See your current week, trimester and baby size comparison instantly.
Estimates based on a standard 40-week pregnancy.
Pregnancy is usually measured in weeks rather than months, which can feel confusing at first. A full-term pregnancy is generally counted as 40 weeks, starting not from conception, but from the first day of the last menstrual period (LMP). This counting method might seem unusual, but it is the standard used by doctors and midwives worldwide, mainly because the exact date of conception is often unknown, while the start of the last period is easier to recall.
Our Pregnancy Tracker lets you calculate your current week, trimester, estimated due date and days remaining, using whichever starting point you know: your last period, your conception date, or an already-confirmed due date. It also shows a fun weekly baby size comparison. It is free, works on any device and needs no sign-up.
Pregnancy is divided into gestational age, counted from the first day of the last menstrual period, which is what most trackers, apps and doctors use by default. This means that in the first two weeks of "pregnancy" by this counting method, conception has often not even happened yet, since ovulation and conception typically occur around week 2. If you know your conception date instead, this tracker automatically adjusts by adding roughly 2 weeks to align with the standard gestational counting system.
Knowing exactly which week you are in helps you understand what developmental milestones are happening, what symptoms are typical at that stage, which prenatal tests are usually scheduled around that time, and roughly how much longer until your due date. It also makes conversations with your care provider clearer, since most pregnancy guidance, screening schedules and appointment timing are organized by week rather than by month.
| Trimester | Weeks | What's Happening |
|---|---|---|
| First Trimester | Week 1 - Week 13 | Major organ development; higher miscarriage risk period; morning sickness is common |
| Second Trimester | Week 14 - Week 27 | Often called the "golden period"; energy often improves; anatomy scan usually happens |
| Third Trimester | Week 28 - Week 40+ | Rapid weight gain for baby; more frequent prenatal visits; preparing for labor |
The progress bar above shows how far along you are toward the standard 40-week mark, based on the date you entered. It highlights your current trimester automatically, so you can see at a glance both your percentage complete and which stage of pregnancy you are in. Since actual delivery can happen anywhere from around week 37 (considered full term) to slightly past week 40, treat the 100% mark as an estimate rather than a fixed deadline.
The standard method, called Naegele's Rule, estimates the due date as 280 days (40 weeks) after the first day of the last menstrual period. If you enter a conception date instead, roughly 266 days (38 weeks) are added, since conception typically occurs about 2 weeks after the last period began in a standard cycle.
Example: last period started January 1. Adding 280 days gives an estimated due date around October 8 of the same year.
| Category | Timing |
|---|---|
| Preterm | Before 37 weeks |
| Early Term | 37 weeks 0 days to 38 weeks 6 days |
| Full Term | 39 weeks 0 days to 40 weeks 6 days |
| Late Term | 41 weeks 0 days to 41 weeks 6 days |
| Post-Term | 42 weeks and beyond |
These categories, defined by major medical organizations, help providers make decisions about monitoring and, if needed, timing of delivery. Your provider will discuss what applies to your specific situation as your due date approaches.
| Week | Approximate Size Comparison |
|---|---|
| Week 8 | Raspberry |
| Week 12 | Lime |
| Week 16 | Avocado |
| Week 20 | Banana |
| Week 24 | Corn on the cob |
| Week 28 | Eggplant |
| Week 32 | Squash |
| Week 36 | Romaine lettuce (head) |
| Week 40 | Small pumpkin |
These comparisons are a fun, approximate way to visualize growth and are widely used in pregnancy apps and books. Actual baby size varies from pregnancy to pregnancy, and your provider's measurements during appointments are the accurate source of size and growth tracking.
The neural tube, heart, and major organs begin forming. Morning sickness, fatigue and breast tenderness are common. The first prenatal visit and early screening tests usually happen during this period.
Many people feel noticeably better, with more energy and reduced nausea. Fetal movement, sometimes called "quickening," is often first felt between weeks 16 and 25. The detailed anatomy ultrasound usually takes place around weeks 18-22.
The baby gains most of its birth weight during this stage. Prenatal visits become more frequent, and preparation for labor, delivery and the hospital bag typically ramps up.
Every pregnancy is different, and not everyone experiences the same symptoms, but some patterns are common at each stage:
If any symptom feels severe, unusual, or concerning, contact your provider rather than waiting, since only they can properly assess what is typical for your specific pregnancy.
Tracking pregnancy week by week helps you understand what stage you are in, what to expect, and roughly how much time remains until your due date. Use the tracker above to check your progress anytime, and pair it with regular visits to your doctor or midwife for accurate, personalized care throughout your pregnancy.