Measure your baby’s length and weight before you buy anything: age on the label is only a rough guide. For most newborns, 000 fits well, while smaller babies often need 0000. When your baby sits between two labels, size up. Buy a handful of pieces per size since babies outgrow them fast; to help with choosing the right fabrics for warm months, see our advice on the best muslin swaddles for Australian summer.
TL;DR:
- Babies may require sizing up if their measurements fall between two labels, especially when factoring in cloth nappy bulk and growth pace.
- Accurate length, weight, and head circumference measurements taken at home are essential to select the right size, particularly before shopping.
- European brands often use centimetre-based sizing, so measurements are necessary rather than relying solely on age or label numbers.
- For safe and comfortable fit, choose close-fitting sleepwear with stretch fabric, avoid loose styles, and buy only a few piece per size to accommodate rapid growth.
- Growth during the first year is uneven, making measurement-based selection more reliable than age labels, and leaning on store return policies can help manage sizing errors.
Table of Contents
- AU baby size chart: labels, measurements and shopping notes
- How to measure length, weight and head circumference correctly at home
- Why age labels are only a guide, and how to convert EU sizes
- Fit rules, safety notes and a smarter way to shop
- Baby Goes Retro’s approach to sizing and product notes
- Sensible expectations for sizes in the first year
- Where to shop the sizes covered in this guide
- Sources
- FAQ
AU baby size chart: labels, measurements and shopping notes
Australian baby clothes use a simple size code rather than an age alone, though age ranges are printed alongside for convenience. Here is the standard progression you will see across most Australian retailers:
- 00000 (premmie): for very small or premature babies, generally for the smallest newborns.
- 0000 (newborn): suits most new babies in the first weeks.
- 000 (0 to 3 months): the size many families jump straight into if their baby is a larger newborn.
- 00 (3 to 6 months): a good buy-ahead size given how fast babies grow.
- 0 to 3 months and 3 to 6 months: used interchangeably with 000 and 00 by some brands, which is where the confusion starts.
- 6 to 12 months: covers a wide window, so check the garment’s own measurements before assuming it will fit.
Head circumference at birth for a healthy, full-term baby is generally within the range of 33 to 37 centimetres and should be considered alongside weight and length rather than on its own when working out what to buy, according to the AIHW’s research brief on head circumference.
European brands rarely use the 0000/000 system. Many size by centimetre length or by their own EU numbering, so a “50” or “56” tag means nothing until you check the brand’s own measurements. Our guide to EU baby sizes and AU conversions walks through exactly how to translate those tags for Australian shopping.
If you are using cloth nappies, factor in extra room through the seat and rise. Standard bodysuits and rompers can fit tighter than expected once a cloth nappy is on, so sizing up one label is common. Our piece on cloth diaper friendly clothing covers which cuts work best.
How to measure length, weight and head circumference correctly at home
Getting an accurate measurement takes two minutes and saves you a wardrobe of ill-fitting clothes. Follow these steps:
- Lay your baby flat on their back on a firm surface and gently straighten one leg to measure from the top of the head to the heel.
- Weigh your baby with a nappy on only, using bathroom scales if a baby scale is not on hand, and subtract the nappy’s weight if you want a precise figure.
- Wrap a soft tape measure around the widest part of the head, just above the eyebrows and ears, to get head circumference.
- Record all three figures and compare them against the brand’s own size chart rather than the age printed on the label.
Length matters most for bodysuits, rompers and anything with legs. Head circumference matters most for hats and hooded jackets. Weight is the figure most brands rely on for their overall size chart, so it is the one to check first when in doubt.
You do not need to remeasure weekly. WA community health guidance notes that serial measurements taken at routine child health checks give the clearest picture of growth, so lean on those results between check-ins and remeasure yourself only when you are about to buy, according to CAHS WA’s growth guidance.
Pro Tip: Measure just before you shop, not weeks in advance. A newborn’s measurements can shift enough in a fortnight to jump a whole size.
Why age labels are only a guide, and how to convert EU sizes
Age labels are a starting point, not a rule. Two babies both called “newborn” can differ by several centimetres in length and more than a kilogram in weight, which is exactly why 0000 and 000 overlap so much on shelves.
- 0000 usually suits smaller or premature newborns, while 000 often suits an average or larger newborn from day one.
