Baby size by week: from poppy seed to watermelon
"Your baby is the size of a banana" — the fruit comparison is one of the most loved rituals of pregnancy. Here's how the week-by-week sizes work, and how to see yours at a glance.
Why fruit comparisons work
Centimetres and grams are hard to picture; a lime is not. Comparing your baby to a familiar fruit or object turns abstract measurements into something you can hold in your hand — and gives every week a little moment worth sharing.
Milestone sizes through the 40 weeks
| Week | Comparison | Approx. length | Approx. weight |
|---|---|---|---|
| 4 | Poppy seed | ~1 mm | <1 g |
| 8 | Raspberry | ~1.6 cm | ~1 g |
| 12 | Lime | ~5.4 cm | ~14 g |
| 16 | Avocado | ~11.6 cm | ~100 g |
| 20 | Banana | ~26 cm | ~300 g |
| 24 | Ear of corn | ~30 cm | ~600 g |
| 28 | Eggplant | ~37 cm | ~1 kg |
| 32 | Squash | ~42 cm | ~1.7 kg |
| 36 | Romaine lettuce | ~47 cm | ~2.6 kg |
| 40 | Watermelon | ~51 cm | ~3.4 kg |
Every baby grows at their own pace — these are typical reference values, not targets. Your provider tracks your baby's actual growth at your scans.
More than just size
Each week also brings development milestones: around week 20 many babies can distinguish light from dark and you may start feeling regular kicks; by the third trimester they're practising breathing movements. Size is the headline — the development story underneath is the good part.
See your baby's size every week in Lunera
Lunera includes 40 size comparisons — one for every week — from poppy seed to watermelon, each with a beautiful illustration, typical length and weight, a development highlight, and a note on how you might be feeling.
- The current comparison sits right on your home screen and widgets
- Weekly notifications announce each new size ("Week 21 begins — your baby is about the size of a carrot")
- With Lunera PRO's Week Explorer you can browse all 40 weeks, including the ones ahead
Quick answers
How accurate are the fruit size comparisons?
They're approximations based on average fetal measurements for each week. Babies vary — the comparisons are for fun and perspective, while your ultrasounds measure actual growth.
When can I feel my baby move?
Many people feel the first movements between weeks 16 and 25 — often around week 20, when the baby is about banana-sized. Second pregnancies often notice movement earlier.
Track your pregnancy with Lunera
Week-by-week baby development, due date countdown, widgets, and a one-tap contraction timer — free, private, and subscription-free on iPhone.
This guide is for informational and educational purposes only and is not medical advice. Lunera is not a medical device. Always consult your doctor, midwife, or healthcare provider with any questions about your pregnancy or labor.