How To Tell What Size Tool Box Will Fit Your Pickup Truck
There’sa lot more to truck bed tool boxesthan simply having a built-in place to store your tools — though that is their primary function. You need to think about cost, durability, and construction, as well as how exactly you plan to use it, how much weight it adds,who makes it, etc. Though arguably the most important consideration is the dimensions because your truck bed tool box won’t be of much use if it doesn’t actually fit in said truck bed properly. Fortunately all you really need to figure those measurements out is a tape measure.
As truck box manufacturerUWSpoints out, there are a lot of measurements that need to be taken to verify the tool box you buy isn’t too big to fit or too small to stay in place. Additionally, you might need to make additional checks if your pickup bed is a little more compact — otherwise those wheel wells could get in the way and you’ll be left with a tool box you’re able to’t actually put in your truck.

Measure twice, buy once
Obviously you’ll need to figure out the right dimensions, but the trick is knowing exactly what areas you’ll need to measure.
If the bed is small enough that the wheel wells don’t allow enough room, you’re able to look into getting an angled tool box that tapers inward to allow for better clearance.

Measure more if you’re towing stuff
There’s a bit more you need to account for if you use (or plan to use) your pickup truck for towing with an in-bed hitch — either fifth wheel or gooseneck. If you don’t plan on towing or expect to use a trailer hitch (mounts under the bumper) then you don’t need to bother with this bit.
If you have less than six inches of clearance, look for a tool box with a narrower side depth.