Sizing & fit
US baby sizes explained: 3M, 6M, 9M and 12M vs 0–3 months
What single-number US labels usually mean, why a US 6M is not the same as 6–12 months, and how to convert US baby sizes to the 0–3M to 18–24M sizes we use.
Two styles of US label
Baby clothes made for the US market use two styles of size label, sometimes from the same shop. Some use ranges, like ours: 0–3M, 3–6M, 6–9M and 9–12M. Others use a single number: 3M, 6M, 9M, 12M, 18M and 24M. At the small end you may also see Preemie and Newborn, often shortened to NB.
Ranges are easy to read. The single numbers are where confusion starts, especially for families in Pakistan who are used to month ranges, or relatives in the US buying for a baby here.
What a single number usually means
In most cases, a single number on a US label means “up to” that age. So a 6M label usually fits roughly the same baby as a 3–6M range, a 9M fits 6–9 months, and a 12M fits 9–12 months. It does not mean the piece is for a six-month-old and upwards, which is the mistake that leads to US 6M clothes being too small for a baby who has just turned six months.
This isn’t universal: US brands vary, and not every brand uses the number the same way or cuts to the same measurements. That is why the height and weight on each brand’s own chart, or printed on the label, which many US labels include in inches and pounds, are more reliable than the number itself.
US sizes against the sizes we use
These are approximate. Always compare the baby’s actual length and weight with each brand’s own chart or the measurements on the label, and with our size guide.
- Preemie and Newborn (NB): smaller than our first size. Our smallest is 0–3M, made for babies of about 56–62 cm and 4–6 kg.
- US 0–3M or 3M: our 0–3M.
- US 3–6M or 6M: our 3–6M, made for about 62–68 cm and 6–8 kg.
- US 6–9M, 9M, 9–12M and 12M: together, roughly our 6–12M, which covers the whole second half of the first year.
- US 12–18M or 18M: roughly our 12–18M.
- US 18–24M or 24M: roughly our 18–24M.
- US 2T: a toddler cut for about the same age as 24M, with a little more length.
Why our 6–12M covers two US sizes
Our sizes use a single 6–12M size for the second half of the first year, about 68–80 cm and 8–10 kg. US ranges split that half-year into two, 6–9M and 9–12M. So a baby who wears US 9M may be at the start of our 6–12M, while a baby in US 12M may be at the top of it. If you are converting from US sizes, look at which half of 6–12M the baby is in, and choose 12–18M instead if they are already in US 12M and growing.
Buying from Pakistan for a baby in the US
If you are sending a gift to a baby in the US, ask the parents for the size they wear and, if possible, their length and weight in whatever units they use. Convert using the list above, then go one size up for a gift that should fit for a while. We deliver internationally; the charge and timing for your country are confirmed with your order. Our delivery and returns page covers international orders, and you can browse our baby range with the size already chosen.
For the other systems you are likely to meet, see our baby size conversion chart.
Quick answers
Is a US 6M the same as 6–12 months?
No. A US 6M label usually means up to six months, so it is closer to a 3–6M size. A baby who has just turned six months often needs the next size.
What does NB mean on baby clothes?
NB means Newborn, a US size smaller than 0–3M for babies in their first weeks. Our smallest size is 0–3M.
What size is US 12M in your sizes?
Roughly the top of our 6–12M. If the baby is already comfortable in US 12M and still growing, choose our 12–18M.
Why do US baby clothes list pounds and inches?
Because many US labels give the baby’s weight and height range under the size. They are the most reliable part of the label, and converting them to kilograms and centimetres lets you compare with any size chart.