Daily utilities

Concrete Calculator

Use OmniCalc's concrete calculator to estimate concrete needs in cubic yards, cubic feet, and approximate bag counts for common project shapes.

Concrete calculator

Estimate concrete volume for slabs, footings, and post holes.

Use this to estimate concrete in cubic yards, cubic feet, and approximate bag counts for common home-project shapes before ordering material.

Bag counts are rough planning estimates using about 0.6 ft³ per 80 lb bag and 0.45 ft³ per 60 lb bag.

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Why this result matters

What this calculator helps you answer

A practical home-project estimator for common concrete shapes that turns dimensions into ready-mix and bag-planning outputs. Use the tool above to enter a few clear inputs and get a practical answer you can use right away.

This concrete calculator helps homeowners, DIY builders, and contractors estimate how much concrete they need before ordering ready-mix or buying bags. It supports common shapes like slabs, footings, and post holes, and it adds simple bag-count views so small jobs are easier to plan.

Formula and method

How the calculation works

The calculator estimates raw concrete volume from the selected project shape, adds waste allowance, converts the result into cubic yards and cubic feet, and then estimates approximate bag counts using common bag-yield assumptions.

Example

Example slab estimate

If a slab is 20 feet by 10 feet, 4 inches deep, with 10% waste allowance, the calculator estimates total concrete needed in cubic yards, cubic feet, and approximate bag counts.

FAQ

Common questions about this calculator.

Short answers to the questions people often ask before or after using the tool.

Question

Why show cubic yards and bag counts?

Ready-mix concrete is often ordered by cubic yard, while smaller projects are often bought in bags. Showing both helps people choose the right buying method.

Question

Why include a waste allowance?

Real projects often need extra material for spillage, uneven grades, form irregularities, and practical job-site losses.

Question

Can this calculate post-hole concrete too?

Yes. The post-hole mode estimates cylindrical hole volume based on diameter, depth, and hole count.

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