How much concrete do I need for a 3×20 sidewalk?
≈ 0.74 cubic yards
That’s about 34 bags of 80-lb concrete mix (or 45 60-lb bags) for a 3×20 area at 4″ thick.
A 3 ft × 20 ft sidewalk is 60 square feet. Poured at the standard 4-inch slab thickness, that’s 20.0 cubic feet of concrete — about 0.74 cubic yards.
| Area | 60 sq ft |
| Thickness | 4 in |
| Volume | 0.74 cu yd (20.0 cu ft) |
| 80-lb bags | 34 bags |
| 60-lb bags | 45 bags |
Tip: buy ~10% extra for spillage and uneven subgrade. For a thicker pour (driveways are often 5–6″), use the calculator to adjust.
Change the size → open the concrete calculatorGrab the supplies
Don’t forget — your supply list
Everything a job like this needs. Grab it in one trip.
Where do you shop?
As an affiliate, Clearly may earn from qualifying purchases — at no extra cost to you.