Calculate concrete for a straight sidewalk or a route made from multiple measured segments. Each segment contributes its own area and thickness, which is useful at turns and branches where a single bounding rectangle would include space that is not part of the walk.
Measure each sidewalk run
For each standard flat segment, enter length, width, and thickness. Add another segment where the path turns, changes width, or branches. At a corner, split the path so the shared rectangle belongs to one segment only; overlapping two full rectangular measurements would count the same concrete twice. If you know a segment’s surface area but the path is irregular, use the area input together with its specified thickness.
Keep each run’s measurements visible in the summary. A sidewalk can taper or have separate landings, curb ramps, or widened areas that do not match a constant rectangle. Add those as their own measured regions only when their footprints do not overlap the main run. If thickness changes by location, enter each thickness zone separately. Do not use the patio circle option to approximate a curved path unless the actual concrete footprint is circular.
Flat-segment volume and slope measurements
For a flat rectangular segment, multiply length by width by thickness after converting to a common unit. Add the cubic-foot volumes and divide by 27 for cubic yards. The order quantity applies the adjustable allowance once to the combined net amount: V_order = Σ(L × W × T) × (1 + allowance ÷ 100). The default 10% is a planning setting, not a required value. Keep the unit label next to thickness because inches and feet differ by a factor of twelve.
For the optional slope path, use the actual length measured along the walking surface, its width, and thickness measured perpendicular to that sloped surface. A different model can use horizontal plan projection area with a vertical thickness. Do not combine slope length with vertical thickness in the same formula unless the geometry matches; that mixes directions and produces an incorrect volume. The slope diagram should show exactly which surface length and thickness the selected mode expects.
Worked example: two flat sidewalk runs
Consider a 50 ft × 4 ft segment and a separate 20 ft × 3 ft segment, both 4 in thick. Their areas are 200 ft² and 60 ft², for 260 ft² total. At 4 in, or one-third of a foot, net volume is 260 × ⅓ = 86.667 ft³, about 3.20988 yd³. Applying a 10% allowance once gives about 95.333 ft³, or 3.53086 yd³ to plan for.
With QUIKRETE Concrete Mix No. 1101 at approximate yield of 0.60 ft³ per 80 lb bag, that adjusted volume requires 159 bags after rounding up. The example assumes both runs share one consistent thickness and do not overlap. If the two segments meet at a corner, decide where the shared area belongs before entering them. The total square footage is useful for checking the measured route, but cubic yards are the order quantity because depth is included.
A separate example for a sloped walk
Suppose a sloped section has a 5 ft measured surface length, a 3 ft width, and 0.5 ft thickness perpendicular to that surface. Its idealized volume is 5 × 3 × 0.5 = 7.5 ft³. The actual surface length is longer than its horizontal projection, so using the projected distance with a normal thickness would understate the modeled surface volume. The example is about measurement directions, not a recommended slope or slab thickness.
If your plan instead specifies a horizontal area and thickness measured vertically, use those matching quantities in the ordinary prism calculation. A surface with cross-slope, variable thickness, or an irregular transition may need to be separated into zones. Confirm how the plan defines dimensions before entering values. Do not assume every sidewalk is level, or that one average dimension captures a cross-slope, curb return, ramp, or drainage channel.
From combined volume to an order
The calculator can show segment subtotals and the combined net quantity before allowance. That makes it easier to catch an omitted branch or duplicate corner. Small segment volumes should be added before rounding; do not round every run to a whole cubic yard and then sum. If the sections will be poured at different times, keep separate order plans where needed and check whether each pour has its own material allowance or supplier minimum.
A bag equivalent uses a selected product yield. A ready-mix supplier may use minimum orders, partial-load charges, or delivery increments that are not determined by this geometry. Ask about site access, truck routing, timing, and any pump or placement equipment. The sidewalk cost page is not a dedicated pricing page in the defined set; use a relevant quote or general cost tool when cost is needed, and do not apply a driveway or patio price as if it were a sidewalk-specific rate.
Design and measurement boundaries
This page estimates quantity for measured surfaces. It does not design sidewalk thickness, reinforcement, control joints, base, drainage, slope, ramp geometry, or accessibility. Follow project documents and local requirements for those decisions. The result does not indicate that the path will drain correctly or meet a particular accessibility criterion. A valid volume is only as reliable as the dimensions and geometry entered.
Before ordering, verify width at each change, actual path length, thickness units, non-overlap, selected allowance, and whether the result is net or order volume. For a neighborhood path, record each segment in order so the site layout can be compared with the calculation. If the walk runs alongside a curb, calculate the sidewalk and curb sections separately and review whether their concrete footprints share any volume at their joint. Use the concrete quantity guide for a general measure-to-order workflow.
Frequently asked questions
Can I add several sidewalk sections?
Yes. Add each measured run, then check that adjacent rectangles do not overlap at turns, branches, or landings.
How is a sloped sidewalk measured?
The slope mode uses the actual surface length, width, and thickness perpendicular to that surface. A horizontal-projection mode requires matching vertical thickness instead.
How much concrete for the two-run example?
The 50 × 4 ft and 20 × 3 ft runs at 4 in thickness total 3.20988 yd³ net and about 3.53086 yd³ with 10% allowance.
Does the calculator choose sidewalk thickness?
No. It estimates a volume from a thickness you enter and does not determine design or accessibility requirements.
Can I enter a curved sidewalk?
Use measured area or split the route into simple regions without overlap. Avoid using a single rectangle that includes unpaved space.
How many 80 lb bags does the example use?
At the approximate 0.60 ft³ yield for QUIKRETE Concrete Mix No. 1101, the adjusted example quantity rounds up to 159 bags.