Concrete Curb Calculator
Enter the length and the curb and gutter dimensions. The drawing shows the cross-section so you can check it against your plan.
Last updated November 13, 2026
How to calculate concrete for a curb and gutter
A curb is a long shape with the same cross-section all the way along. Volume = cross-section area × length.
For a curb with a gutter: area = curb depth × (curb height + flag thickness) + gutter width × flag thickness. With a 6 inch curb depth, 6 inch curb height, 18 inch gutter and 6 inch flag: 0.5 × 1.0 + 1.5 × 0.5 = 1.25 square feet.
Concrete by length for that curb
| Length | Cubic feet | Cubic yards | Cubic yards + 10% |
|---|---|---|---|
| 10 ft | 12.5 | 0.46 | 0.51 |
| 25 ft | 31.2 | 1.16 | 1.27 |
| 50 ft | 62.5 | 2.31 | 2.55 |
| 100 ft | 125.0 | 4.63 | 5.09 |
| 200 ft | 250.0 | 9.26 | 10.19 |
What the four measurements mean
- Curb depth: front to back of the raised curb.
- Curb height: how far the curb stands above the gutter.
- Gutter width: the flat pan in front of the curb.
- Flag thickness: top to bottom of the gutter pan.
Local road departments publish standard curb sections. Use those dimensions if your curb meets a public street.
Curb calculator for a plain curb, without a gutter
For a straight curb with no gutter pan, the shape is a simple rectangle: width × height × length. As an example, a curb 6 inches wide and 18 inches tall is 0.75 cubic feet per linear foot. One hundred feet of it takes 75 cubic feet, or 2.78 cubic yards. Set the gutter width to zero in the calculator, or use your own dimensions. Curb profiles are specified by the city or the site plans, so measure from those.
Frequently asked questions
How do I calculate concrete for a curb?
Find the area of the cross-section and multiply by the length. For a curb and gutter: length × (curb depth × (curb height + flag thickness) + gutter width × flag thickness).
How much concrete is in a foot of curb and gutter?
A 6 inch curb with an 18 inch gutter and a 6 inch flag holds 1.25 cubic feet per linear foot, or 4.63 cubic yards per 100 ft.
What is the flag?
The flag is the flat gutter pan in front of the curb. Its thickness is measured top to bottom.
How do I calculate a plain curb with no gutter?
Set the gutter width to zero. The volume is then length × curb depth × total height.