Concrete Curb Calculator
Find out exactly how much concrete a curb or curb & gutter run needs — bags, cubic yards, joint spacing and cost.
Your curb run
Total height, including buried portion.
Full run length, straight and curved sections combined.
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Per linear ft breakdown
1.38 × 80 lb bags per linear ft
Mixing time
13 h 48 m
One person, 138 bags
Joint planner
The short answer
100 feet of standard 6×18 inch curb needs about 3 cubic yards of concrete, roughly 138 × 80 lb bags once waste is added. Work it out precisely by finding the cross-section area (width × height), multiplying by the run length, adding 5–10% waste, then dividing by your bag’s yield — or converting to cubic yards for a ready-mix order on longer runs.
Concrete needed by curb size
Figures below assume no waste added, per 100 ft of run.
| Curb size | Cross-section | Volume / 100 ft | Cubic yards | 80 lb bags |
|---|---|---|---|---|
| 6×12 in (mountable) | 0.50 sq ft | 50 cu ft | 1.85 | 84 |
| 6×18 in (standard) | 0.75 sq ft | 75 cu ft | 2.78 | 125 |
| 6×24 in (tall barrier) | 1.00 sq ft | 100 cu ft | 3.70 | 167 |
| 8×24 in (wide barrier) | 1.33 sq ft | 133 cu ft | 4.94 | 223 |
| 6×18 in + 24×6 in gutter | 1.75 sq ft | 175 cu ft | 6.48 | 292 |
Past a few cubic yards, most crews order ready-mix rather than mixing hundreds of bags by hand.
Common curb dimensions
| Curb type | Typical width | Typical height | Use |
|---|---|---|---|
| Mountable curb | 6 in | 4–6 in exposed | Low-profile edges, driveways |
| Standard barrier curb | 6 in | 12–18 in total | Streets, parking lots |
| Tall barrier curb | 6–8 in | 18–24 in total | Higher separation, retaining edges |
| Curb & gutter | 6 in + 18–30 in pan | 12–18 in | Combined curb and drainage channel |
Most residential and light commercial curb sits at roughly 6 inches wide by 18 inches tall, with about a third of that buried below the finished grade.
How to calculate concrete for a curb
A curb is a constant cross-section extruded along a length — similar to a strip footing.
- Find the cross-section area. Width × height, both converted from inches to feet.
- Add the gutter pan if applicable. Width × thickness of the pan, added to the curb’s cross-section.
- Multiply by the run length. This gives total cubic feet for the whole curb run.
- Add waste. 5–10% covers spillage and form irregularities.
- Divide by bag yield and round up, or convert to cubic yards (÷27) for a ready-mix order.
Worked example
100 ft of standard curb, 6 in wide, 18 in tall, using 80 lb bags:
- Width in feet6 ÷ 12 = 0.5 ft
- Height in feet18 ÷ 12 = 1.5 ft
- Cross-section area0.5 × 1.5 = 0.75 sq ft
- Volume (× 100 ft)75 cu ft
- Plus 10% waste82.5 cu ft
- Cubic yards82.5 ÷ 27 = 3.06
- Divide by bag yield82.5 ÷ 0.60 = 137.5
- Round up138 × 80 lb bags
At over 11,000 lb of bagged concrete, this is a good candidate for a ready-mix truck rather than hand-mixing.
Curb vs curb & gutter
| Straight curb | Curb & gutter | |
|---|---|---|
| Shape | Simple raised rectangular barrier | Curb plus a sloped gutter pan, poured together |
| Function | Edge definition, traffic separation | Edge definition plus stormwater drainage |
| Typical use | Driveways, medians, light-duty edges | Streets, parking lots with drainage needs |
| Forming | Simple side forms | Forms shaped to the gutter’s slope |
| Concrete volume | Lower per foot | Higher per foot (extra gutter pan) |
Pouring a curb: a quick checklist
- Grade and compact the subgradeA firm, level base keeps the curb’s height consistent along the whole run.
- Set forms to the correct line and gradeCurb relies on accurate forms — small errors compound over a long run.
- Add reinforcement if requiredContinuous rebar or wire mesh helps on traffic-bearing or long unbroken runs.
- Pour and consolidateWork the concrete into the forms to remove air pockets, especially at the gutter flare.
