I know some people had been asking about this for a while, but I thought I should do something to help (and it is a rainy day here today, so I have time).
How to...
Measure a skateboard deck (correctly)
So there have often been questions and very different measurements when it comes to skateboard deck dimensions, along with various forms or items to measure them, but I hope to help with the most simple and easy way to correctly measure your board, as per industry standards.
I have a flat metal square ruler, a standard tape measure, a soft tape measure and a tailors tape, for reference here, but the standard tape measure with the hook end is the best for an accurate measurement of length and width.
They all give the same measurements when used correctly on this Antihero eagle deck that is said to be 8.25 x 32 with 14.38 wheelbase, 6.8 nose and 6.6 tail. The one difference being these DLX 8.25 decks are often a touch wider, coming in around 8.3 or so.
The board length is often the most confused measurement, but decks should be measured from tip to tip straight across, not from the top ply layer (which will give a shorter length) and not with the concave (which will give a longer length) and most definitely not with graphic side up as that will give a super long measurement.
Note: One woodshop in particular always measured the length with the concave, so if you have a PS Stix deck it will often be shorter than listed, when compared to many other brands or other woodshop dimensions.
Width is again straight across from tip to tip, often the middle ply will sit out further than the top ply layer, but as boards can often taper, measure across in a few places, such as where the trucks are and the middle of the board too.
Wheelbase is measured from the middle of the deck bolt holes closest to each other, at each end of the board, usually anywhere from 14 to 15" but more commonly 14.25 to 14.5" apart.
Nose and tail are from the tip, same as the length in a straight line to the middle of the closest deck bolt holes, most commonly popsicle shaped decks having the nose around a quarter inch longer, but often twin boards will have the same length kicks, all up between 6.5" to 7" but quite a few are longer and many are shorter too.