Key numbers
- 4 ft wide, 4 in thick: 0.49 yd³ per 10 ft of walk
- 1 yd³ pours 20¼ ft of a 4 ft walk at 4 in, 27 ft of a 3 ft walk
- 4 × 50 ft walk: 2.47 yd³, order 2¾ yd³ or 123 × 80 lb bags
- Joints: 1 in deep every 6–8 ft (QUIKRETE data sheet)
On this page
How to use the Concrete Sidewalk Calculator
- 1Pick your unitsEvery dimension has its own unit menu (in, ft, yd, cm or m); changing one converts that number so the size stays the same. The US / Metric switch sets all fields to feet and inches or meters and centimeters and resets them to typical values.
- 2Enter the dimensionsType the length (default feet), width (default feet) or thickness (default inches). Measure the inside of the forms and the depth in several places.
- 3Set waste and quantityUse the waste slider (0 to 20%, default 10%) and allow more on uneven ground. If you have several identical pours, enter how many.
- 4Read the resultsSee the volume in cubic yards, cubic feet and cubic meters, the ready-mix order rounded up to ¼ yard, the number of 90, 80, 60, 50 and 40 lb bags rounded up, and the weight at the density you choose (150, 145 or 140 lb/ft³).
- 5Price it and save itPick a pricing basis (per cubic yard, per cubic meter or per bag of the highlighted size) and enter your local price for a material cost. Use Add to project to total several pours, and Copy link to share the exact result.
Results update as you type. Back to the calculator ↑
How to calculate concrete for a sidewalk
A sidewalk is a long, narrow slab, so its volume is length × width × thickness. Measure length and width in feet and thickness in inches, then:
Cubic yards = length (ft) × width (ft) × thickness (in) ÷ 324
The 324 converts inches and cubic feet to cubic yards in one step (12 × 27). For cubic feet, divide by 12 instead.
- Measure the full run along the centre line, including the bends. Add short branches to the door or driveway as separate pieces.
- Measure the width inside the forms.
- Set the thickness, commonly about 4 in for a home walk; more where vehicles cross.
- Add 10% and round up to the next ¼ yd³ or whole bag.
Worked example: 4 × 50 ft front walk, 4 in thick
- 50 × 4 × 4 ÷ 324 = 2.47 yd³ (66.7 ft³)
- Add 10%: 2.72 yd³ → order 2¾ yd³
- In bags: 73.3 ft³ ÷ 0.60 ft³ = 123 × 80 lb bags
- Weight in place: about 10,000 lb (150 lb/ft³)
Concrete per length of sidewalk
Sidewalks are planned by the foot, so this table gives yards for common widths and lengths at 4 in thick. Each cell shows the exact volume, the ready-mix order with 10% extra, and 80 lb bags with 10% extra.
| Width | 10 ft | 25 ft | 50 ft | 100 ft |
|---|---|---|---|---|
| 3 ft | 0.37 yd³ (½; 19 bags) | 0.93 yd³ (1¼; 46 bags) | 1.85 yd³ (2¼; 92 bags) | 3.70 yd³ (4¼; 184 bags) |
| 4 ft | 0.49 yd³ (¾; 25 bags) | 1.23 yd³ (1½; 62 bags) | 2.47 yd³ (2¾; 123 bags) | 4.94 yd³ (5½; 245 bags) |
| 5 ft | 0.62 yd³ (¾; 31 bags) | 1.54 yd³ (1¾; 77 bags) | 3.09 yd³ (3½; 153 bags) | 6.17 yd³ (7; 306 bags) |
A quick rule: at 4 in thick, one cubic yard pours 81 ÷ width (ft) feet of walk, which is 27 ft of a 3 ft walk, 20¼ ft of a 4 ft walk and 16.2 ft of a 5 ft walk. At 5 in, a 4 ft walk uses 0.62 yd³ per 10 ft; at 6 in, 0.74 yd³.
How wide and how thick should a sidewalk be?
Most home walkways are 3–4 ft wide and about 4 in thick. Those are common practice. Public sidewalks follow the city’s standard drawing, and accessible routes have federal minimums.
- Width. The 2010 ADA Standards require at least 36 in (915 mm) of clear width on an accessible route (section 403.5.1). Two people pass comfortably on 4–5 ft.
- Thickness. About 4 in is common for foot traffic. Where a car crosses the walk, such as at the driveway, the slab is usually thickened to match the driveway: check local code.
- Slope. Cross slope on an accessible route is limited to 1:48 (403.3), about ¼ in per foot, enough to shed water.
If the walk is in the public right-of-way, ask the city or county for its sidewalk detail before you form it. It sets the width, thickness, joints and any permit.
