The adult chart stops at US 3. This one extends the same scale downward, with the measuring and safety points that only apply to children.
Enter a measurement in millimetres; readings below the adult range will be flagged.
Your size
The standard adult chart starts at US size 3. Children's fingers are smaller than that, which is why looking up a child's size on an adult chart usually produces nothing useful.
The table below extends the same scale downward. It is derived from the adult figures using the same increment — about 0.4 mm of inside diameter per half size — so the two charts meet exactly at US 3 rather than disagreeing at the boundary.
| US size | Inside diameter | Inside circumference | Rough age guide |
|---|---|---|---|
| 0 | 11.7 mm | 36.8 mm | Infant, typically under 12 months |
| 0.5 | 12.1 mm | 38.0 mm | — |
| 1 | 12.5 mm | 39.3 mm | Toddler, roughly 1 to 3 years |
| 1.5 | 12.9 mm | 40.5 mm | — |
| 2 | 13.3 mm | 41.8 mm | Roughly 4 to 7 years |
| 2.5 | 13.7 mm | 43.0 mm | — |
| 3 | 14.1 mm | 44.2 mm | Smallest standard adult size |
Children's finger sizes vary enormously at any given age, far more than adults' do. The age guide above is a rough starting point for narrowing a range, not a substitute for measuring. If you are buying for a specific child, measure the specific child.
The methods are the same as for an adult, but small fingers magnify small errors. A half size here is still about 1.25 mm of circumference, which is a larger proportion of a child's finger than of yours.
This is the part adult sizing guidance does not cover, and it changes the decision.
Rings are a choking hazard for babies and toddlers, and a small ring can trap a finger if it is left on while the child grows. Jewellery intended as a keepsake for an infant is normally best kept rather than worn. If a ring is worn, check the fit regularly rather than assuming it still fits.
Below UK size A the British letter scale does not extend in normal retail use, which is why the table above shows millimetres rather than a letter for the smallest sizes. Quoting a letter that jewellers do not stock would be worse than quoting none.
For European sizing there is no such problem: the ISO size is simply the inside circumference in millimetres, so the circumference column above is already the EU size. How EU sizing works
Once a child's finger reaches US 3, the full adult chart takes over.
The millimetre figures are consistent and checked, but the size labels attached to them are convention rather than enforced standard. Published charts vary between manufacturers by up to roughly a quarter of a size. When precision matters, quote the inside circumference in millimetres and use the retailer's own chart rather than a general one.
It depends entirely on the child. Infants are roughly US 0, toddlers around US 1, and children of four to seven often around US 2, but finger size varies enormously at any age. Measure rather than assume — the ranges are only useful for narrowing down a starting point.
US 3 is the smallest size on the standard adult chart, at 14.1 mm inside diameter and 44.2 mm circumference. Sizes below that exist for children and run down to around US 0, at roughly 11.7 mm diameter.
Use a paper strip about 3 mm wide rather than the usual 5 mm, wrap it loosely at the base of the finger, and check it also clears the knuckle. Measuring a ring the child already wears is easier and more reliable than measuring the finger directly.
Only slightly. A ring loose enough to spin freely will come off and be lost, and on a small finger the margin between snug and too loose is narrow. A plain band that can be resized later is a better plan than deliberate oversizing.
Only partly. The British letter scale begins at A, which is around 37.8 mm circumference, so the smallest children's sizes fall below it. For those, quote the inside diameter or circumference in millimetres instead, which any jeweller can work from.
Takes over from US 3 upward, with UK and EU equivalents.
Measuring a fingerThe strip method, adapted above for small fingers.
Resizing as they growWhy a plain band is the sensible choice for a child.
Sizing a gift discreetlyBorrowing a ring to measure, without spoiling the surprise.