Concrete Sidewalk Calculator

How it's calculated

The calculator finds the volume in cubic feet: length (ft) × width (ft) × thickness (in ÷ 12). That's converted to cubic yards by dividing by 27. A waste percentage is added on top to cover over-excavation, form loss, and cutting around curves, ramps, or tie-ins, and the adjusted cubic yardage is multiplied by concrete's density to get the weight in tons. Bag counts divide the adjusted cubic feet by each bag's yield; ready-mix truckloads divide the adjusted cubic yards by the truck's capacity.

Worked example

A 4 ft × 50 ft walkway poured 4 inches thick: volume = 4 × 50 × (4 ÷ 12) = 66.67 cubic feet. In cubic yards, that's 66.67 ÷ 27 = 2.47 yd³. Adding a 10% waste factor: 2.47 × 1.10 = 2.72 yd³. At 2.02 tons per cubic yard, that's 2.72 × 2.02 = 5.49 tons — or 5.30–5.51 tons across the 1.95–2.03 density range. In 80 lb bags, the adjusted 73.33 cu ft (66.67 × 1.10) would need 123 bags — technically still under this site's bag-display ceiling, but well past the point where ready-mix usually makes more sense for a run this long.

How deep should it be?

A walkway is a different design problem from a driveway, even though both are concrete slabs: it only has to carry foot traffic, not vehicles, so the thickness math that applies to a driveway doesn't automatically apply here. What actually varies for a walkway is width and layout. How wide it needs to be depends on how it's used — a casual garden path and a primary entry walkway serving a front door don't need the same width, and if the walkway needs to meet accessibility requirements (a code term, not a general suggestion) as a ramp, a public path, or an accessible route to an entrance, width, slope, and surface texture are governed by the ADA and/or your local building code rather than a default this calculator can supply. Control joints matter here too, for the same reason they matter on a patio: concrete shrinks as it cures and will crack somewhere, and a joint layout — usually matched to the walkway's width — decides where that happens instead of leaving it to chance. None of these are numbers this calculator can supply; it converts the length, width, and thickness you already have into a volume and weight. For width, joint spacing, and any accessibility requirement, check your local code, an ADA compliance guide if the path needs to meet that standard, or a contractor familiar with your specific project.

Common mistakes

• –Using a driveway's thickness for a walkway, or vice versa. Foot traffic and vehicle loads are different problems — check what your specific walkway needs to support rather than assuming either default.
• –Not checking accessibility requirements before pouring a primary entry walkway or public path. Width, slope, and surface texture can be governed by the ADA or your local code, and retrofitting a poured slab to meet them is far more expensive than planning for it upfront.
• –Skipping a control joint layout. A narrow walkway still shrinks and cracks as it cures — a joint plan, usually matched to the walkway's width, decides where that crack shows up.
• –Pouring a walkway too narrow for its actual use — a path meant for two people to pass, or for a wheelchair or stroller, needs more width than a casual single-file garden path.
• –Forgetting to account for curves, ramps, or tie-ins to existing paving in the waste factor — a straight rectangular run cuts a lot cleaner than a curved or transitioning walkway.

Where the density figure comes from

Unlike the landscape materials on this site, concrete is a manufactured product with a tightly controlled mix, so its density varies far less than gravel, sand, or mulch — and the same figure applies whether it's poured as a slab, a sidewalk, or any other normal-weight element. CEMEX, a major ready-mix producer, puts a solid unbroken pour at about two tons (4,000 lbs) per cubic yard. ACI 318 and ASTM C138 define normal-weight concrete at 145–150 lb/ft³ — ACI 318 uses 150 lb/ft³ as its default structural value — which works out to 3,915–4,050 lbs (1.96–2.03 tons) per cubic yard. The 1.95–2.03 ton/yd³ range here reflects that normal-weight span, not moisture variation. Lightweight and heavyweight concrete mixes fall outside this range and aren't covered by this calculator. We use 2.02 tons/yd³ as the display figure, drawn from:

• CEMEX — Ready-Mix Concrete Calculator
• ACI 318 & ASTM C138 — normal-weight concrete density, 145–150 lb/ft³

Read more in our density methodology.

FAQ

How much concrete do I need for a walkway?

A 3 ft × 30 ft walkway at 4 inches thick needs about 1.11 cubic yards before waste — use the calculator above to add your waste factor and get a bag count or ready-mix order.

How wide should a walkway be?

It depends on how it's used. A casual garden path can be narrower than a primary entry walkway meant for two people to pass, and a path that needs to serve as an accessible route has its own width requirements under the ADA or your local code. There's no single right width — match it to the walkway's actual purpose.

Does a walkway need to meet accessibility requirements?

It depends on what it serves. A primary entrance walkway or a public path may need to meet ADA or local code requirements for width, slope, and surface texture. Check those requirements before pouring rather than after — retrofitting a poured slab is far more expensive than planning for it upfront.

How is a sidewalk different from a driveway?

A sidewalk only carries foot traffic, while a driveway carries repeated vehicle loads — which is why driveway thickness and subgrade requirements don't automatically apply to a walkway. See the driveway calculator's guidance for that comparison in more detail.

How far apart should control joints be on a walkway?

It depends on the walkway's width and thickness, not a fixed number. Joints let the slab crack in a planned, straight line as it shrinks while curing instead of cracking randomly — plan the layout with whoever pours the slab, or check ACI's guidance on slab-on-grade construction.

Should I use bags or ready-mix for a walkway?

It depends on length. A short walkway or stepping-stone-style path can stay within reach of a bagged DIY pour, but a long run adds up fast — past roughly half a cubic yard, ready-mix delivery is generally cheaper and far less labor than mixing dozens of bags by hand.

Why does concrete's weight vary so little compared to gravel or sand?

Concrete is a manufactured product with a tightly controlled mix ratio, so its density is far more consistent than a quarried or organic material's. The range on this site comes from ACI 318 and ASTM C138's normal-weight concrete specification (145–150 lb/ft³), the same figures used across every concrete calculator here, not from moisture swings the way gravel, sand, or mulch vary.