Concrete Curb Calculator
Building concrete curbs? Calculate exactly how much concrete you need with our free tool. Get instant curb estimates.
Pro Tips
- →Standard curb height is 6-8 inches
- →Curb width typically matches height (6x6 inches)
- →Include rebar for curbs longer than 20 feet
- →Add expansion joints every 10-20 feet
- →Compact gravel base thoroughly
Includes 10% waste factor
That's typically a professional pour. See costs ↓
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Cost Estimate
Estimated material costs for your project
Recommendation: Bagged Concrete
For smaller projects, bagged concrete gives you more control and less waste.
23 bags × 80lb
0.51 cubic yards + delivery
Prices vary by location and time. Contact local suppliers for accurate quotes.
For general step-by-step instructions, read our complete When To Use Rebar and How To Pour Concrete.
Concrete Curb Types and How They Affect Volume
The word "curb" covers several distinct profiles, and each one uses a different amount of concrete per linear foot. Picking the right type first is what makes your volume estimate accurate.
| Curb Type | Typical Cross-Section | Where It's Used |
|---|---|---|
| Barrier curb | 6 in wide × 18 in deep (6-in reveal) | Streets, parking lots — vertical face stops vehicles |
| Mountable / roll curb | 6 in reveal, rounded face, ~12 in wide | Residential driveways, subdivisions — cars can roll over it |
| Curb-and-gutter | 6-in curb + 18–24 in gutter pan | Roadways needing drainage along the curb line |
| Garden / landscape edging | 4–6 in wide × 4–6 in deep | Beds, walkways — decorative containment only |
There are also two ways to place any of these: extruded (slipform) and formed (hand-built wood or steel forms). Extruded curb is machine-laid with stiff, low-slump concrete and needs no side forms, which is fast for long runs. Formed curb is built by hand against forms and is the practical choice for short residential jobs, tight radii, and tie-ins. The profile and dimensions drive volume; the placement method drives labor, not concrete quantity.
How Cross-Section Sets Volume Per Linear Foot
A curb is just a long prism, so its volume is cross-sectional area × length. Nail down the cross-section in square feet and every other number falls out. For a rectangular barrier curb, area equals width × height; for curb-and-gutter you add the gutter pan (its width × thickness) to the curb area.
Convert inches to feet (divide by 12), multiply width × height to get square feet of cross-section, then multiply by length and divide by 27 to reach cubic yards. A 6 in × 18 in barrier curb has a cross-section of 0.5 ft × 1.5 ft = 0.75 sq ft, so every linear foot uses 0.75 cu ft — that's 0.0278 cubic yards per foot before waste.
Cubic Yards and Bags Per Linear Foot by Cross-Section
The table below gives concrete per single linear foot for common profiles, plus 80-lb bag equivalents (one 80-lb bag yields about 0.022 cu ft … 0.6 cu ft, so roughly 45 bags per cubic yard). Multiply the per-foot figure by your total length, then add 10% waste.
| Cross-Section (W × H) | Sq Ft | Cu Ft / ft | Cu Yd / ft | 80-lb Bags / ft |
|---|---|---|---|---|
| 6 × 6 in (residential) | 0.25 | 0.25 | 0.0093 | 0.42 |
| 6 × 8 in (commercial) | 0.33 | 0.33 | 0.0123 | 0.55 |
| 6 × 18 in barrier | 0.75 | 0.75 | 0.0278 | 1.25 |
| 8 × 8 in (heavy) | 0.44 | 0.44 | 0.0165 | 0.74 |
| Curb-and-gutter (6×18 + 24×6 pan) | 1.75 | 1.75 | 0.0648 | 2.92 |
These figures assume full-depth concrete with no void. For curb-and-gutter, the gutter pan more than doubles the concrete versus a plain barrier curb of the same height, which is the single biggest surprise in most curb estimates.
Total Volume by Curb Length
Once you know cubic yards per foot, scaling to your run is simple multiplication. The table shows total concrete (including 10% waste) for the two most common residential profiles across typical project lengths.
| Length | 6 × 6 in Curb (cu yd, +10%) | 6 × 18 in Barrier (cu yd, +10%) |
|---|---|---|
| 20 ft | 0.20 | 0.61 |
| 50 ft | 0.51 | 1.53 |
| 100 ft | 1.02 | 3.06 |
| 200 ft | 2.04 | 6.12 |
| 500 ft | 5.10 | 15.30 |
At the 100-ft residential mark, a 6 × 6 curb sits right at 1 cubic yard — the practical break point where bagged mix and a small ready-mix load both make sense. Above about 2 cubic yards, ordering ready-mix is almost always cheaper and faster than mixing bags by hand. For a full materials-and-labor estimate, run your numbers through the concrete cost calculator.
Concrete Strength: Slipform vs. Hand-Formed
Curb concrete is specified by compressive strength and by slump, and the right mix depends on the placement method.
| Application | Target Strength | Slump | Notes |
|---|---|---|---|
| Residential / landscape curb | 3,000 PSI | 3–4 in | Hand-formed, workable mix |
| Street and parking-lot curb | 3,500–4,000 PSI | 3–4 in | Higher abrasion and impact resistance |
| Slipform / extruded curb | 4,000 PSI | 1–3 in | Stiff, low-slump so it holds shape with no forms |
Slipform curb runs a deliberately stiff, low-slump mix — the concrete has to stand on its own the instant the machine passes. Hand-formed curb can use a wetter, more workable 3–4 inch slump because the forms hold the shape until it sets. For freeze-thaw climates, specify 4,000 PSI with 5–7% air entrainment to resist scaling.
Joints, Rebar, and Drainage Slope
Three details separate a curb that lasts from one that cracks and heaves in the first winter.
- Expansion joints belong every 10–20 feet and at every structure tie-in (catch basins, driveways, existing curb). Use a premolded filler the full depth of the section. Contraction (control) joints — shallow tooled or saw-cut grooves about one-quarter of the curb depth — go every 5–10 feet between expansion joints to steer cracking to a hidden line. See the concrete joint problems guide for spacing and depth detail.
- Rebar is recommended for any curb run over 20 feet. Run one or two #3 or #4 bars lengthwise through the center; lap splices 12–18 inches and keep bars 2–3 inches off the subgrade. Curbs that take vehicle contact benefit from continuous longitudinal steel. Our rebar guide and rebar vs. mesh vs. fiber comparison cover sizing.
- Drainage slope is the whole point of curb-and-gutter: the gutter pan should fall 1–2% (about 1/8 to 1/4 inch per foot) toward catch basins so water never ponds against the curb face. Curb on its own simply contains and channels runoff — see the driveway drainage guide for tie-in detail.
Get the cross-section, joints, and slope right and the volume math takes care of itself. Enter your curb length and dimensions in the calculator above for an exact cubic-yard and bag count, then use the concrete cost calculator to price the full job.