baby weight chart during pregnancy in kg?

Average fetal length and weight chart
Joanne
by Joanne Lewsley | animated_fact_check Medically reviewed by Chess Thomas, Research Editor | September 2019
Woman having her bump measured
iStock.com / yacobchuk
During pregnancy, you’ll see your bump get bigger as your baby develops inside your womb (uterus). By 40 weeks, the average baby weighs 3.5kg (7.6lb), and is about 51.2cm (20.2in) long from head to heel. But how big is your baby right now? We’ve put together this simple chart to tell you the length and weight of an average baby from eight weeks of pregnancy, through to birth.

Bear in mind that boys tend to be longer and heavier than girls and that every baby is different. So don’t worry if the measurements in your maternity notes are different from those listed below. Your baby’s growth will be checked during your pregnancy at the appointments below:

During your dating scan at around 12 weeks, your sonographer will measure your baby from her head to her bottom. This is called the crown-rump length (CRL), and it will be used to work out your due date. At your anomaly scan, which you’ll have at around 20 weeks, your baby will be more active, meaning CRL isn’t as accurate. Instead, your sonographer will check your baby’s head circumference (HC), abdominal circumference (AC) and thigh bone (femur) length (FL).

To keep things simple, our chart uses crown-rump length measurements from eight weeks to 19 weeks, then crown-to-heel measurements until 42 weeks.

Pregnancy week Length (inches) Weight (ounces) Length (cm) Mass (g)
8 weeks 0.6in 0.04oz 1.6cm 1g
9 weeks 0.9in 0.07oz 2.3cm 2g
10 weeks 1.2in 0.1oz 3.1cm 4g
11 weeks 1.6in 0.2oz 4.1cm 7g
12 weeks 2.1in 0.5oz 5.4cm 14g
13 weeks 2.9in 0.8oz 7.4cm 23g
14 weeks 3.4in 1.5oz 8.7cm 43g
15 weeks 4in 2.5oz 10.1cm 70g
16 weeks 4.6in 3.5oz 11.6cm 100g
17 weeks 5.1in 4.9oz 13cm 140g
18 weeks 5.6in 6.7oz 14.2cm 190g
19 weeks 6in 8.5oz 15.3cm 240g


The lengths below are from crown to heel:

Pregnancy week Length (inches) Weight (ounces) Length (cm) Mass (g/kg)
20 weeks 10in 10.6oz 25.6cm 300g
21 weeks 10.5in 12.7oz 26.7cm 360g
22 weeks 10.9in 15.2oz 27.8cm 430g
23 weeks 11.4in 1.1lb 28.9cm 500g
24 weeks 11.8in 1.3lb 30cm 600g
25 weeks 13.6in 1.5lb 34.6cm 660g
26 weeks 14in 1.7lb 35.6cm 760g
27 weeks 14.4in 1.9lb 36.6cm 875g
28 weeks 14.8in 2.2lb 37.6cm 1kg
29 weeks 15.2in 2.5lb 38.6cm 1.2kg
30 weeks 15.7in 2.9lb 39.9cm 1.3kg
31 weeks 16.2in 3.3lb 41.1cm 1.5kg
32 weeks 16.7in 3.7lb 42.4cm 1.7kg
33 weeks 17.2in 4.2lb 43.7cm 1.9kg
34 weeks 17.7in 4.7lb 45cm 2.1kg
35 weeks 18.2in 5.3lb 46.2cm 2.4kg
36 weeks 18.7in 5.7lb 47.4cm 2.6kg
37 weeks 19.1in 6.3lb 48.6cm 2.9kg
38 weeks 19.6in 6.8lb 49.8cm 3.1kg
39 weeks 20in 7.2lb 50.7cm 3.3kg
40 weeks 20.2in 7.6lb 51.2cm 3.5kg
41 weeks 20.3in 7.9lb 51.5cm 3.6kg
42 weeks 20.3in 8.1lb 51.7cm 3.7kg


More on your growing baby:

See how big your baby is now in our fruit and veg comparison slideshow.
Check out our week-by-week guide to fetal development.
Learn what it might mean if your baby is smaller or larger than average.

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Joanne Lewsley
Joanne Lewsley
Joanne Lewsley is a freelance copywriter and editor, and specialises in creating evidence-based parenting, health and lifestyle web content.