Sidewalk Concrete Calculator
Calculate the concrete for a sidewalk or walkway in cubic yards and bags from its length, width and thickness.
How it works
cubic yards = length × width × (thickness ÷ 12) ÷ 27 · bags = volume ÷ bag yield (0.45 cu ft for 60 lb, 0.60 cu ft for 80 lb)
A sidewalk is just a long, narrow slab, so the volume math is the same as any pour: cubic feet from length × width × thickness, then divided by 27 for cubic yards. Four inches is the standard walkway thickness. Bag counts add about 5% for spillage; past roughly half a cubic yard, mixing that many bags by hand stops being worth it.
Worked example
A 40 × 4 ft walkway at 4 in: 40 × 4 × (4 ÷ 12) = 53.3 cu ft, ÷ 27 = 1.98 cubic yards. That is around 124 sixty-pound or 93 eighty-pound bags — well into ready-mix territory.
Frequently asked questions
How wide should a sidewalk be?
Three feet is the minimum for one person; 4 feet lets two people pass and is the common residential width. Public walks are often 5 feet or more to meet accessibility rules.
Do I need control joints?
Yes — tool or saw a control joint about every 4–5 feet, roughly a square pattern, cut to one-quarter of the slab depth. Joints let the inevitable shrinkage cracking happen in straight, hidden lines.
Bags or ready-mix for a sidewalk?
Short walks under half a cubic yard are fine with bags. A long run like this example needs so many bags that a short-load or ready-mix truck is faster, cheaper and more consistent.
Related calculators
Estimates only — add for waste and confirm against local building codes and supplier specs.