Kart boots use exactly the same size ladders as race boots, which means the same trap applies: Sparco and OMP share one ladder and Alpinestars run their own. The same UK size is a different EU number depending on which you buy.
Measure the foot
Two minutes with a sheet of paper beats any conversion chart, and it matters more for a kart boot than a road shoe because the sole is thin and the fit is close.
Foot length to size
Sparco and OMP both publish foot length against their sizes and never disagree by more than three millimetres.
| EU | UK | Sparco length | OMP length |
|---|---|---|---|
| 36 | 3.5 | 23.7 cm | 23.5 cm |
| 37 | 4 | 24.3 cm | 24.5 cm |
| 38 | 5 | 25.0 cm | 25.0 cm |
| 39 | 5.5 | 25.7 cm | 25.5 cm |
| 40 | 6.5 | 26.3 cm | 26.0 cm |
| 41 | 7 | 27.0 cm | 27.0 cm |
| 42 | 8 | 27.7 cm | 27.5 cm |
| 43 | 9 | 28.3 cm | 28.1 cm |
| 44 | 9.5 | 29.0 cm | 28.7 cm |
| 45 | 10.5 | 29.6 cm | 29.5 cm |
| 46 | 11 | 30.3 cm | 30.2 cm |
| 47 | 12 | 31.0 cm | 31.0 cm |
| 48 | 13 | 31.6 cm | 31.5 cm |
Alpinestars do not publish foot lengths. Use the EU column here to get into the right area, then read your UK size off the table below.
The same UK size, two different EU numbers
Alpinestars carry four half steps that Sparco and OMP do not: 40.5, 42.5, 43.5 and 45.5. From UK 7 upwards their EU numbers stop lining up with everyone else.
| UK | Sparco and OMP | Alpinestars |
|---|---|---|
| 3.5 | 36 | – |
| 4 | 37 | 37 |
| 5 | 38 | 38 |
| 5.5 | 39 | – |
| 6 | – | 39 |
| 6.5 | 40 | 40 |
| 7 | 41 | 40.5 |
| 7.5 | – | 41 |
| 8 | 42 | 42 |
| 8.5 | – | 42.5 |
| 9 | 43 | 43 |
| 9.5 | 44 | 43.5 |
| 10 | – | 44 |
| 10.5 | 45 | – |
| 11 | 46 | 45.5 |
| 12 | 47 | 47 |
| 13 | 48 | – |
A dash means that brand does not make a kart boot in that size. Order by the UK size, because it is the one we have checked against each brand’s own ladder for every product on the site.
Overshoes
The Sparco rubber and neoprene overshoes go over your kart boots rather than replacing them, so size them to your boot and not to your foot. The slip-on rubber pair are sold S to XL against a boot size, and the neoprene pair on the normal EU ladder.
How a kart boot should fit
Close, with no heel movement
Toes near the end and no sliding at the heel. A kart pedal box gives you very little room, and a boot with growing space moves on the pedal exactly when you do not want it to. Between two sizes, take the larger and let a thicker sock take up the difference.
The sole is deliberately thin
There is no cushioning, because the point is feeling the pedal through it. A kart boot that feels flat standing in the showroom is doing its job and will not soften into a walking boot.
Buying for a child
Size to the measurement today rather than to next season. A loose boot slips off the pedal, and they will have outgrown it before the extra room becomes useful.
Sparco from sparco-official.com. OMP from the size chart on their Tecnica shoe product page. Alpinestars UK labels from the UK retail convention checked against three UK retailers on 1 August 2026, which is what our listings carry. All checked 2 August 2026.
How do karting boots fit compared to normal shoe sizes?
Sparco and OMP share one sizing ladder, but Alpinestars runs its own, so the same UK size can map to a different EU number depending on the brand. Skip the conversion chart if you can and measure instead. Stand on a piece of paper with your heel against the skirting board and your weight on the foot, then measure from heel to longest toe in centimetres while wearing your kart socks.
Kart boots fit close with no heel movement and have deliberately thin soles for pedal feel, so do not expect the cushioned fit of a normal trainer. If you are between two sizes, take the larger one and let a thicker sock take up the difference. For kids, size to their foot today rather than leaving room to grow. A loose boot slips on the pedals.
