Concrete Curb Calculator
This concrete curb calculator (kerb calculator outside North America) computes curb-and-gutter volumes from the standard cross-section: curb face plus gutter flag, multiplied along the run.
How to Use This Calculator
- Enter your dimensions — feet for lengths, inches for thickness.
- Adjust the options — waste percentage, bag size and your local concrete price.
- Read your results — volume, bags, weight and cost update live as you type.
The Formula
Volume = [curb depth × (curb height + flag thickness) + gutter width × flag thickness] × length Worked example: A 6×6 in curb with 12 in gutter at 6 in thick over 50 ft: [0.5×1 + 1×0.5] × 50 = 50 ft³ ≈ 1.85 yd³.
Curb and gutter is priced and poured by the linear foot, but ordered by the cubic yard — this calculator bridges the two. The standard 6-inch curb with 12-inch gutter runs almost exactly 1 ft³ per linear foot.
Using this as a concrete kerb calculator? Same geometry: a British 125 × 255 mm kerb bedded on concrete uses the curb-only mode (set gutter width to 0) plus your haunching allowance.
Curb work is formed tight and screeds clean, so 5% waste usually suffices on machine pours; hand-formed radius work merits 10%.
Frequently Asked Questions
Common questions about the concrete curb calculator.
How much concrete per foot of curb and gutter?
The standard 6 in curb + 12 in gutter section uses ≈ 1 ft³ per linear foot — so 27 linear feet per cubic yard.
What's the difference between curb and kerb?
Spelling only — curb (US) and kerb (UK/AU/NZ). The volume math is identical; enter your section dimensions in inches or centimeters.
Can I calculate curb without a gutter?
Yes — set gutter width to 0 and the tool computes the curb prism alone: depth × height × length.
What mix is used for curbs?
Typically 3,500–4,000 psi (M25–M30) with air entrainment in freeze-thaw climates; slip-formed curb uses a very low-slump version of the same mix.
Related Calculators
More tools from the concrete calculator family.