How far along am I? Find out your pregnancy week and day, your trimester and your estimated due date — starting from your last period, due date or conception date.
The date from your due date calculator, first scan, or provider.
Roughly your ovulation date — pregnancy dating counts this as about 2 weeks along.
When someone asks "how far along am I?", the answer is a number called your gestational age — and it's measured in a way that surprises almost everyone the first time they hear it. Pregnancy is dated not from the day you conceived, but from the first day of your last menstrual period (LMP). That convention exists for a simple, practical reason: most people can remember when their last period started, while the exact moment of conception usually can't be pinned down.
The quirk of this system is that weeks 1 and 2 of your pregnancy happen before you're actually pregnant. During that first stretch your body is preparing to release an egg. Ovulation and conception typically arrive around the end of week 2, so by the time a home test turns positive you're often already being counted as 4 or 5 weeks along. It feels like a head start, but it's just where the calendar begins.
From that starting line, a full-term pregnancy runs about 40 weeks, or 280 days. Your estimated due date is simply your LMP plus 280 days — the classic calculation known as Naegele's rule. This calculator does that math for you, then works out how many of those weeks and days you've already traveled. It expresses your progress the way your provider will: as completed weeks plus extra days, so "8 weeks and 3 days" means you've finished 8 full weeks and you're 3 days into your ninth.
Everything here runs entirely in your browser. Nothing you type is stored, sent or shared — the calculation happens on your own device and disappears when you close the page.
Pregnancy is traditionally divided into three trimesters, each with its own rhythm and milestones. The boundaries below follow the common convention used by most providers and by this calculator. Remember that these are guideposts, not hard biological switches — every pregnancy moves at its own pace.
| Trimester | Weeks | What's happening |
|---|---|---|
| First trimester | 0w 0d – 13w 6d | Major organs and body systems form. Early symptoms like nausea and fatigue are common. The first dating scan usually happens here. |
| Second trimester | 14w 0d – 27w 6d | Often the most comfortable stretch. Many people feel first movements, and the anatomy scan around 18–22 weeks checks the baby's development. |
| Third trimester | 28w 0d and beyond | The baby gains weight and matures the lungs and brain for life outside. Prenatal visits grow more frequent as your due date nears. |
Dating from your last period rests on one big assumption: that you ovulated around day 14 of a roughly 28-day cycle. For many people that holds up well. But if your cycles run long, short or unpredictable, ovulation may land earlier or later — and your true gestational age shifts along with it. That's why this calculator lets you enter your cycle length, nudging the dating a little later for longer cycles and earlier for shorter ones.
Even so, calendar math has limits. An early ultrasound measures the embryo or fetus directly and is the most accurate way to date a pregnancy, especially when performed before 14 weeks. If your scan-based due date differs from your LMP-based estimate by more than a few days, your provider will usually adopt the ultrasound date — and every week number from then on follows from it. This matters most for people with irregular cycles, uncertain period dates, or conception soon after stopping hormonal birth control.
The takeaway isn't that calendar dating is wrong — it's a genuinely useful starting point. It's that ultrasound is more precise, and when the two disagree, the scan wins. Treat the numbers here as a friendly first estimate to be confirmed and, if needed, gently corrected at your appointments.
The 280-day, 40-week figure is an average, not a deadline. It comes from adding 280 days to the first day of your last period, which works out to roughly 38 weeks from conception. A due date is best understood as the center of a range rather than a scheduled event. Full term is defined as 39 weeks 0 days through 40 weeks 6 days, and healthy babies routinely arrive across a wider window than that.
Here's the reality that catches many first-time parents off guard: only about 1 in 20 babies is born on the estimated due date itself. The large majority arrive in the two weeks on either side of it. So while it's natural to fixate on that single square on the calendar, it's healthier to think in terms of "sometime around" your due date. Your body and your baby set the true timeline.
Providers watch the calendar mainly at the edges. Birth before 37 weeks is preterm, and pregnancy that continues past 42 weeks is post-term — both are situations where extra monitoring or planning may come into play. In between lies a broad, normal zone where the exact day is simply part of the surprise.
A week calculator is a wonderful way to picture where you are and what's coming next, but it isn't a substitute for prenatal care. Your midwife or doctor will confirm your dates, usually with an early scan, and use that confirmed gestational age to schedule tests, screenings and milestones throughout your pregnancy. If the number here differs from what your provider tells you, trust your provider — they have information this tool doesn't.
It's also worth bringing a few things to your first appointment: the first day of your last period if you know it, a rough sense of your usual cycle length, and any ovulation or conception dates you tracked. Those details help your provider date the pregnancy as accurately as possible. And if anything about your symptoms worries you at any stage, don't wait for a scheduled visit — reach out. This calculator can inform your questions, but your care team gives the answers.
Your "how far along" number is your gestational age, counted from the first day of your last menstrual period (LMP) — not from conception. To find it, subtract your LMP from today's date and express the result in weeks and days. For example, if it has been 56 days since your last period, you are 8 weeks and 0 days along. If you don't know your LMP, you can work backward from your due date or your conception date instead, which is exactly what this calculator does.
By medical convention, pregnancy is dated from the first day of your last period because that is a date most people can identify, while the exact moment of conception usually can't be pinned down. Ovulation and conception typically happen about two weeks after your period starts, so during weeks 1 and 2 you are not actually pregnant yet. That's why a pregnancy described as "40 weeks" is only about 38 weeks from conception.
A full-term pregnancy is counted as about 40 weeks, or 280 days, from the first day of your last period. Babies born between 39 weeks 0 days and 40 weeks 6 days are considered full term. Birth any time from 37 weeks is called early term, and pregnancy is considered post-term after 42 weeks. Only around 1 in 20 babies actually arrives on the estimated due date itself.
A due date from your last period is a solid estimate when your cycles are regular and close to 28 days, but it assumes you ovulated on day 14. If your cycles are longer, shorter or irregular, that assumption can be off by several days. An early ultrasound — ideally before 14 weeks — measures the baby directly and is the most accurate way to date a pregnancy, which is why your provider may adjust your dates after your first scan.
Yes. If your cycles are longer than 28 days, you likely ovulate later, so for the same last-period date you are actually a little less far along than standard math suggests. This calculator lets you enter your cycle length and shifts the dating accordingly, so a 35-day cycle nudges your estimated ovulation and due date about a week later than a 28-day cycle would.