enter the first day of your last menstrual period (LMP) to calculate your due date, current week, and full pregnancy timeline.
This calculator provides estimates based on a standard 40-week pregnancy from LMP.
Results are for informational purposes only — always consult your healthcare provider for personalized guidance.
Understanding Your
Due Date Calculator Results
Due Date
Your due date is calculated by adding 280 days — exactly 40 weeks — to the first day of your last menstrual period. This method is called Naegele's Rule, and it's the same formula your OB or midwife uses. It assumes a 28-day cycle with ovulation around day 14, so if your cycle runs longer or shorter than average, your provider may fine-tune the date after your first ultrasound. Either way, it's your north star for the months ahead.
Current Week & Trimester
Pregnancy is divided into three trimesters, each with its own rhythm of development, symptoms, and milestones. Knowing exactly which week you're in helps you understand what's happening with your baby right now — and what's coming next. Your current week is counted from your LMP, which is why Week 1 starts before conception even occurs. It sounds strange, but it means your provider can start tracking your pregnancy from a date you actually know.
Weeks Remaining
Here's something worth knowing: the weeks don't always feel equal. The first trimester can feel endless when you're exhausted and queasy. The second trimester tends to fly. The third slows back down as you near the finish line. Use the weeks-remaining number as a gentle compass, not a countdown clock. There's no rushing this particular journey — and most of the time, you wouldn't want to.
Baby Size
The fruit and vegetable comparisons are a beloved pregnancy tradition for good reason — they make something invisible feel real and tangible. When you can picture a blueberry or an avocado, the abstract idea of a growing baby suddenly has shape and weight and personality. Keep in mind that these are averages. Babies vary in size just like people do, and a baby measuring slightly larger or smaller than the comparison is almost always perfectly healthy.
What Happens Each Trimester
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This is where it all begins. In just the first eight weeks, your baby develops from a cluster of cells into a recognizable little human — complete with a heartbeat, tiny limbs, and facial features that are already uniquely their own. Meanwhile, your body is working harder than it ever has, even if you have nothing to show for it yet.
The fatigue, the nausea, the heightened emotions — all of it is evidence of something extraordinary happening beneath the surface. Many people keep their pregnancy private during this trimester, which can make it feel both magical and quietly lonely at the same time. Both feelings are valid. So is eating crackers in bed at 10am.
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For most people, the second trimester arrives like a deep breath after a long climb. The nausea tends to lift. Energy returns. The bump becomes undeniable, and strangers start to notice. Somewhere around weeks 18 to 22, you may feel your baby move for the first time — a flutter, a nudge, an unmistakable hello from the inside.
This is also when your anatomy scan happens, offering a detailed look at your baby's development and, if you want to know, a peek at their sex. The second trimester is when pregnancy starts to feel less like something happening to you and more like something you're doing together.
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You're in the final chapter now. Your baby is gaining weight, practicing breathing, and running out of room — which you are probably very aware of. Sleep gets harder. The back aches. You might find yourself reorganizing the nursery at midnight for the third time. That's nesting, and it's completely normal.
This trimester is also when the anticipation builds to something almost unbearable in the best possible way. Every appointment, every kick, every contraction that turns out to be nothing — it's all leading somewhere. Somewhere wonderful. You're almost there.
Want to Track Every Week?
There's a Calendar for That.
The calculator above tells you where you are. The Pregnancy Calendar helps you live every moment of it.
For over 30 years, expectant parents have turned to The Pregnancy Calendar to follow their baby's development week by week, stay on top of prenatal appointments, and capture the small, fleeting details they never want to forget — the first kick, the heartbeat they heard at 10 weeks, the name they finally agreed on at 3am.
It's not an app. It's not a generic journal. It's a beautifully designed, pediatrician- and OB-GYN-approved guide that unfolds alongside your pregnancy in real time — because some journeys deserve to be held in your hands, not just tracked on a screen.
Over 2 million families have used it. Their babies are in college now. They still have the calendar.
Inside every copy:
Week-by-week fetal development from Week 1 through Week 42
Space to record prenatal appointments, questions, weight, and measurements
Milestone pages for first kicks, cravings, nursery prep, and baby names
Room to attach ultrasound photos and journal your memories
96 stickers to mark the moments that matter most
Lighthearted extras — a crossword, a word search, fill-in-the-blanks — for the long waiting room stretches
Whether you're buying it for yourself or giving it as a baby shower gift, it's the kind of keepsake that ends up in the baby box — and gets pulled out years later when your child wants to know the story of before they arrived.
Frequently asked questions about the Due Date Calculator
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Don't worry — you're not alone! Many people don't track their cycle closely, or have irregular periods that make pinpointing the date tricky. In that case, your healthcare provider will use an early ultrasound to estimate your due date based on your baby's size and development. If you have a rough idea of when your last period started, go ahead and use that — your doctor will confirm or adjust your due date at your first prenatal appointment.
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Yes, and that's completely normal. An early ultrasound (typically done in the first trimester) is actually the most accurate way to date a pregnancy. If the measurements show your baby is measuring ahead or behind your LMP-based estimate by more than a few days, your provider may adjust your due date accordingly. Think of your due date less as a deadline and more as a target window — your baby will arrive when they're ready.
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Pregnancy is counted from the first day of your last menstrual period — not from conception. This means that when you're said to be "4 weeks pregnant," your baby may only be about 2 weeks old. It's a little counterintuitive, but it's the standard used by healthcare providers worldwide because LMP is usually easier to pinpoint than the exact date of conception. So those first couple of weeks? You were technically pregnant before you were pregnant. Welcome to the wonderfully strange world of expecting.
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Only about 5% of babies arrive on their actual due date — so try not to circle it in red marker and stare at it for 9 months. Due dates are best thought of as the midpoint of a natural arrival window. Most babies are born somewhere between 38 and 42 weeks, and a full-term pregnancy is considered anywhere from 39 to 40 weeks and 6 days. Your body and your baby will take the lead on timing. The date is a guide, not a guarantee.
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Gestational age is what your doctor uses — it counts from the first day of your LMP and is the number you'll see on ultrasound reports and in pregnancy apps. Fetal age (sometimes called embryonic age) counts from the moment of fertilization, which is typically about two weeks after your LMP. So if your provider says you're 10 weeks along, your baby's fetal age is closer to 8 weeks. The calculator above uses gestational age, which is the universal standard for tracking pregnancy milestones and due dates.