How to Measure Your Truck Bed for a Tool Box

Truck tool boxes and transfer tanks can add extra utility and function to your pickup truck. However, getting the wrong size tool box or transfer tank can be quite frustrating — imagine getting your new tool box and then realizing that it doesn't fit your truck bed or interferes with your 5th wheel setup.

It happens more often than you’d think. 
 
That's why we've put together this step-by-step guide for measuring your truck bed before you make your purchase. Trust us — you don't want to put the cart before the horse on this one. Get the correct tool box or transfer tank for your truck the first time around by following this guide that takes you step-by-step through the process of measuring your truck bed correctly to ensure your new tool box will be a perfect fit and a longtime addition. 
 
Follow along below in the step-by-step process of getting the correct measurements of your truck bed and choosing the right UWS tool box for your truck.

Before we get started, you will need to understand these key definitions and details.

What's a truck bulkhead? A truck bulkhead is the wall within the truck bed that is closest to the cab. This wall, or bulkhead, prevents cargo from colliding with the cab. This will be an important detail when measuring to get the correct size tool or transfer tank. 

 
Short-bed vs. long-bed trucks: Short-bed trucks have shorter beds and often times the wheel well is closer to the bulkhead. This reduces the length and width of the boxes and tanks that can fit in the bed of the truck, especially if a 5th wheel hitch is installed or a gooseneck trailer is being towed. The short-bed truck has less cubic footage and for this reason, ensuring a truck bed tool box or transfer tank has sufficient space is important.  
 
Wheel well clearance: This is the space between the wheel wells inside the truck bed. Be sure the wheel wells are wider than the tool box or transfer tank, especially on short-bed trucks. Similarly, make sure the length of the tool box, from the left side to the right side, is not too long, or it may not fit between the wheel wells. Angled tool boxes and shallow or narrow tool boxes are good options and are designed to fit around the wheel wells on short cab truck beds more easily. Be sure to properly measure your truck bed.  
 
Tool box length: Make sure the tool box length is close to the exterior bed rail width, but not larger or smaller. In order for your tool box to be securely mounted and installed, each side will need to have at least 1.5" of the tool box resting on the truck bed rails. Likewise, you will also need a 1" gap between the bed rails and the tool box body in order for the J-hooks to fit correctly. See below for more information. 
 
Tool box body length: Make sure the tool box body length is smaller than the interior bed rail width, or the tool box will not fit in the truck bed. See below for more information. 
 
Transfer tank bracket clearance: Make sure the brackets have at least 6" of space from the 5th wheel hitch rails or the gooseneck ball hole. See below for more information. 

You can do this by measuring the width of the truck bed from the outside edges of the truck bed rails, nearest the truck cab. This means you will measure the widest point of the exterior of the truck bed, to the outside edge of the rails where the tool box will be mounted. 

 
This will give you the width of the bed frame rails. Make sure that your tape measure is not sagging when making this measurement to ensure a correct reading and write down this number and note as "exterior bed rail width."   
 
In the example above, the distance from A to B is 72.75".  

Do this by measuring the width of the truck bed from the inside edges of the truck bed rails. This means you will measure the narrowest point of the interior of the truck bed rails.  
 
This will give you the width of the interior bed frame rails. Make sure that your tape measure is not sagging when making this measurement to ensure a correct reading and write down this number and notate as "interior bed rail width." 
 
In the example above, the distance from C to D is 65". 

For transfer tank fitment, this step is critical.

Next, you will measure the space in between the wheel wells inside the truck bed. This number will give you the width of the interior of the truck bed which you will compare to the crossover tool box or transfer tank width later. 
 
Be sure to write down this number and note as "wheel well width." This step is crucial for transfer tank and crossover tool box fitment. 
 
In the example above, the distance from E to F is 51".

Next, measure your truck bed from the upper lip of the truck bed rail to the bottom of the bed deck. This means you are measuring the depth of the truck bed. This measurement will help you to know the bed depth your truck has so that your tool box can maximize space effectively without being too deep. 
 
This is important — a tool box too deep will not fit inside the bed, and a tool box too shallow will not maximize storage space. Measure from the lip of the bed rail, G, to the floor of the bed, H. Make sure your tape measure is straight and record this measurement as "vertical bed depth."  

In the example above, the distance from G to H is 19.25". 

