Bodysuit, onesie, vest, sleepsuit, babygrow, romper, footie — baby clothing terms are thrown around as if everyone was handed a glossary at birth. They weren't. For a first-time parent building a wardrobe (or a relative buying a gift), the vocabulary alone is genuinely confusing, and the terms even change between the US and UK for the same garment. This guide clears it up: what each baby clothing item actually is, when to use it, and how many you really need.
Bodysuit (a.k.a. Onesie / Vest)
What it is: A close-fitting one-piece that covers the torso and fastens with poppers at the crotch. It has no legs (and either short or long sleeves, or sleeveless). In the US it's commonly called a “onesie”; in the UK, a “vest” or “bodysuit”.
When to use it: The everyday base layer. Worn on its own in warm weather, or under other clothes for warmth. The crotch poppers keep it tucked in and make nappy changes easy.
How many: A lot — 6–8 per size. They're the workhorse and you'll change them often.
Sleepsuit (a.k.a. Babygrow / Footie / Footed Romper)
What it is: A one-piece that covers the whole body including the legs and usually the feet, fastening with poppers or a zip down the front and along the legs. In the US it's often a “sleeper” or “footie”; in the UK, a “sleepsuit” or “babygrow”.
When to use it: The other everyday essential — newborns practically live in these, day and night, because they're warm, cozy, and cover the feet without separate socks. Ideal for sleep and cooler days.
How many: 6–8 per size in the early months. Front-opening, easy-change designs are best.
Romper
What it is: A one-piece that combines a top and shorts (or short legs) in a single garment, usually without covering the feet. Often a bit more “styled” than a plain sleepsuit — think collars, prints, and outfit-like designs.
When to use it: A step up from the basics — great for warm weather, daytime outfits, outings, and photos, while still being a practical one-piece that's easy to wear.
How many: A handful — these are the “outfit” pieces rather than the round-the-clock basics.
The Other Terms You’ll See
- Two-piece set: A separate top and bottom — cute for older babies, but fiddlier on a newborn than a one-piece.
- Sleep sack / wearable blanket: A sleeveless wearable blanket worn over sleepwear for safe, blanket-free warmth at night (see our sleepwear guide).
- Pramsuit / snowsuit: A padded all-in-one outer layer for cold-weather outings (not for car seats — see our winter guide).
- Dungarees / overalls: Trousers with a bib and straps, worn over a bodysuit.
- Scratch mittens: Tiny mittens to stop newborns scratching their faces.
How They Work Together
The simplest way to think about a baby's wardrobe: bodysuits and sleepsuits are the foundation (buy the most of these), rompers and outfits are the next layer for daytime and going out, and sleep sacks and outerwear handle sleep and weather. Layer a bodysuit under a sleepsuit for warmth; swap to a romper for an outing; add a cardigan or pramsuit for the cold.
A Quick Buying Summary
- Stock up on: bodysuits and sleepsuits (6–8 each per size) — the everyday essentials
- Buy a handful of: rompers and outfits for daytime and occasions
- A couple of: sleep sacks, plus a weather-appropriate outer layer
- Prioritise: front-opening, easy-change designs in soft cotton — and don't overbuy the smallest sizes (see our layette checklist)
The Bottom Line
Once you can tell a bodysuit from a sleepsuit from a romper, building a baby's wardrobe gets a lot less daunting. Bodysuits and sleepsuits are the everyday foundation; rompers are the easy outfits on top; everything else handles sleep and weather. Buy the basics generously, the outfits sparingly, and choose soft, easy-change cotton throughout.
Browse our soft cotton bodysuits, rompers, and everyday basics in the collections, and see our layette checklist for exactly how many of each to buy.