Speed Limit 10 MPH Sign: Sizes, Where It's Enforceable, Mounting
Updated · By the Cone to Curb editors
A speed limit 10 mph sign is the standard Speed Limit (R2-1) sign, black on white, showing 10. It's the usual limit for parking lots, private drives, campuses, marinas and mobile home parks. The common size is 24 x 30 inches, with 18 x 24 the smallest the MUTCD lists, and the bottom of the sign should be at least 7 feet up where people walk or park.
| Where | R2-1 size |
|---|---|
| Conventional road, single lane each way | 24 x 30 |
| Conventional road, multi-lane | 30 x 36 |
| Expressway | 36 x 48 |
| Freeway | 48 x 60 |
| Minimum | 18 x 24 |
| Oversized | 30 x 36 |
Sizes in inches, from MUTCD Table 2B-1. In a parking lot, 18 x 24 is common and 24 x 30 reads better from a moving car.
Who sets a 10 mph limit, and who enforces it
Under Section 2B.21, a Speed Limit sign shows the limit "established by law, ordinance, regulation, or as adopted by the authorized agency," and in multiples of 5 mph. That's straightforward on public streets. Off them it depends on the property:
| Property | MUTCD applies? | Who sets the limit | Enforcement |
|---|---|---|---|
| Public street | Yes | City, county or state | Police |
| Private road open to the public (campus, office park, shopping center drive) | Yes | Owner, sometimes with the city | Depends on state law and local agreements |
| Gated private road (HOA, closed to the public) | No | Owner or association | Usually the association's own rules and fines |
| Parking lot or garage, including aisles | No | Owner | Mostly the owner's rules; police rarely ticket for speed there |
State laws differ on whether police can enforce a posted limit on private property. If enforcement matters, ask the local police department or the city attorney. On private property, the sign works mostly as a clear rule people agree to when they drive in, backed by towing, warnings or HOA fines.
Why 10 and not 7 or 8
The MUTCD says speed limits are posted in multiples of 5 mph. Odd numbers like 7 or 8 show up on private property for attention, but on any road covered by the MUTCD they aren't allowed, and a nonstandard number doesn't make drivers slower than a well-placed 10.
Mounting
- At least 7 feet to the bottom of the sign where people park, bike or walk, and on sidewalks; 5 feet in rural areas (Section 2A.15).
- At every entrance, and again after long stretches or turns where drivers forget.
- A plaque mounted below can sit 1 foot lower.
Add-ons that help
- A speed feedback display below the sign. On roads covered by the MUTCD, the display shows a steady number and doesn't flash. See solar powered radar speed signs.
- Speed bumps in lots, where 10 mph is still too fast near doors and crosswalks. See plastic speed bumps.
- Pavement legends such as SLOW or 10 MPH painted at entrances.
Mistakes we see
- "SPEED LIMIT 7". Not a standard limit on any MUTCD road.
- Signs at bumper height. Parked cars and snowbanks hide them.
- One sign at the main entrance only. Drivers who use the back entrance never see it.
What it costs
Ballpark U.S. prices in late 2026: $25 to $60 for an 18 x 24 aluminum R2-1 with reflective sheeting, $35 to $80 for 24 x 30, and $30 to $80 for a post and hardware.
Where to buy
Sign shops, parking lot suppliers and safety sign sellers. Ask for the size, the sheeting type and the aluminum thickness.