Concrete Curb Calculator

A concrete curb calculator that works from the profile cross section instead of length times width times depth, and handles curved radius runs, forms and joints.

By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.

Quick answer: Curb volume is the cross section of the chosen profile times the linear feet, not length times width times depth. A 6 by 18 in barrier curb has a 0.75 sq ft section, so 150 ft of it takes 4.5 cubic yards with 8 percent waste.

Your measurements

A length built from stock pieces: total length divided by piece length, rounded up, with the last piece cut.

Curb profileThe profile sets the cross section, which is what the volume comes from. A curb and gutter combination holds close to twice the concrete of a barrier curb of the same height.Straight runftMeasured along the face of the curb, which is the line the plans dimension and the line the pay item is measured on.Curved runftArc length along the face of the curb, not the straight line between the tangent points. Leave it at zero for a run with no curve.Curve radiusftRadius to the face of the curb. VDOT standard CG-2 pays anything at 300 ft or less as radial curb, because curved forms cost more per foot.Curb face heightinExposed face from the gutter line to the top of the curb. Oregon DOT RD700 allows 6 to 9 in and uses 7 in as its standard exposure.Control joint spacingftOhio street details tool contraction joints every 10 ft. Oregon DOT RD700 caps them at 15 ft, so 10 to 15 ft covers most street standards.Waste allowance%Curb spills at the form ends and a slipform machine wastes the first few feet while the mix settles. 5 to 10% is normal.Price per cubic yard (optional)$/cu ydReady mix is typically $150 to $220 per cubic yard delivered in 2026, before delivery and short load fees.

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Concrete needed4.5 cu ydAll results

Results

Concrete needed: 4.5 cu yd; 121.5 cu ft of concrete from 150 ft of barrier curb, including 8% waste. Plants batch in quarter yard steps, so this is rounded up to one
Cross section: 0.75 sq ft; 6 in wide by 18 in deep, with 6 in standing above the gutter line. One cubic yard places 36 ft of this profile
Forms to set: 300 ft; Face and back of the whole run. 60 ft of that bends to the curve, so it takes bender board or flexible steel form, and the back form runs a longer radius than the face
Curve layout: 68.8°; Chord 28.2 ft, middle ordinate 4.4 ft out to the face of the curb at the center of the arc. A face radius of 300 ft or less is billed as radial curb under VDOT standard CG-2
Control joints: 14 joints; 15 panels at 10 ft centers, tooled or sawed at least 2 in deep.
Expansion joints: 2 joints; 0.5 in preformed fiber filler cut to the shape of the section, 1.5 sq ft in all. RD700 puts them at 200 ft maximum spacing, at both points of tangency, and at the end of every driveway
Dowels at tie ins: 4 No. 4 bars; 18 in long, epoxy set 9 in into the existing curb, two bars at each end of the run. The curb itself is unreinforced and the joints do the crack control

Concrete Curb formula

Cross section (sq ft) = Profile area in square inches / 144
Cubic feet = Cross section x (Straight run + Curved run)
Cubic yards = Cubic feet x (1 + Waste %) / 27
Form length = 2 x Total run, of which 2 x Curved run has to bend
Curve sweep (degrees) = Curved run / Radius x 180 / 3.1416

Worked example

A 240 ft street frontage in curb and gutter. The run is 200 ft straight plus 40 ft around a 15 ft radius at the driveway apron, with a 7 in face and joints at 12 ft.

The section is a 24 in gutter flag 7 in thick plus a 6 in wide curb 7 in tall. That is 168 + 42 = 210 square inches, or 1.46 sq ft. Times 240 ft that is 350 cubic feet, and 8 percent waste brings it to 378 cubic feet, or 14 cubic yards even. Forms come to 480 ft with 80 ft of it bending. The 40 ft arc on a 15 ft radius sweeps 152.8 degrees, a 29.2 ft chord with an 11.5 ft middle ordinate. Joints at 12 ft give 20 panels and 19 control joints, plus 3 expansion joints: one from the 200 ft rule and one at each point of tangency.

