Concrete Curb Calculator: Yards, Bags and Cost

Concrete Curb Calculator

Estimate curb and gutter concrete, whole bags, ready-mix, weight, joints and cost.

The gutter slab is counted across its full width; curb height is only the portion above that slab.

Approximates a straight-sided trapezoid. Use the custom-area mode for curved or composite profiles.

Use an area taken from the approved section drawing or calculated separately.

Bags, ready-mix, joints and cost
Reports internal joints per separate run; it does not set the required spacing.
Concrete to order—
—Cross-sectional area
—Total curb length
—Geometric concrete
—Whole bags
—Bag / ready-mix cost
—Planned concrete weight
—Internal joints
—Truck capacity equivalents
—Separate runs

How to calculate concrete for a curb

Choose the cross-section that matches the project drawing, then enter the finished run length. Use curb-and-gutter mode when a raised curb is cast over a continuous gutter slab. The custom-area mode supports approved profiles that are curved or otherwise irregular.

Formulas

Rectangular area = width × height. Curb-and-gutter area = gutter width × gutter thickness + curb width × height above gutter. Trapezoidal area = (top width + bottom width) ÷ 2 × height. Concrete volume = cross-sectional area × length × run count. The allowance applies once to the combined volume.

Checked example

A 100 ft run with a 6 in wide curb rising 6 in above a 24 × 6 in gutter has a 180 in² cross-section and 125 ft³ of geometric concrete. With 10% extra, order 137.5 ft³ = 5.093 yd³, requiring 230 bags at 0.60 ft³ each.

Important limits

  • The calculator estimates concrete quantity; it does not select curb type, profile, joint spacing, reinforcement, subgrade, drainage, slope, strength or accessibility details.
  • The curb-and-gutter formula assumes the curb height entered is above the gutter slab, preventing double-counting.
  • The trapezoid mode uses straight sides. Determine the true cross-sectional area of rolled, parabolic or proprietary profiles and use custom mode.
  • Joint output is a planning count based on the entered maximum spacing, not a design recommendation. Each run is treated separately.
  • Confirm bag yield, density, supplier minimums, short-load fees, pumping, delivery, taxes and access before ordering.

Related calculators

Use the Concrete Calculator for general rectangular pours, the Sidewalk Concrete Calculator for paths and walkways, or the Concrete Driveway Calculator for vehicle slabs.