Which baby bodysuit size should you choose? A guide from 0 to 18 months
If you only know the child’s age, you can use the age size as a starting point - but the right baby bodysuit size is best determined by the child’s length, build and the fit of the specific style. The bodysuit should fasten without pulling, have room for the diaper and allow free movement around the shoulders, tummy and legs.
At Lilla Villa, several current bodysuit styles are available in sizes 0-3 months, 4-7 months, 8-12 months and 12-18 months. Use the age as a starting point, then check the fit on the child.
Baby bodysuit sizes from 0 to 18 months
| Size | Typical starting point | What to check |
|---|---|---|
| 0-3 months | The first months | Room for the diaper and a soft fit around the shoulders and thighs |
| 4-7 months | When the baby is growing quickly in length | That the bodysuit can fasten without pulling in the crotch |
| 8-12 months | More movement, play and wriggling | Freedom around the tummy, hips and legs |
| 12-18 months | A more active child | That the length still fits when the child sits, crawls or walks |
As a general guide, Mødrehjælpen states that the clothing in its baby starter packages is typically around size 50-62 for 0-4 months. This also shows why age alone is not enough: children grow differently, and brands do not always use exactly the same sizing system.
How to check whether the bodysuit fits
A bodysuit should fit closely enough to stay in place, but not so closely that it feels tight. When trying it on the child, check the following:
- The snaps at the bottom should fasten without being pulled tightly together.
- The fabric must not visibly tighten across the shoulders, tummy or thighs.
- There should be plenty of room for the diaper, even when the child moves.
- The bodysuit must not pull up in the crotch when the child lies down, sits or crawls.
- The armholes and neckline should feel comfortable without cutting into the skin.
Signs that the bodysuit has become too small
The most obvious sign is often the length. If the fastening at the bottom starts to pull, or the fabric feels tight across the shoulders, it is usually time for the next size. You may also notice that the bodysuit leaves clear marks around the legs or shoulders, or that the child seems uncomfortable while moving.
Should you choose a larger size?
Not automatically. A bodysuit that is too large can bunch up under clothing, ride up or fit poorly around the diaper. If the child is between two sizes, it is better to assess the length and fit rather than simply choosing the larger size “to allow room to grow”. For fast-growing babies, a little extra room can be practical, but the bodysuit should still stay securely in place.
Bodysuit or sleepsuit - which is easiest for everyday use?
A bodysuit works well as a base layer under trousers, leggings or a cardigan because it stays in place around the tummy. A sleepsuit combines the top and legs in one piece and can be practical for quiet days, naps or as a complete outfit.
Read also Baby bodysuit or sleepsuit? How to choose the right clothes for your baby.
Examples from Lilla Villa’s current bodysuit styles
Our 100% Cotton Baby Bodysuit with Floral Print and Puff Sleeves and 100% Cotton Baby Bodysuit with Corduroy Rib Look, Floral Print and Lace Trim are currently available in the four age sizes listed above. Always check the individual product page before ordering, as sizes and fit may vary between styles.
Frequently asked questions
What matters most: age or length?
Age is only a starting point. The child’s length and the actual fit of the bodysuit are more important, especially if the child is taller, shorter, slimmer or larger than average for their age.
How do I know whether there is enough room for the diaper?
The bodysuit should fasten easily without the fabric pulling sharply down from the shoulders. When the child moves their legs, there should still be room around the hips and diaper.
How often should you check the size?
During periods of rapid growth, the fit can change within a few weeks. Pay particular attention to the length of the body and whether the fastening at the bottom still feels comfortable.
Remember: the individual product page matters most
Use this guide to help choose the initial size, but always check the sizes, material and any product measurements for the specific bodysuit. The fit may vary between styles, even when the size name is the same.
More guides about baby bodysuits and baby clothes
See our practical guides to baby clothes and find current baby bodysuits at Lilla Villa.