How much concrete is a 3×20 sidewalk?
A 3-by-20-foot sidewalk covers 60 square feet. At the standard 4-inch thickness that's about 0.74 cubic yards of concrete before waste, or roughly 0.81 yards once you add a 10% allowance. At about 0.81 cubic yards this pour is below the one-yard minimum most ready-mix plants set, so expect a short-load surcharge or consider bagged mix for a job this small. The calculator above is pre-filled to these dimensions; change the thickness or price to match your job.
Concrete for a 3×20 sidewalk by thickness
| Thickness | Concrete to order | 80 lb bags | Material cost |
|---|---|---|---|
| 4″ (standard) | 0.81 yd³ | 37 | $130 |
| 5″ | 1.02 yd³ | 46 | $163 |
| 6″ | 1.22 yd³ | 55 | $196 |
Material cost at $160/yd³ ready-mix, before delivery fees. Cost data updated June 2026.
Common questions
How many yards of concrete for a 3x20 sidewalk?
A 3x20 sidewalk at 4 inches thick needs about 0.74 cubic yards before waste. Add 5-10% extra so you don't come up short. Change the thickness in the calculator above to see how it affects the total.
How many bags of concrete for a 3x20 sidewalk?
At 4 inches thick that's roughly 37 eighty-pound bags with a 10% allowance. Past about 1 cubic yard (around 45 bags), ready-mix delivery is usually cheaper and far less work than mixing bags by hand.
What does a 3x20 sidewalk cost?
Material alone is a small share of the total. Installed, sidewalks this size run a wide range depending on thickness, finish, site prep, and region. Use the calculator's installed-cost range as a ballpark, then compare local quotes for a real price.