- Tool the finished faceAn edger and finishing trowel give a smooth, durable exposed surface.
- Cut or tool joints on scheduleContraction joints roughly every 10 ft, expansion joints every 40–60 ft.
- Cure and protectKeep fresh curb protected from traffic and heavy rain for the first few days.
Common mistakes
- Skipping joints on long runsWithout planned joints, a curb cracks wherever it wants, usually unevenly.
- Inconsistent form heightSmall dips or rises in the forms show up as a wavy curb line the whole run.
- Underestimating a curb & gutter’s extra volumeThe gutter pan adds real volume — forgetting it under-orders concrete for the whole run.
- Not compacting the subgradeAn unsettled base can cause the curb to shift or crack after traffic loads it.
- Rounding the total instead of per footRound bags per linear foot first when working in sections, so no stretch runs short.
- Opening to traffic too soonVehicle loading before the concrete has cured enough can crack or chip a fresh curb.
What this calculator assumes
Adjust your result if your project differs from these.
- Bag yields of 0.60, 0.45, 0.375 and 0.30 cu ft for 80, 60, 50 and 40 lb bags
- A constant rectangular cross-section extruded along the full run length
- Curb & gutter’s pan treated as a simple rectangular add-on, not a sloped wedge
- Standard concrete mix, not high-strength or fiber-reinforced mixes
- Water of roughly 3 quarts per 80 lb bag
- Mixing at about 6 minutes per 80 lb bag, per person
- Joint spacing guidance (10 ft contraction, 40 ft expansion) is a general rule of thumb, not a stamped design
- Prices are whatever you enter; they are not live market rates
Common questions
How much concrete do I need for a curb?
Multiply the curb’s cross-section area, width times height in feet, by the total run length in feet, add 5 to 10 percent waste, then divide by your bag’s yield. 100 ft of standard 6×18 in curb needs about 3 cubic yards, roughly 138 x 80 lb bags.
What size is a standard concrete curb?
A common residential or municipal curb is about 6 inches wide and 18 inches tall total, with roughly 6 inches buried below grade and 12 inches exposed above the roadway or pavement.
What is the difference between curb and curb and gutter?
A plain curb is just the raised vertical barrier. Curb and gutter combines that curb with a sloped concrete gutter pan poured as one continuous section, channeling water along the edge of the pavement.
How deep should a curb footing go?
Most curbs don’t need a separate footing beyond a compacted gravel base, since the curb itself is typically poured 6 inches or more below the finished grade, similar to a shallow footing.
Do curbs need rebar?
Light-duty residential curbs often skip rebar and rely on properly spaced joints for crack control. Curbs carrying vehicle traffic or built on unstable soil typically use continuous rebar for extra strength.
How far apart should expansion joints be in a curb?
A common rule is contraction joints every 10 feet and expansion joints every 40 to 60 feet, though local specifications vary.
How long does a poured curb need to cure?
Curbs are typically firm enough to remove forms after 24 to 48 hours, but should avoid vehicle or heavy loading for about 7 days, with full strength around 28 days.
Can I pour curb without forms?
Most curb is either hand-formed with wood or metal forms, or placed with a curb machine that extrudes the concrete to shape without traditional forms. Hand-forming is standard for smaller DIY runs.
How much does a linear foot of concrete curb cost?
Material cost per linear foot depends on the curb’s cross-section size and your local concrete price. Multiply the concrete volume per foot by your price per cubic yard or per bag to estimate it.
How many bags of concrete for 100 ft of curb?
For a standard 6×18 in curb, 100 feet needs roughly 3 cubic yards of concrete, about 138 x 80 lb bags including a 10 percent waste allowance.
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Project
| Curb type | — |
| Cross-section | — |
| Total length | — |
| Waste allowance | — |
Per linear ft
| Concrete per ft | — |
| 80 lb bags per ft | — |
Total shopping list
| 80 lb bags | — |
| 60 lb bags | — |
| 40 lb bags | — |
| Water needed | — |
| Dry weight to move | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Assumes a constant rectangular cross-section and standard concrete mix with yields of 0.60, 0.45, 0.375 and 0.30 cu ft for 80, 60, 50 and 40 lb bags. Confirm quantities with your supplier before buying.