This will help to ensure that the tool box you choose will not interfere with the wheel wells in the truck bed. Start by placing the end of the tape measure at the bulkhead on the lip of the truck bed itself, near the bed rail, and measure rearwards towards where the wheel well begins.  
 
Your tape measure should be hovering over the truck bed, running alongside the bed rail.
 
Looking over the tape measure and down towards the wheel well, look for where the wheel well hump begins and take your measurement to note how much space there is between the bulkhead and where the wheel well begins. Place a piece of tape on the bed rail at this measurement.

Be sure to write down this number and note as "distance to wheel well".

In the example above, the distance from I to K is 20".  The piece of tape is placed on the bed rail at the 20" mark.

This step is essential for trucks equipped with 5th wheel or gooseneck hitches. 

Finally, if you plan to tow and have 5th wheel frame rails or a gooseneck ball in the bed of your truck, you will measure from the outside lip of the bed bulkhead — that's the lip of the wall of the bed closest to the truck cab.  
 
This measurement is important as you will need to ensure that your tool box or transfer tank does not interfere with your trailer hitch when towing. This is especially important in short-cab trucks.  
 
In order to measure correctly, grab a lengthy 2x4, a pole or a long straight edge of any kind. Place it over the 5th wheel rail closest to the truck cab or on the outer edge of the gooseneck ball hole, on the side closest to the truck cab, allowing it to span across the bed rails. 
 
Following the bed rails, measure all the way from the truck cab to the 2x4 or straight edge, which should be placed over the forwardmost 5th wheel rail or the forwardmost edge of the gooseneck ball hole. 
 
This measurement will give you the distance from the truck cab to the front 5th wheel rail or gooseneck ball hole. Make sure your tape measure is straight and not sagging when taking the measurement.  
 
This measurement will be notated as "length from bulkhead to hitch."  Record this number. 
 
In the example above, the distance, from I to J, to the gooseneck ball hitch is 37.25".

Once you have finished measuring and recording the numbers, measure once again to ensure the correct measurements were made.  
  
Your numbers should look like the example below. (Note: these numbers are used for example only.) 
 

• Measurement 1: Exterior bed rail width — 72.75"
• Measurement 2: Interior bed rail width — 65"
• Measurement 3: Wheel well width — 51"  (for transfer tanks only)
• Measurement 4: Vertical bed depth — 19.25"
• Measurement 5: Distance from bulkhead to wheel well — 20"
• Measurement 6:  Wheel well depth — 14"
• Measurement 7: Length from bulkhead to gooseneck ball hitch — 37.25"  (for towing applications only)

Find one of the many UWS truck tool boxes or transfer tanks available on the UWS website and locate the dimensions. Using the example above, compare the truck bed measurements taken with the tool box dimensions.

Follow along below for a step-by-step explanation of how to calculate fitment to make sure that your chosen tool box or transfer tank fits within your truck bed.  

Use the recorded measurements taken from the previous step above and follow along below: 

Step 1: Make sure the top of the tool box is not too small. The tool box lid must sit at least 1.5" on each bed rail.

To get this measurement, subtract the tool box lid length from the interior bed rail width.

In the example above: 72.875" – 65" =  7.875". 

The final number should be at least 3" or greater, or the tool box will not fit properly. In this example, the final number is 7.875" so the tool box will fit.

 
Step 2: Make sure the interior bed rail width is greater than the tool box body width. 

In this example, the interior bed rail width measured 65" and the tool box body length measured 62". 

In this example: 65" – 62" = 3".

The tool box body length should be at least 2" smaller than the interior bed rail width. In this example, the tool box will fit.

 
Step 3. Make sure the vertical bed depth is greater than the tool box body depth.  

In this example, the vertical bed depth measured 19.25" and the tool box body depth measured 11.75".

In this example: 19.25" – 11.75" = 7.5". 

The vertical bed depth should be at least 1"– 2" greater than the toox box bed depth. In this example, the tool box will fit.

Once you've done the work and taken the measurements to ensure the truck tool box or transfer tank you like will fit your truck bed, it's safe to make your purchase and then install your new product.

UWS offers a large variety of truck tool boxes and truck transfer tanks, so take your time when considering a tool box for truck or transfer tank for truck to ensure that it fits your needs and requirements.  
 
From our crossover tool boxes and transfer tanks, to our utility chest boxes and side-mount tool boxes, UWS has many truck tool boxes and truck transfer tank options for your truck. UWS tool boxes are designed and proudly assembled in the USA, and are made to last using the highest quality parts and materials.