USDOT number decal requirements
If your vehicle must be marked under FMCSA rules, both sides must show your legal name or single trade name and your USDOT number ("USDOT 1234567"), in a color that contrasts sharply with the background and is readable in daylight from 50 feet while parked.
What the rule says
The marking rule is 49 CFR 390.21T (the earlier section 390.21 is suspended). For self-propelled commercial motor vehicles subject to it, the marking must show:
- The legal name or a single trade name of the motor carrier
- The number FMCSA issued to the carrier, preceded by the letters "USDOT"
And it must:
- Appear on both sides of the vehicle
- Be in letters that contrast sharply in color with the background
- Be readily legible during daylight from 50 feet (15.24 m) while the vehicle is stationary
- Be kept in a condition that stays legible
Practical sizing tips
The rule sets legibility, not a letter size. In practice, 2 to 3 inch tall letters in a bold, plain font are what most shops use to stay readable at 50 feet. White on a dark door or black on a white van both work; avoid thin script fonts and low-contrast colors.
Not sure if your vehicle needs a USDOT number at all? Check FMCSA's registration rules or ask your insurer. This page explains the marking, not who must register, and is not legal advice.
Decal or magnet?
- Cut vinyl lettering: permanent, clean look, the most common choice
- Door magnets: easy to remove for personal use, but they must stay on and readable while operating
We cut USDOT and MC numbers in vinyl in Brooklyn, often same day, and can install them on both doors.
Questions
Where do USDOT numbers go on a truck?
On both sides of the vehicle, usually the driver and passenger doors.
How big do USDOT letters have to be?
The rule requires them to be readable from 50 feet in daylight; it does not set a fixed size. Most shops use letters about 2 to 3 inches tall.
Can I use my business name instead of my legal name?
The rule allows the legal name or a single trade name of the motor carrier.
Sources: eCFR: 49 CFR 390.21T Marking of self-propelled CMVs · eCFR: 49 CFR 390.21 (suspended)
