DIY Project Calculators
Tool Switcher: Concrete
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Volume before the pour

Concrete Calculator

Estimate slabs, bases, footings, foundation walls, columns, and circular pads in US or metric units—with bag yields, allowance, and optional bag cost.

  • Five common shapes
  • Ready-mix and bag totals
  • 50, 60, and 80 lb bags

Project calculator

Concrete Calculator

Estimate concrete volume, ready-mix yards, bags, and cost.

Select concrete shape

Methodology

From dimensions to bags

01

Calculate shape volume

Rectangular pours use length × width × thickness. Round pours use π × radius² × depth.

02

Multiply the quantity

Identical footings, pads, or columns are combined before the planning allowance is applied.

03

Add an allowance

The default 10% follows Sakrete’s planning guidance for uneven bases, spillage, and jobsite variation.

04

Round to whole bags

Recommended volume is divided by the selected product yield and rounded up to the next whole bag.

Worked example

A 10 × 6 ft slab, 4 inches thick

20 ft³exact volume

+

2 ft³10% allowance

=

37 bags80 lb mix at 0.60 ft³

Without the allowance, the same slab requires 34 whole 80 lb bags. Always confirm product yield and project requirements before ordering.

Buying guidance

Check the order before checkout.

Frequently asked questions

A second look at the estimate.

Why add a concrete allowance?

Uneven bases, form variation, spillage, and inaccessible remnants can increase the volume needed.

Can I use this for a concrete base or basement foundation?

For material volume, choose Slab for a flat base, Footing for a continuous foundation strip, or Wall for a foundation wall. It does not determine a basement’s dimensions, thickness, reinforcement, drainage, or structural requirements.

How do I estimate concrete bag cost?

Enter the price for one bag of the selected size. The Material Ticket multiplies it by the rounded-up bag count; ready-mix supplier pricing needs separate confirmation.

Can I compare bags and ready-mix?

Yes. The ticket shows cubic yards and metres alongside whole-bag estimates.

Related calculators

Keep planning the same project.

Sources and limitations

This calculator estimates material volume only. It does not determine slab thickness, reinforcement, mix strength, soil preparation, or structural suitability.

Last reviewed: August 21, 2026