Concrete Calculator

Instantly calculate cubic yards, cubic meters, liters, and concrete bag counts. Supports both Imperial and Metric with automatic conversions.

Choose a concrete calculator

Imperial

Length (ft) Width (ft) Depth (in)

Metric

Length (m) Width (m) Depth (cm)

Imperial

Total Length (ft) Width (ft) Depth (in)

Metric

Total Length (m) Width (m) Depth (cm)

Imperial

Number of Holes Hole Diameter (in) Hole Depth (in)

Metric

Number of Holes Hole Diameter (cm) Hole Depth (cm)

Imperial

Number of Columns Diameter (in) Height (in)

Metric

Number of Columns Diameter (cm) Height (cm)

Imperial

Length (ft) Width (in) Height (in)

Metric

Length (m) Width (cm) Height (cm)

Imperial

Length (ft) Width (ft) Depth (in)

Metric

Length (m) Width (m) Depth (cm)

Mix Volume

Total Volume Volume Units

All mix outputs will use cubic yards.

Mix Ratio

Select a mix ratio

Water estimates use typical water–cement ratios for each mix.

How This Concrete Calculator Works

This tool instantly estimates how much concrete you need for slabs, pads, footings, post holes, curbs, cylinders, and custom mix ratios. Enter your dimensions in either Imperial or Metric and the calculator converts everything into cubic feet, cubic yards, cubic meters, liters, and bags automatically.

When to Use Each Mode

Slab Mode — patios, sidewalks, garage floors, shed pads.
Footing Mode — decks, retaining walls, structural beams.
Post Hole Mode — fence posts, pergolas, signs (with optional post subtraction).
Cylinder Mode — sonotubes, round piers, columns.
Curb Mode — edging, landscape borders, curb-and-gutter forms.
Bag Mode — when you already know the target volume.
Mix Ratio Mode — batching by recipe (1–2–3, 1–1.5–2.5, etc.) with water estimates.

Concrete Bag Yield Table (Most Accurate)

Bag Size	Approx. Yield (ft³)	Notes
40-lb	~0.30	Small repairs, patching
50-lb	~0.40	Common in Canada
60-lb	~0.45	General all-purpose
80-lb	~0.60	USA — same yield as 30-kg
66-lb / 30-kg	~0.60	Canada — same yield as 80-lb
20-kg	~0.40	Metric / common international
25-kg	~0.50	Metric / common international

Manufacturers adjust density so most premixed bags produce about 0.60 ft³ of mixed concrete. Yield, not bag weight, is what matters for estimating.

Formulas Used

Slabs: L × W × T
Footings: L × W × H
Post Holes / Cylinders: π × r² × depth
Curbs: L × W × H
Mix Ratio: divides total volume into cement, sand, aggregate, and water.

Common Mistakes to Avoid

Forgetting to convert inches to feet or centimeters to meters.
Not adding extra volume for waste, over-excavation, and uneven ground.
Ignoring minimum slab thickness for your climate and load.