Weights from 10 weeks follow the Hadlock fetal growth standard (50th percentile); lengths are crown-rump to 13 weeks, crown-heel after. Every baby grows at its own pace.
| Week | Average weight | Average length |
|---|---|---|
| Week 12 | 14 g | 5.4 cm |
| Week 16 | 146 g | 18.6 cm |
| Week 20 | 331 g | 25.6 cm |
| Week 24 | 670 g | 30 cm |
| Week 28 | 1.21 kg | 37.6 cm |
| Week 32 | 1.95 kg | 42.4 cm |
| Week 36 | 2.81 kg | 47.4 cm |
| Week 40 ← you | 3.62 kg | 51.2 cm |
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How big is my baby this week? Enter the week of pregnancy to see the average fetal weight and length, the usual range and what the baby is about the size of.
Weights from 10 weeks follow the Hadlock fetal growth standard used by ultrasound machines. Babies grow fastest in the third trimester, gaining about 200 g a week from week 30.
| Week of Pregnancy | 20 weeks |
| Baby's average weight at 20 weeks | 331 g (11.7 oz) |
| Average length | 25.6 cm (10.1 in), crown-to-heel length |
| About the size of | a banana |
| Trimester | Second |
| Normal range (10th–90th, approx.) | 281 – 387 g |
331 g (11.7 oz); 25.6 cm (10.1 in), crown-to-heel length.
Try this example →| Week of Pregnancy | 32 weeks |
| Baby's average weight at 32 weeks | 1.95 kg (4.31 lb) |
| Average length | 42.4 cm (16.7 in), crown-to-heel length |
| About the size of | a jicama |
| Trimester | Third |
| Normal range (10th–90th, approx.) | 1,660 – 2,285 g |
1.95 kg (4.31 lb).
Try this example →| Week of Pregnancy | 40 weeks |
| Baby's average weight at 40 weeks | 3.62 kg (7.98 lb) |
| Average length | 51.2 cm (20.2 in), crown-to-heel length |
| About the size of | a small pumpkin |
| Trimester | Third |
| Normal range (10th–90th, approx.) | 3,076 – 4,234 g |
3.62 kg (7.98 lb).
Try this example →About 330 g (11.7 oz), roughly the weight of a banana, and about 25.6 cm long from head to heel.
About 2.8 kg (6.2 lb) on average.
Before 14 weeks babies are measured crown to rump (sitting height); from then on, head to heel.