Which baby bodysuit size should you choose? A guide from 0 to 18 months
If you only know your child’s age, you can use the age-based size as a first guide - but the best way to determine the right baby bodysuit size is to consider your 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.
Lilla Villa has several bodysuit styles currently available in sizes 0-3 months, 4-7 months, 8-12 months and 12-18 months. Use age as a starting point, then check the fit on your child.
Baby bodysuit sizes from 0 to 18 months
| Size | Typical starting point | What to check |
|---|---|---|
| 0-3 months | The first few months | Room for the diaper and a soft fit around the shoulders and thighs |
| 4-7 months | When your baby grows quickly in length | That the bodysuit fastens without pulling at 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 your child sits, crawls or walks |
As a general guide, Mødrehjælpen states that the clothes in its baby starter packs are typically around size 50-62 for ages 0-4 months. This also shows why age alone isn’t enough: children grow at different rates, and brands don’t always use exactly the same sizing system.
How to check whether the bodysuit fits
A bodysuit should fit snugly enough to stay in place, but not so snugly that it feels tight. When trying it on your child, you can check the following:
- The snaps at the bottom should fasten without having to pull them tightly together.
- The fabric must not feel noticeably tight across the shoulders, tummy or thighs.
- There should be plenty of room for the diaper, even when your child moves.
- The bodysuit must not pull up at the crotch when your child is lying down, sitting or crawling.
- The armholes and neckline should fit comfortably without digging in.
Signs that the bodysuit has become too small
The clearest sign is often the length. If the fastening at the bottom starts to pull, or the fabric feels tight across the shoulders, it’s usually time for the next size up. You may also notice that the bodysuit leaves visible marks around the legs or shoulders, or that your child seems uncomfortable when moving.
Should you choose a larger size?
Not necessarily. An oversized bodysuit can bunch up under clothes, ride up or fit poorly around the diaper. If your baby is between sizes, it’s better to assess the length and fit rather than simply choosing a larger size “to grow into.” A little extra room can be practical for fast-growing babies, but the bodysuit should still stay in place.
Bodysuit or sleepsuit - which is easier 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.
Also read 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 Velvet Rib Look, Floral Print and Lace Trim are currently available in the four age-based sizes above. Always check the individual product page before ordering, as sizes and fit can vary between styles.
Frequently asked questions
What matters most: age or length?
Age is only a starting point. Your baby’s length and the actual fit of the bodysuit matter more, especially if your baby is taller, shorter, slimmer or bigger than average for their age.
How do I know if there’s enough room for the diaper?
The bodysuit should fasten easily without the fabric pulling tightly down from the shoulders. When your baby 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 in just a few weeks. Pay particular attention to the length of the body and whether the fastening at the bottom still feels comfortable.
Remember: the specific product page is the most important
Use this guide to help you choose the first size, but always check the sizes, material and any product measurements for the specific bodysuit. Fit can vary between styles, even when they have the same size label.
More guides to baby bodysuits and baby clothes
See our practical guides to baby clothes and find current baby bodysuits at Lilla Villa.