- 00 is worth buying ahead of time for any baby, since most infants move through it quickly.
- Premature babies may need 00000 for weeks longer than expected, so always check current weight rather than corrected age.
- Larger newborns can skip 0000 altogether and go straight into 000 or even 00.
For European labels, measure first and match centimetres rather than trust the printed age. Our measure-first EU to AU conversion guide breaks down exact centimetre equivalents so European brands fit as reliably as local ones.
Fit rules, safety notes and a smarter way to shop
A few habits keep your baby comfortable and your wardrobe manageable.
- Choose close-fitting sleepwear over loose, flowing styles, and avoid long ribbons, ties or drawstrings that could pose a strangulation risk.
- Size up when a garment feels snug through the nappy area or restricts leg movement, but keep sleepwear closer fitting for safer comfort.
- Buy a small capsule, three or four bodysuits and a couple of rompers per size, rather than a full wardrobe in one go.
- Favour stretch cotton and snap or zip closures over buttons, since they adjust more easily as your baby grows and make nappy changes faster.
Pro Tip: Stretch fabrics like organic cotton jersey give you a few extra weeks in each size before you need to size up.
Baby Goes Retro’s approach to sizing and product notes
The retailer specialises in premium European organic baby and kids’ clothing. We measure garments flat, recording internal length and chest width rather than the stretched-out figure, so what you see on our size chart is what you actually get.
- The Frugi Fun Flowers Bodysuits (2-Pack) are a soft organic cotton option that suits newborn through to early 000 sizing.
- The Kite Koala Time Baby Gift Bundle is a popular newborn gift set with generous stretch for those first unpredictable weeks.
- The DUNS Sweden Clover Playsuit: Sulphur Green has a relaxed, stretchy cut that gives extra room for cloth nappies without sizing all the way up.
Sensible expectations for sizes in the first year
Buy less than you think you need, measure before every purchase, and lean on returns when a size misses the mark. Growth in the first year is genuinely uneven, so treat every label as a starting point rather than a promise. Get the measuring tape out before the size guide.
— Daniel
Where to shop the sizes covered in this guide
This retailer stocks newborn and 000 sizes from European organic brands chosen for colour and comfort rather than the usual beige.
- The Frugi Fun Flowers Bodysuits (2-Pack) suit newborns through early 000 and come in bright, non-beige prints.
- The Kite Koala Time Baby Gift Bundle makes an easy newborn gift with room to grow.
- The DUNS Sweden Clover Playsuit: Sulphur Green offers a stretchy, cloth-nappy-friendly fit.
- Browse the full baby clothes collection or our kids clothes range for sizes beyond the newborn stage.
Shipping costs $7.95 in Australia, with free shipping available on orders over $97. A 30-day return and exchange policy is offered.
Sources
- National Maternity Data Development Project: Baby head circumference—Research brief no. 3 (AIHW)
- Dressing a newborn — Pregnancy, Birth and Baby
- Growth – birth to 18 years (CAHS WA)
FAQ
Is size 0000 the same as 3 months?
No, 0000 usually refers to newborn sizing, while 000 typically covers 0 to 3 months. Many brands overlap the two, so check your baby’s current length and weight against the specific brand’s chart rather than assuming by age.
Is size 6-12 months the same as size 0?
No, “0” is not a standard part of the 6 to 12 month range in the common Australian sizing system, which runs 0000, 000, 00, then into 6 to 12 months labelling. Match your baby’s measurements to the brand’s own chart, since 6 to 12 months covers a wide span.
Is 57 centimetres long for a newborn?
It is on the longer side but within a normal range, since full-term newborn length varies noticeably between babies. Weight and head circumference, alongside length, give a fuller picture, and a baby that long may fit 000 sooner than 0000, according to AIHW’s growth data.
What is the average size of a newborn baby in Australia?
There is no single official average figure published for Australian newborns specifically, though health guidance places typical head circumference at birth between 33 and 37 centimetres, according to AIHW. Weight and length vary enough between babies that measuring your own baby matters more than any single average.
How many baby clothes should I buy per size?
Buy only a handful of pieces per size, since babies move through newborn and 0 to 3 month sizing quickly, as recommended by Pregnancy, Birth and Baby. A small capsule of bodysuits and rompers per size, backed by easy returns, beats a full wardrobe you might outgrow before it is worn.
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