Quick reference

Concrete per linear foot by curb profile, at a 6 in face height
Profile	Section modeled	Cu ft per lin ft	Cu yd per 100 ft	Lin ft per cu yd
Barrier curb	6 in wide x 18 in deep	0.75	2.78	36
Mountable or rolled curb	12 in wide base 6 in deep, face tapering 12 in to 4 in	0.83	3.09	32
Curb and gutter, 24 in	7 in gutter flag, 6 in curb	1.42	5.25	19
Curb and gutter, 30 in	7 in gutter flag, 6 in curb	1.71	6.33	16
Ohio combined curb and gutter	24 in wide, 8 in gutter, 6 in curb, as drawn on STR-05	1.59	5.89	17
Landscape edging curb	6 in wide x 6 in deep	0.25	0.93	108

Why curb is a cross section, not a slab

A slab is length times width times depth because every point in it is the same depth. A curb is not. A barrier curb is a tall narrow block. A rolled curb tapers from a 4 in top out to a 12 in base over a 6 in deep foot. A curb and gutter is a flat 24 in gutter flag with a curb standing on the back of it. The only thing they share is that the shape repeats every foot, so the volume is the area of one cross section times the linear feet.

That is why the numbers spread so far apart. At a 6 in face height a barrier curb is 0.75 cubic feet per foot and a 24 in curb and gutter is 1.42. The same 150 ft of frontage is 4.5 cubic yards one way and 8.5 the other, both ordered with 8 percent waste. Landscape edging at 6 by 6 in is 0.25 cubic feet per foot, which is why a garden curb prices out at a third of a street curb. Check your local standard drawing before you order, because a 30 in gutter flag is common in the West and adds another 20 percent.

Radius work, joints and the curb machine

Curved curb costs more per foot than straight curb and the standards say so out loud. VDOT CG-2 note 3 pays anything with a face radius of 300 ft or less as radial curb. On a tight radius the face form and the back form run two different radii, and both need bender board or flexible steel. Crews set stakes at a third of the usual spacing to keep the arc fair. Measure the curved part as arc length along the face, not as the straight line between the tangent points.

Joints are where curb usually fails. Oregon DOT RD700 tools contraction joints at 15 ft maximum and many Ohio street details use 10 ft, cut at least 2 in deep. Expansion joints go in at 200 ft maximum, at both points of tangency on a curve, and at the end of every driveway. Use 1/2 in preformed fiber filler cut to the shape of the section. On runs over about 200 ft a slipform machine beats hand forming on both cost and finish. It wants graded, compacted subgrade and several feet of clear room beside the string line.

What this calculator leaves out

The result is concrete for the curb section only. It leaves out trench excavation and spoil haul off. It leaves out the compacted aggregate base that most street standards put under the curb. It leaves out the underdrain Ohio and several other states run behind a combined curb and gutter. The pavement that butts the gutter line is priced separately, and so is sawing out the existing curb. Also outside it: curb ramps and detectable warning panels, inlet castings, backfill and topsoil behind the curb, and curing compound. Work in a public right of way needs a permit, usually a bond and an inspection. Your city standard drawing, not this page, sets the section you are allowed to pour.

Code limits that apply

ODOT RD700 note 1checked
Curb exposure 6 to 9 in above the gutter line, 7 in standard
If you miss it: A curb under 6 in gets jumped and parked over, and one over 9 in scrapes bumpers and fails the ramp transition
ODOT RD700 note 3checked
Contraction joints at 15 ft maximum spacing, and at the ends of each inlet and curb ramp
If you miss it: Curb poured in long unjointed runs cracks on its own line, usually diagonally through the face
ODOT RD700 note 2
Expansion joints at 200 ft maximum, at points of tangency, and at the end of every driveway
If you miss it: With no relief joint at a curve or a driveway the curb spalls at the corner as the run expands
VDOT CG-2 note 3checked
Curb with a face radius of 300 ft or less is paid as radial curb
If you miss it: Radial curb billed at the straight rate leaves the forming labor and bender board unpaid on the change order
VDOT CG-2 note 4
Standard 6 in curb is 18 in deep, reducible to 15 in or increased to 21 in
If you miss it: A curb poured shallow to stretch the yardage rocks loose the first time a truck tire climbs it
VDOT CG-6
Combination 6 in curb and gutter is 2 ft wide with a 7 in minimum gutter depth
If you miss it: A thin gutter flag cracks under the wheel loads that track the gutter line at every driveway

