A skateboard has one size that matters, and it is not the length. Decks are sold by width, in inches, because width is what your feet actually stand on and what decides whether the board flips easily or lands stably. Length and wheelbase come along for the ride. Pick a width and everything else on the board, trucks and wheels included, follows from it.
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Width, not length
Ask most shops what size board you need and they will answer in inches of width: 7.75, 8.0, 8.25. That is the whole spec. An 8.0 inch deck is the single most common board sold, and it suits an adult of average foot size skating a bit of everything.
The trade-off is simple in both directions. Narrower boards are lighter and rotate faster, which is why street and technical skaters ride them. Wider boards give you more surface to land on and feel steadier at speed, which is why park, transition and vert skaters ride them. Neither is correct in the abstract; they are correct for what you are trying to do.
The method
street and technical −0.25 in · all-around 0 · park and transition +0.25 in · cruising +0.5 in
then rounded to the nearest 1/8 in, the increment decks are actually sold in
Shoe size is a rough proxy for how much boot has to fit between the edges. The line is anchored at both ends of the real range: a men's US 10 on an 8.0 inch deck, the most common board sold, and a kids US 13 shoe on a 7.0 inch mini, which is about right for a seven year old. Women's and kids sizes convert to a men's equivalent on the Brannock scale, the same one our shoe size converter uses, so the pages agree.
Worked example
Deck width by shoe size
Men's US shoe on the left. Decks come in eighth of an inch steps, which are coarser than shoe sizes, so neighbouring sizes sometimes land on the same board. That is the chart being honest rather than vague.
| Men's US shoe | All-around deck | Street | Park |
|---|---|---|---|
| 5 | 7.5 in | 7.25 in | 7.75 in |
| 6 | 7.625 in | 7.375 in | 7.875 in |
| 7 | 7.75 in | 7.5 in | 8.0 in |
| 8 | 7.75 in | 7.5 in | 8.0 in |
| 9 | 7.875 in | 7.625 in | 8.125 in |
| 10 | 8.0 in | 7.75 in | 8.25 in |
| 11 | 8.125 in | 7.875 in | 8.375 in |
| 12 | 8.25 in | 8.0 in | 8.5 in |
| 13 | 8.25 in | 8.0 in | 8.5 in |
What size trucks for your deck
This is the question that follows every deck purchase, and it has a trap in it. The intuitive answer, match the axle width to the deck width, is wrong. An Independent 129 carries an 8.0 inch axle but is built for a 7.4 to 7.8 inch deck, because axle width is measured across the threaded ends and the wheels sit inboard of them.
What you actually want is for the wheels to sit roughly flush with the edges of the deck. Too narrow and the board feels tippy underfoot; too wide and it turns lazily and you catch a wheel on landings. Every truck brand publishes a deck-width range for each model, and that range is the number to match. Here are the common ones.
| Deck width | Independent | Thunder | Venture |
|---|---|---|---|
| Up to 7.8 in | 129 | 143 to 145 | 5.0 |
| 7.8 to 8.25 in | 139 | 145 to 147 | 5.25 |
| 8.25 to 8.5 in | 144 | 148 to 149 | 5.6 |
| 8.5 to 8.75 in | 149 | 151 | 5.8 |
| 8.75 to 9.25 in | 159 | 161 | 6.1 |
So an 8.0 inch deck takes an Independent 139, a Thunder 145 to 147, or a Venture 5.25. An 8.25 inch deck takes the same Independent 139, since that model covers up to 8.25, though a 144 also works if you prefer the wheels sitting right at the edge. Model numbering is each brand's own, so check the deck-width range on the product page rather than assuming numbers match across brands.
Wheels
Two numbers: diameter in millimetres and hardness in durometer, written as a number followed by "a". Smaller and harder accelerates faster and slides more predictably. Bigger and softer rolls faster over rough ground and absorbs cracks.
| Riding | Diameter | Durometer |
|---|---|---|
| Street and technical | 50 to 53 mm | 99a to 101a |
| All-around | 52 to 55 mm | 99a |
| Park and transition | 54 to 58 mm | 97a to 101a |
| Cruising | 56 to 60 mm | 78a to 87a |
The cruising row is the one worth knowing about, because it is the biggest single difference in how a board feels. Soft wheels in the high 70s or 80s roll over cracked pavement and gravel that would stop hard wheels dead. They are slower to accelerate and no good for sliding, but if the board is transport rather than a trick machine, soft wheels transform it.
Buying for a kid
Decks under 7.5 inches are youth sizes: micro around 6.5 to 6.75, mini around 7.0, mid around 7.3. The temptation is to buy a full-size board for a child to grow into, and it is the single most common mistake parents make here.
A board too wide to flip and too heavy to pop means the tricks that keep a kid interested are physically out of reach, and they usually conclude they are bad at it rather than that the equipment is wrong. Buy to fit now. A deck is the cheapest part of the setup to replace, trucks and wheels move across to the next one, and a kid who lands things progresses fast enough that the board will be outgrown for happy reasons.