Truck Door Decal Size: Choosing 12, 18 or 24 Inches

Truck door decal size comes down to two things: how much flat space your door has, and how well the lettering reads from a distance. Work Decals offers three widths, 12, 18 and 24 inches. Measure the flat area first, tape out each width, and step back to look. Then use the builder preview to confirm the lines you plan to include.

Widths, not legal sizes

The numbers 12, 18 and 24 describe how wide the decal is. They are not a federal size requirement. The marking rule, 49 CFR 390.21, does not set a letter height in inches. It asks for your name and USDOT number on both sides, in letters that contrast sharply with the background and can be read from 50 feet in daylight while the vehicle is stopped.

So the real test is the 50-foot look, not a number on a spec sheet. Our guide on how big USDOT numbers need to be goes deeper, and the USDOT number display rules page has the summary. Rules differ in some states, so check with FMCSA or your state.

Step 1: Measure the flat area

Stand at the door and look for the largest stretch that is flat, clean and free of obstacles. Skip these:

• door seams and panel gaps
• the handle and its recess
• window trim and the edge of the glass
• rivet lines, ribs and raised body lines
• curves where the panel bends

A decal that crosses a seam or a deep crease may not lie flat. Measure the width and height of the clear area with a tape, then leave some breathing room between the decal and any edge.

Mark the spot with masking tape, as the installation tips suggest, and check that it is level.

Step 2: Count your lines

The builder takes up to six lines: company name, city, USDOT, MC and two extra lines such as a CA number or GVW. Each line adds height to the rectangle. A long line also matters, because every line has to fit across the width. A long company name on a 12 inch decal ends up with smaller letters than a short name does.

Watch the preview as you type. If the stack looks crowded, you have three choices: drop an optional line, shorten the text, or move up to the next width.

Step 3: Test the width at distance

A wider decal gives you larger lettering, and larger lettering is easier to read from farther away. We do not publish a chart that ties each width to a reading distance, because it depends on your lines, your colors and how clean the door is.

Test it instead:

1. Cut paper or cardboard to 12, 18 and 24 inches wide.
2. Write your lines on it in bold capitals, in the colors you plan to use.
3. Tape it to the door at the marked spot.
4. Walk 50 feet away in daylight and read it.

If you can read your name and number comfortably, that width works. If you squint, go wider.

Step 4: Compare the price of each width

It depends where you order. On a product page, such as the USDOT + MC two-line decal, the listed price is the same at 12, 18 or 24 inch width, so pick the width that reads clearly on your door. In the door builder, width adds a fixed amount per decal: $0 for 12 inch, $6 for 18 inch and $14 for 24 inch. The builder total for the same two-line layout, which starts at $16.99 at 12 inch, works out like this:

• 12 inch: $16.99 per decal, $33.98 for two doors
• 18 inch: $22.99 per decal, $45.98 for two doors
• 24 inch: $30.99 per decal, $61.98 for two doors

Both routes make the same kind of decal. For the full builder price list, see truck lettering cost.

Using the builder preview

In the door builder, choose a width, then switch the door color to match your truck. The door color is only a picture. The preview is a generic door, not a drawing of your exact truck, so use it to judge proportions and color, then confirm with the tape on the real door.

The builder also flags lettering and sticker colors that are too close together. Our guide to truck lettering fonts and colors explains which pairings read clearly.

A tractor cab door, a compact pickup door, a van and a box truck side are all different. Measure yours instead of assuming. If you want name, city and numbers on one decal, look at the Custom USDOT Logo. For a short USDOT and MC stack, see the USDOT + MC Two-Line Decal. For free text such as a phone number, try the Make-Your-Own 5-Line.