Replacing sidewalk panels
Repairs are usually done panel by panel between joints. Measure one panel, multiply by the number of panels and keep the 10% allowance.
| Repair | Volume | 80 lb bags (+10%) |
|---|---|---|
| One 4 × 4 ft panel, 4 in | 5.3 ft³ (0.20 yd³) | 10 |
| One 4 × 5 ft panel, 4 in | 6.7 ft³ (0.25 yd³) | 13 |
| Two 4 × 4 ft panels, 4 in | 10.7 ft³ (0.40 yd³) | 20 |
| 4 × 30 ft run, 4 in | 40 ft³ (1.48 yd³) | 74 |
Old concrete weighs about 50 lb per square foot at 4 in, so a 4 × 5 ft panel is roughly 1,000 lb of debris. Plan disposal before you break it out; the concrete removal cost page covers hauling.
Base, forms and joints
- Base. A compacted gravel base is common under walks. 4 in of base under a 4 × 50 ft walk is 2.47 yd³, about 3.5 tons; size it with the gravel calculator.
- Forms. 2×4 lumber set on edge forms a 3½ in walk, not 4 in. Use 2×6 boards or set the 2×4s on a deeper base cut if you want a full 4 in.
- Control joints. QUIKRETE’s data sheet calls for joints 1 in deep every 6–8 ft. On a 4 ft walk, many builders cut a joint every 4–5 ft so the panels stay close to square.
- Expansion joints. Where the walk meets the house, steps or a driveway, a pre-moulded joint strip keeps the slabs separate.
Bags or ready-mix for a sidewalk?
A short path under about ½ yd³ (around 23 × 80 lb bags, about a 4 × 10 ft walk at 4 in) is practical with bags. Longer walks are easier with ready-mix, especially if the truck can reach the forms. A 4 × 50 ft walk is 123 bags, about 9,800 lb to lift and mix. Ask the plant about its minimum load and short-load fee, and take the order to the concrete sidewalk cost page to price it.
Common sidewalk estimating mistakes
- Measuring straight across a curve. Follow the centre line of the walk.
- Nominal lumber. A 2×4 form is 3½ in tall; a “4 in” walk formed with it holds 12.5% less concrete than planned, and the walk is thinner too.
- Forgetting the landing or apron. The wider pad at the door or the driveway crossing is extra concrete.
- No allowance. Running out on a long walk leaves a cold joint mid-panel. Keep the 10%.
For wide pads and patios use the concrete patio calculator; for any other flat slab, the concrete slab calculator.
FAQ
Frequently asked questions
How much concrete do I need for a 4×50 sidewalk?
A 4 × 50 ft sidewalk 4 in thick needs 2.47 cubic yards (66.7 ft³). With 10% extra, order 2¾ yd³ of ready-mix or buy 123 bags of 80 lb concrete. At 5 in it needs 3.09 yd³.
How many bags of concrete for a 4×25 sidewalk?
62 bags of 80 lb concrete, or 82 bags of 60 lb, for a 4 × 25 ft walk 4 in thick, including 10% extra. The exact volume is 1.23 yd³ (33.3 ft³), so a 1½ yd³ ready-mix order is an easier option.
How many feet of sidewalk does a yard of concrete pour?
At 4 in thick, 1 cubic yard pours 20¼ ft of a 4 ft wide sidewalk, 27 ft of a 3 ft walk and 16.2 ft of a 5 ft walk. Divide 81 by the width in feet to get the length.
How many bags of concrete for a 3×20 walkway?
37 bags of 80 lb concrete, or 49 bags of 60 lb, for a 3 × 20 ft walkway 4 in thick with 10% extra. The exact volume is 0.74 yd³ (20 ft³).
How thick should a concrete sidewalk be?
Residential sidewalks are commonly poured about 4 in thick, thicker where vehicles cross, such as at a driveway. That is common practice, not code; city sidewalks follow the local public-works standard. Going from 4 to 5 in adds 0.12 yd³ per 10 ft of 4 ft walk.
How wide should a sidewalk be?
3–4 ft is common for a home walkway, and 4 ft or more where two people walk side by side. An accessible route needs at least 36 in (915 mm) of clear width under the 2010 ADA Standards (403.5.1). A 4 ft walk uses a third more concrete than a 3 ft walk.
How much concrete to replace one sidewalk panel?
One 4 × 5 ft panel at 4 in needs 6.7 ft³, or 13 bags of 80 lb concrete with 10% extra. Two 4 × 4 ft panels need 0.40 yd³, about 20 bags.
How much does a concrete sidewalk weigh?
About 50 lb per square foot at 4 in thick, using 150 lb/ft³ for normal concrete. A 4 × 100 ft walk weighs about 20,000 lb. Use this when planning removal and hauling.
3 Sources
- QUIKRETE Concrete Mix (No. 1101) data sheet: 80 lb bag yield 0.60 ft³; listed uses include sidewalks; control joints 1 in deep every 6–8 ft
- U.S. Access Board, 2010 ADA Standards for Accessible Design: 403.5.1 clear width of walking surfaces
- WSDOT Bridge Design Memo 05-2010: normal-weight concrete 150 lb/ft³
Last reviewed October 12, 2026 by M Bilal. Found an error? Tell us.