Tools
Baby size by week
The whole chart on one page — and the actual number beside every comparison.
Most size charts hand you a piece of fruit and nothing else. This one prints the measurement in centimetres and inches next to the drawing, because a comparison you cannot check is a comparison you have to take on faith.
How these are measured
Up to week 19 a baby is measured crown to rump — the top of the head to the bottom of the torso — because the legs are curled and cannot be measured reliably. From week 20 the measurement is head to heel, which is why the numbers jump between those two rows. It is a change of ruler, not a growth spurt.
Weeks one to three are dated from before conception and carry no size at all. Week four is the implantation week, described in the clinical source as approximately the size of a pinhead with no figure given, so none is printed here.
| Week | Drawn as | Length | Measured | |
|---|---|---|---|---|
| 1 | A seed, held | No size stated | — | Week 1 → |
| 2 | The seed in soil | No size stated | — | Week 2 → |
| 3 | First root, unseen | No size stated | — | Week 3 → |
| 4 | Baby's-breath floret | No size stated | — | Week 4 → |
| 5 | Lilac floret | 0.2 cm (0.1 in) | Crown to rump | Week 5 → |
| 6 | Forget-me-not | 0.5 cm (0.2 in) | Crown to rump | Week 6 → |
| 7 | Lily-of-the-valley bell | 1 cm (0.4 in) | Crown to rump | Week 7 → |
| 8 | Violet | 1.6 cm (0.6 in) | Crown to rump | Week 8 → |
| 9 | Chamomile bloom | 2.3 cm (0.9 in) | Crown to rump | Week 9 → |
| 10 | Cherry blossom | 3.1 cm (1.2 in) | Crown to rump | Week 10 → |
| 11 | Crocus | 4.1 cm (1.6 in) | Crown to rump | Week 11 → |
| 12 | Daffodil | 5.4 cm (2.1 in) | Crown to rump | Week 12 → |
| 13 | Tulip bloom | 6.7 cm (2.6 in) | Crown to rump | Week 13 → |
| Week | Drawn as | Length | Measured | |
|---|---|---|---|---|
| 14 | Magnolia bloom | 8.7 cm (3.4 in) | Crown to rump | Week 14 → |
| 15 | Pansy | 10.1 cm (4.0 in) | Crown to rump | Week 15 → |
| 16 | Gerbera daisy | 11.6 cm (4.6 in) | Crown to rump | Week 16 → |
| 17 | Bearded iris | 13 cm (5.1 in) | Crown to rump | Week 17 → |
| 18 | Water lily | 14.2 cm (5.6 in) | Crown to rump | Week 18 → |
| 19 | Hibiscus | 15.3 cm (6.0 in) | Crown to rump | Week 19 → |
| 20 | Sweet pea, full stem | 25.6 cm (10.1 in) | Head to heel | Week 20 → |
| 21 | Anemone | 27.4 cm (10.8 in) | Head to heel | Week 21 → |
| 22 | Morning glory | 29 cm (11.4 in) | Head to heel | Week 22 → |
| 23 | Freesia | 30.6 cm (12.0 in) | Head to heel | Week 23 → |
| 24 | Marigold | 32.2 cm (12.7 in) | Head to heel | Week 24 → |
| 25 | Begonia | 33.7 cm (13.3 in) | Head to heel | Week 25 → |
| 26 | Lavender sprig | 35.1 cm (13.8 in) | Head to heel | Week 26 → |
| 27 | Calla lily | 36.6 cm (14.4 in) | Head to heel | Week 27 → |
| Week | Drawn as | Length | Measured | |
|---|---|---|---|---|
| 28 | Iceland poppy | 37.6 cm (14.8 in) | Head to heel | Week 28 → |
| 29 | Cosmos | 39.2 cm (15.4 in) | Head to heel | Week 29 → |
| 30 | Zinnia | 40.5 cm (15.9 in) | Head to heel | Week 30 → |
| 31 | Black-eyed Susan | 41.8 cm (16.5 in) | Head to heel | Week 31 → |
| 32 | Aster | 43 cm (16.9 in) | Head to heel | Week 32 → |
| 33 | Hydrangea stem | 43.7 cm (17.2 in) | Head to heel | Week 33 → |
| 34 | Snapdragon | 45 cm (17.7 in) | Head to heel | Week 34 → |
| 35 | Dahlia, full stem | 46.2 cm (18.2 in) | Head to heel | Week 35 → |
| 36 | Peony, full stem | 47.4 cm (18.7 in) | Head to heel | Week 36 → |
| 37 | Orchid spike | 48.6 cm (19.1 in) | Head to heel | Week 37 → |
| 38 | Stargazer lily stem | 49.2 cm (19.4 in) | Head to heel | Week 38 → |
| 39 | Sunflower, cut stem | 50.1 cm (19.7 in) | Head to heel | Week 39 → |
| 40 | Long-stemmed rose | 51.2 cm (20.2 in) | Head to heel | Week 40 → |
Why these are averages
Every figure here is a typical measurement for that week. Real babies vary considerably, and a baby measuring above or below one of these numbers is usually just a baby. What matters clinically is the pattern of growth over time, which your midwife or doctor is tracking, and not a single row of a chart on the internet.
If a scan has given you a measurement that worries you, the person to ask is the one who took it.
Where this came from
See it at actual size
Zohra draws each of these flowers at the real measurement on your phone, so the number stops being abstract.
Zohra arrives on the App Store for iPhone shortly. Everything on this site is free to read now, with no account and no sign-up.