Cubic yards = (length ft × width ft × thickness ft) / 27. There are 27 cubic feet in 1 cubic yard. Convert thickness from inches to feet by dividing by 12.

How many bags equal one cubic yard?

60 lb bag = 0.45 cu ft, so 60 / 0.45 = 60 bags per cubic yard. 80 lb bag = 0.60 cu ft, so 27 / 0.60 = 45 bags per cubic yard. Always round up.

Bags or ready-mix delivery — which is cheaper?

Under ~1 cubic yard: bags are more economical and reduce waste. Over 1 cubic yard: ready-mix delivery (typically requires 1-yard minimum + short-load fee) is faster, more uniform, and usually cheaper per yard. Many suppliers charge a minimum fee under 3 yards.

What thickness for common projects?

Sidewalk: 4 inches · Driveway (residential): 4-5 inches · Driveway (heavy vehicles): 6 inches · Garage slab: 4-6 inches · Footing: 8-12 inches depending on soil. Local codes may require more — verify before pouring.

Real pours always have spillage, form bulge from hydraulic pressure, and uneven subgrade. 10% is the rule-of-thumb minimum. Add more (15-20%) for footings poured on uneven ground or any irregular shape.

Concrete Volume Calculator

Home & DIY· 5 tools

Free concrete calculator for slabs, sidewalks, patios, and footings. Enter length, width, and thickness to get cubic yards (the standard ready-mix delivery unit) plus the equivalent count of 60 lb and 80 lb premixed bags. Default 10% waste covers spillage, uneven subgrade, and form bulge — bump higher for irregular pours.

Length (ft)

Width (ft)

Thickness (in)

Sidewalk 4in · Driveway 4-5in · Heavy 6in · Footings 8-12in

Waste factor (%)

Formula · cu yd = (L ft × W ft × T ft) / 27

Bag yields · 60 lb = 0.45 cu ft · 80 lb = 0.60 cu ft

Round bag count UP. Ready-mix delivery typically has a 1-yard minimum + short-load fee.

Concrete needed

1.36 cu yd

36.7 cu ft

60 lb bags82 bags

80 lb bags62 bags

Frequently Asked Questions

References

Quikrete Concrete Calculator Reference — Quikrete

Related Tools

Lumber Board Foot Calculator
Calculate board feet from lumber dimensions. Board foot = (thickness in × width in × length in) / 144. Add price per board foot for total cost.
Carpet & Flooring Calculator
Calculate carpet, hardwood, laminate, or tile flooring needed by room size. Includes 10% waste factor and converts to square yards plus optional total cost.
Wallpaper Roll Calculator
Calculate wallpaper rolls needed by wall size minus doors and windows. Includes 15% pattern-match waste and supports single-roll or double-roll formats.

Frequently Asked Questions

References and sources

Related Tools