Assigned number format
Illinois assigns numbers in the pattern IL 1234 AB, using the IL prefix. The Illinois state guide illustrates the decal after the suffix.
State Requirement Summary
Illinois Boat Registration Number Requirements
Boats registered in Illinois display an IL-prefixed number such as IL 1234 AB. Illinois calls for characters 3 inches high in BLOCK letters, reading left to right on one line, must contrast sharply with background, positioned each side of the bow. Our lettering is designed to meet the displayed Illinois size and formatting requirements. The state itself issues the validation/expiration decal — we supply the registration-number lettering.
Boat number requirements
Last regulatory review: August 22, 2026
Assigned number example
IL 1234 AB
- Minimum character height
- 3 inches
- Lettering style
- BLOCK letters
- Contrast
- Must contrast sharply with background
- Spacing / separator
- Spaces between groups
- Reading direction
- Left to right on one line
- Number location
- Each side of the bow
- Validation decal
- After / aft of the registration number
- State agency
- Illinois Department of Natural Resources
What we sell vs. what the state issues: RegistrationDecals.com supplies the registration-number lettering, designed to meet the displayed Illinois size and formatting requirements. Illinois Department of Natural Resources issues the official validation/expiration decal — and any separate stickers such as aquatic-invasive-species, mussel-awareness, carbon-monoxide or lake-protection stickers, which are not interchangeable with each other.
Design your IL numbers
Starts with the Illinois format (IL 1234 AB). Tap the decal and type your own assigned number exactly as it appears on your certificate of number.
Tap the decal to edit
Decal color
We supply the registration-number lettering, sized to the displayed Illinois requirements. Illinois Department of Natural Resources issues the validation decal.
Illinois placement diagram
Both sides of the hull carry the number. The grey square marks where the state-issued validation decal goes — after / aft of the registration number.
- Height: 3 inches, block letters
- Spacing: Spaces between groups
- Location: Each side of the bow
- Validation decal: After / aft of the registration number
Diagram is illustrative. Confirm exact positioning against the instructions issued with your Illinois registration.
Official source
Illinois Department of Natural Resources — Official state publication. Last verified August 22, 2026 (source check 2026-08-22).
Illinois Department of Natural Resources — BoatingRegistration requirements can change. RegistrationDecals.com summarizes publicly available boating-registration requirements to help boat owners select and display registration numbers. Always compare your registration and decals with the current instructions issued by your state boating or registration agency before applying them to your vessel.
Illinois rules in detail
Minimum character height
Illinois specifies characters 3 inches high. Measure the character body itself — if the state excludes borders, outlines or shading, decorative trim does not count toward the minimum.
Required lettering style
BLOCK letters, reading left to right on one line. Script, italic and decorative treatments are not what this style describes.
Contrast requirement
Must contrast sharply with background. In practice that means dark characters on a light hull and light characters on a dark hull, checked in daylight from the side of the vessel.
Spacing and separator
Spaces between groups. Example: IL 1234 AB. Running the groups together with no separation does not match the stated format.
Placement on the hull
Each side of the bow. Assigned registration only.
Validation decal placement
After / aft of the registration number. The validation or expiration decal is issued by Illinois Department of Natural Resources — RegistrationDecals.com supplies the registration-number lettering only.
Common mistakes
- Ordering the number without the IL prefix or the suffix letters.
- Characters shorter than the stated minimum (3 inches) so they fit inside a narrow accent stripe.
- Using a script, italic or shadowed style instead of BLOCK letters.
- Losing the required separation between the groups — spaces between groups.
- Placing the state validation decal somewhere other than the position Illinois describes: after / aft of the registration number.
Frequently asked questions
What does a Illinois boat registration number look like?
Illinois numbers follow the pattern IL 1234 AB, using the IL prefix, a numeral group, and suffix letters.
How tall do Illinois boat registration numbers have to be?
3 inches, measured on the character itself, in BLOCK letters.
What lettering style does Illinois require?
BLOCK letters, reading left to right on one line, and must contrast sharply with background.
How much space goes between the letters and numbers in Illinois?
Spaces between groups. Example: IL 1234 AB.
Where do the numbers go on the boat in Illinois?
Each side of the bow. Assigned registration only.
Where does the Illinois validation decal go?
After / aft of the registration number. The decal itself is issued by Illinois Department of Natural Resources; we supply the registration-number lettering.
Who regulates boat registration numbers in Illinois?
Illinois Department of Natural Resources. Confirm the current instructions issued with your registration before applying anything to your hull. Last regulatory review: August 22, 2026.
Can I order Illinois boat registration numbers online?
Yes. Enter your assigned IL number in the designer on this page, pick a color that contrasts with your hull, and we cut a matched port-and-starboard pair and ship it to the 48 contiguous states.
Do I need two sets of Illinois registration numbers?
You need the number displayed on both sides of the vessel — each side of the bow — so every order ships as a matched port-and-starboard pair.
Related guides
Ready to design your IL numbers?
Our designer starts with plain block characters and proper group spacing, so you can see exactly how IL 1234 AB will read on your hull before you order.
Source: Illinois Department of Natural Resources · Official state publication · Primary · Source last checked 2026-08-22.
Registration requirements can change. RegistrationDecals.com summarizes publicly available boating-registration requirements to help boat owners select and display registration numbers. Always compare your registration and decals with the current instructions issued by your state boating or registration agency before applying them to your vessel.