Is it time to replace your race suit? Let’s get you track-ready. Kart underwear is sized on your body, the same chest and waist measurements as a kart suit. The complication is that this category uses four different labelling systems, sometimes within the same brand.
| System | Sizes | Which products |
|---|---|---|
| Single letters | S, M, L, XL, XXL | OMP Padded Shorts, Alpinestars Tech KX, Sparco B-Rookie |
| Paired letters | XS-S, M-L, XL-XXL | The OMP KS range, Alpinestars Ride Tech |
| Wide pairs | S/M, L/XL, XXL/XXXL | OMP KS Winter-R tops and long johns |
| One size | no choice | All the balaclavas: OMP KS, Sparco Rookie and Softknit, Alpinestars Ride Tech |
Measure these
Charts
SparcoLetters follow their body ladder.▼
| Letter | Suit size | Chest (cm) | Waist (cm) |
|---|---|---|---|
| XS | 44 / 46 | 86 – 93 | 74 – 81 |
| S | 48 / 50 | 94 – 101 | 82 – 87 |
| M | 52 / 54 | 102 – 109 | 88 – 97 |
| L | 56 / 58 | 110 – 117 | 98 – 105 |
| XL | 60 / 62 | 118 – 125 | 106 – 113 |
| XXL | 64 / 66 | 126 – 133 | 114 – 121 |
Sparco publish no separate underwear chart. These are the bands from their own body size chart, which is what their letters follow. The K-Carbon tops run XXS, XS-S, M-L and XL, so the middle two each cover two of these rows.
AlpinestarsXS to XL published, from their tech layer range.▼
| Letter | Chest (cm) | Waist (cm) |
|---|---|---|
| XS | 86 – 90 | 72 – 76 |
| S | 90 – 94 | 76 – 80 |
| M | 94 – 98 | 80 – 84 |
| L | 102 – 106 | 88 – 92 |
| XL | 106 – 110 | 92 – 96 |
Their own chart jumps from 98 cm to 102 cm between M and L, so a 98 to 102 cm chest falls in a gap. Ring us if that is you.
OMPSold in letters and pairs with no published measurements.▼
OMP put a size chart on every kart suit, boot and glove product page but not on their underwear. Rather than convert from another brand’s chart, size the KS range from your OMP kart suit size, or send us your chest and waist and we will confirm before it ships.
The KS Winter-R tops and long johns use unusually wide pairs, S/M, L/XL and XXL/XXXL, so each garment covers three suit sizes. If you are on a boundary there, take the larger.
Socks
OMP sell the KS sock in S, M and L against shoe size rather than clothing size.
| Size | UK shoe | EU shoe |
|---|---|---|
| S | UK 6.5 – 7 | EU 40 – 41 |
| M | UK 8 – 9 | EU 42 – 43 |
| L | UK 9.5 – 10.5 | EU 44 – 45 |
OMP publish the shoe ranges for their racing socks and the KS kart sock follows the same ladder. Kart socks are thicker than everyday ones, so if you are buying boots at the same time try them together or allow for it.
Balaclavas
Every kart balaclava we stock is one size and stretches to fit, including the OMP KS and KS Summer, the Sparco Rookie and Softknit, and the Alpinestars Ride Tech V2. There is nothing to choose. If you wear glasses, an open face style is easier to get on without dragging the arms out of place.
What this layer is for
Everything in this category is marked Non-FIA, and that is normal. Kart underwear is a comfort, wicking and abrasion layer rather than fire kit, which is the opposite of car racing underwear. What it does do is stop the suit chafing over a long day, keep you warm in winter, and add padding at the ribs where the seat works on you.
The padded shorts are the ones people underestimate. They sit between you and the seat and they are the difference between finishing a wet club meeting comfortable and finishing it bruised.
Sparco bands from sparco-official.com. Alpinestars from the size guide on their Race V3 Top Tech Layer. Sock ladder from OMP’s published racing sock ranges. OMP publish no kart underwear measurements, which is why they are not tabulated. All checked 2 August 2026.
