School uniform sizes explained
A “size 30” sweatshirt is a 30 inch chest. School uniform is often sold by measurement in inches instead of age.
Checked against UK retailer charts on 18 October 2026.
Uniform sizes by age
| Item | 3/4 yrs | 5/6 yrs | 7/8 yrs | 9/10 yrs | 11/12 yrs | 13/14 yrs |
|---|---|---|---|---|---|---|
| Sweatshirts, cardigans, polo shirts, PE T-shirts, blouses (chest) | 24" | 26" | 28" | 30" | 32" | 34" |
| Knitwear (chest) | 26" | 28" | 30" | 32" | 34" | 36" |
| Boys’ blazers (chest) | – | – | 28" | 30" | 32" | 34" |
| Girls’ blazers (ladies’ size) | – | – | 6 | 8 | 10 | 12 |
| Boys’ shirts (collar) | 11½ | 12 | 12½ | 13 | 13½ | 14 |
| Trousers and skirts (waist) | 20" | 22" | 24" | 26" | 28" | 30" |
| Boys’ school shorts (waist) | 21½" | 22½" | 24½" | 26½" | 28" | 30" |
| Jog bottoms (waist) | 18" | 20" | 22" | 24" | 26" | 28" |
These are "to fit" sizes: a 26″ chest garment is made for a child with a 26″ chest. Your School Uniform says to order a bigger size only if you're deliberately allowing room to grow.
What is a size 30 in school uniform?
A size 30 sweatshirt, polo or cardigan is for a 30 inch chest (76 cm), which this chart puts at about 9/10 years. A size 30 in trousers or skirts means a 30 inch waist, which is 13/14 years on the same chart. So always check whether a number is a chest or a waist size.
| Chest size | In cm | Usual age band |
|---|---|---|
| 24" | 61 cm | 3/4 yrs |
| 26" | 66 cm | 5/6 yrs |
| 28" | 71 cm | 7/8 yrs |
| 30" | 76 cm | 9/10 yrs |
| 32" | 81 cm | 11/12 yrs |
| 34" | 86 cm | 13/14 yrs |
How to measure for uniform
- Chest: under the arms, around the fullest part, over a T-shirt.
- Waist: where they wear their trousers or skirt, not pulled tight.
- Collar: around the base of the neck, with a finger's room.
Measuring a garment that already fits? Lay a jumper flat and measure armpit to armpit, then double it. Your School Uniform notes that ribbed waistbands stretch more than the body of the jumper.
Buying for September
Searches for uniform sizes peak every August. If you're buying early in summer, measure again in late August before term starts, as children can grow over the holidays. Height tables for everyday clothes are in kids’ clothes sizes by height.
Questions
What age is a size 28 school jumper?
A 28″ chest is about 7/8 years on Your School Uniform’s chart.
What age is size 32 in school uniform?
A 32″ chest is about 11/12 years. A 32 in trousers would be a waist size.
Are school uniform sizes chest or age?
Many items are sold by chest (tops) or waist (trousers, skirts) in inches. Check the label.
Where these numbers come from
Checked 18 October 2026. Brands change their charts, so always check the size guide of the shop you're buying from.