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What Are the Measurements of a Stop Sign?

Usually seen at roadway intersections, stop signs are bright red traffic signs that alert drivers to stop their cars. The driver must then look in all directions and determine that there is no oncoming traffic before proceeding across the intersection. Stop signs are a standard form of traffic sign and are generally made to specific measurements.

Standard Sizes and Shapes
- The standard size of a stop sign measures at 30 inches across an octogon shape. There is a white border of 20 mm (or a little less than an inch) around the sign. While the octogon is the most recognized shape, used by most other countries around the world, some regions, such as Zimbabwe and Japan, opt to to use a circular or triangular stop sign.
Required Height
- According to the Manual on Uniform Traffic Control Devices for Streets and Highways, first published in 1935, the height of a stop sign must be at least 7 feet in urban areas and 5 feet in rural areas. The height of a stop sign was mandated to ensure that drivers would have good visibility of it when coming to an intersection that required them to stop.
Larger Sign Specs
- For larger expressways and multilane roads, signs measuring 35 inches, with an 11-inch legend and a 1-inch border, are used to ensure that the multitudes of drivers see the sign. In addition to the size specifications of a larger stop sign, the field, letters and border of the sign are retroreflective to ensure it is easier to see at night as well.
Sign Legend
- The legend on the stop sign, which in the United States simply consists of the letters S-T-O-P, measures 10 inches in height. The English letters on the sign are used in the UN Convention on Road Signs and Signals, adopted as such because the sign was originated in the United States, before its use was widespread among other countries around the world.
Material Thickness
- When it comes to the measurements of stop sign materials, those specs are dictated by the type of material used to make the sign. Stop signs are made of three main material types:
  
  • Engineer Grade Reflective Sheeting/.80 Aluminum: A reflective material that shines brightly during the nighttime hours, this material will never rust and lasts for about seven years.
  
  • High Intensity Reflective Sheeting/.80 Aluminum: This material reflects when light hits it and is actually up to 10 times more reflective than engineer grade, with a thickness of .8 inches and longevity of 10 years.
  
  • Prismatic Reflective Sheeting/.80 Aluminum: This material is extremely bright in darkness, with a .8 inch thickness that has flourescent sheeting on the surface. This material also does not rust and lasts upward of seven years.