Diameter
Delta Scientific puts standard bollards at 4 to 6 in across, measured at the core without decorative sleeves, with the largest at 12 in or more for heavy, high-speed traffic. Steel pipe bollards are sold by pipe size, so a “6 in” bollard is usually 6 in nominal pipe (about 6⅝ in outside), which is why covers are sold to fit specific outside diameters.
| Diameter | Typical use |
|---|---|
| 4 to 4½ in | Marking edges, sidewalks, light knocks; the common removable size |
| 6 in | The everyday impact bollard: storefronts, gas meters, building corners, docks |
| 8 in and up | Truck traffic, loading areas; crash-rated bodies are often in this range |
Height
Most bollards stand 36 to 42 in above grade, within an overall range of about 30 to 44 in, with taller posts for high-risk areas (Delta Scientific). TrafficGuard’s install guide sets surface-mounted fixed bollards at about 36 in above the finished surface. Taller posts are easier to see from a pickup or a forklift.
Below the ground
An embedded bollard has as much going on below grade as above it. How deep it goes and how big the footing is depends on the mounting and the load: see core-drilled and embedded installation, and for crash-rated systems, the manufacturer’s tested foundation on the crash ratings page.