Pregnancy Week Calculator โ Baby Size, Bump & Symptoms by Week
Find your exact pregnancy week, your baby's fruit-size comparison, common symptoms, and bump progress โ free, private, no sign-up.
Already know your due date? Try our Due Date Calculator ยท Read our medical disclaimer
Don't know your last period date? Use your due date instead
Why Track Your Pregnancy Week by Week?
Pregnancy moves fast, and a lot changes between one appointment and the next. Checking in week by week helps you:
- Know what's normal for your exact stage โ symptoms that feel alarming are often completely expected at a given week, and this tool tells you which.
- Visualize your baby's growth with a simple fruit-size comparison and a one-line fetal development update, rather than trying to picture abstract measurements.
- Plan ahead for key milestones โ like your anatomy scan, glucose screening, or when to start kick counts โ before they sneak up on you.
- Track your own changes too, from when a bump typically appears to realistic weight-gain and symptom expectations by trimester.
How This Calculator Works
Enter the first day of your last period (or your due date, if that's what you know). The tool calculates your current week and day using the standard 280-day (40-week) pregnancy length, then matches that week to a database of fruit-size comparisons, fetal development milestones, common symptoms, and bump notes — all updated instantly, right in your browser. Nothing you enter is sent to our servers or stored.
Pregnancy Bump, Weight Gain & Baby Size by Week
Every pregnancy shows differently โ body shape, muscle tone, and whether it's a first pregnancy all affect when a bump by week becomes visible. Most first-time mothers notice a true bump between weeks 12-16, while a second or third pregnancy often shows earlier, around weeks 8-10, since the abdominal muscles have stretched before.
Total pregnancy weight gain by week is usually modest in the first trimester (around 1-4 lbs total) and then averages roughly 1 lb per week through the second and third trimesters for an average pre-pregnancy BMI โ though your provider will give you a personalized target based on your individual health. Our full Pregnancy Week by Week guide covers trimester-by-trimester symptoms, hormone changes, and a full checklist by week.
Pregnant with Twins?
Twin pregnancies follow the same week-by-week dating, but the bump typically shows earlier and grows faster, weight gain targets are usually higher, and twins are commonly delivered earlier (around 36-38 weeks) than a single pregnancy. Use the calculator above the same way, and ask your provider for twin-specific guidance on weight gain and monitoring.
After Baby Arrives
Once your due date passes and baby is here, your next stop is our Postpartum Recovery Guide, the Baby Name Meaning Finder if you're still deciding on a name, and our Baby Weight Percentile Calculator to track growth after birth.
Frequently Asked Questions
How do I know what week of pregnancy I am in?
Enter the first day of your last period (or your due date, if you know it) into the calculator above. It instantly shows your current week, day, trimester, and your baby's approximate fruit-size comparison for that week.
What size is my baby compared to fruit by week?
Early weeks compare to a poppy seed or blueberry, mid-pregnancy to an avocado or mango, and by the third trimester your baby is roughly the size of a watermelon. Scroll to your current week above for the exact comparison.
When does the pregnancy belly or bump usually start showing?
Most first-time mothers start showing a noticeable bump between weeks 12 and 16, while in later pregnancies it can show earlier, sometimes by week 8-10, since the abdominal muscles have already stretched once.
How much weight should I gain by week during pregnancy?
For an average pre-pregnancy BMI, total gain is typically 25-35 lbs (11-16 kg) across the full pregnancy โ roughly 1-4 lbs in the first trimester, then about 1 lb per week through the second and third trimesters. Your provider will tailor this to your individual BMI and health.
Is this calculator accurate for twin pregnancies?
The week-by-week dating works the same for twin pregnancies, though twin pregnancies are typically delivered earlier (around 36-38 weeks) and weight gain recommendations are usually higher โ ask your provider for personalized targets.
What is my baby developing each week?
Development moves fast and in a predictable order โ the heartbeat starts around week 6, major organs form by week 8, movement begins around week 9 (though you won't feel it until later), and lungs mature in the final weeks before birth. Enter your date above to see the specific milestone for your current week.
Does this calculator store or share my information?
No. All calculations happen directly in your browser using JavaScript โ the dates you enter are never sent to our servers, stored, or shared.
Track movement with our Kick Counter, or time labor with our Contraction Timer.
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