Provision	Limit	If you miss it
ODOT RD700 note 1checked	Curb exposure 6 to 9 in above the gutter line, 7 in standard	A curb under 6 in gets jumped and parked over, and one over 9 in scrapes bumpers and fails the ramp transition
ODOT RD700 note 3checked	Contraction joints at 15 ft maximum spacing, and at the ends of each inlet and curb ramp	Curb poured in long unjointed runs cracks on its own line, usually diagonally through the face
ODOT RD700 note 2	Expansion joints at 200 ft maximum, at points of tangency, and at the end of every driveway	With no relief joint at a curve or a driveway the curb spalls at the corner as the run expands
VDOT CG-2 note 3checked	Curb with a face radius of 300 ft or less is paid as radial curb	Radial curb billed at the straight rate leaves the forming labor and bender board unpaid on the change order
VDOT CG-2 note 4	Standard 6 in curb is 18 in deep, reducible to 15 in or increased to 21 in	A curb poured shallow to stretch the yardage rocks loose the first time a truck tire climbs it
VDOT CG-6	Combination 6 in curb and gutter is 2 ft wide with a 7 in minimum gutter depth	A thin gutter flag cracks under the wheel loads that track the gutter line at every driveway

Rows marked checked produce a warning in the results when an entry crosses the limit. The others are on the plans or on site and this calculator does not test them. Local amendments can be stricter; the adopted edition and the inspector govern.

Mistakes that cost money

Figuring curb as length times width times depth. A 24 in curb and gutter holds nearly twice what a barrier curb does.
Ordering off the straight run only. Radial curb is a separate pay item under VDOT CG-2 at any face radius of 300 ft or less.
Skipping the expansion joint where a curve starts and ends. RD700 calls for one at each point of tangency, not just every 200 ft.
Tooling contraction joints under 2 in deep. They stop steering the crack and the curb breaks between them instead.
Buying straight 2x4 form stock for a curve. The back form runs a longer radius than the face, so both need bender board.
Booking a slipform machine on a tight site. It needs several feet of clear, graded room beside the line and cannot run against a fence.

Key facts

A barrier curb 6 in wide and 18 in deep holds 0.75 cubic feet of concrete per linear foot, so one cubic yard places 36 ft of it.
A 24 in curb and gutter with a 7 in gutter flag holds 1.42 cubic feet of concrete per linear foot, or 19 ft to the cubic yard.
Oregon DOT standard drawing RD700 sets curb exposure at 6 to 9 in above the gutter line, with 7 in as the ODOT standard.
Oregon DOT standard drawing RD700 spaces curb contraction joints no more than 15 ft apart and expansion joints no more than 200 ft apart.
VDOT standard CG-2 pays any curb with a face radius of 300 ft or less as radial curb, a separate pay item from straight curb.
The City of Marysville, Ohio combined curb and gutter drawing STR-05 publishes its section as 1.59 cubic feet of concrete per linear foot.

Frequently asked questions

How much concrete is in a linear foot of curb?

A 6 by 18 in barrier curb takes 0.75 cubic feet per foot, so one cubic yard places 36 ft. A 24 in curb and gutter with a 7 in gutter takes 1.42 cubic feet per foot, or 19 ft to the yard.

How do you calculate curb and gutter concrete?

Break the section into rectangles, add them up, and multiply by the run. A 24 in gutter flag 7 in thick is 168 square inches. A 6 in wide curb 6 in tall adds 36, and 204 square inches is a 1.42 sq ft section, or 1.42 cubic feet of concrete per foot.

How do I figure a curb on a radius?

Measure the curved part as arc length along the face of the curb and enter it separately. The concrete per foot does not change, but the forming does, and VDOT bills any face radius of 300 ft or less as radial curb.

How far apart do joints go in concrete curb?

Contraction joints run 10 to 15 ft apart, cut at least 2 in deep. Expansion joints go at 200 ft maximum, at both ends of every curve, and at the end of each driveway.

Sources and references

Standard Drawing RD700, Curbs: standard, mountable, curb and gutter sections and joint spacing (Oregon DOT)
Standard CG-2, Standard 6 in Curb, 2016 Road and Bridge Standards sheet 201.01 (Virginia DOT)
Standard CG-6, Combination 6 in Curb and Gutter, 2016 Road and Bridge Standards sheet 201.03 (Virginia DOT)
Standard Construction Drawing STR-05, Combined Curb and Gutter, concrete quantity per linear foot (City of Marysville, Ohio)

Next steps for this project

The usual order for a concrete & masonry project. See all concrete & masonry calculators.

Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.