Construction Toolkit

Concrete Calculator

Quickly size slabs, footings, or columns. Apply waste allowances, compare bagged versus ready-mix pricing, and export material totals.

Unit system

Rectangular slab with length × width × thickness. Ideal for driveways, patios, and basement floors.

Volume overview

Total volume

4.89 yd³

Metric volume

3.74 m³

Bags needed

295

Truck loads (8 yd³)

0.61

Cost estimate

Bagged concrete

$1917.50

Ready-mix delivery

$708.89

Ready-mix estimates exclude delivery surcharges. Adjust bag price for local supplier quotes.

Material breakdown

Approximate dry material masses based on standard mix ratios (1:2:3 cement:sand:aggregate).

Cement

1308 kg

Sand

2616 kg

Aggregate

4485 kg

How to estimate concrete

Gather shape dimensions, quantity, and waste allowance before ordering.

  1. Pick a shape

    Select a slab, footing, column, stair, curb, or custom form card.

  2. Enter dimensions

    Type length, width, and thickness or height. Use the unit dropdown to switch between feet and meters.

  3. Add to project

    Set the quantity and add the shape to the project list. Repeat for each pour or form.

  4. Review totals

    Adjust waste percentage and read the cubic yards, cubic meters, and bag counts before ordering.

Case study: Driveway with footings

A contractor needs to pour a driveway slab plus two pier footings for a carport post.

Slab
24 ft x 18 ft x 5 in
Footings
Two pads 2 ft x 2 ft x 12 in
Waste buffer
7%
  1. Model the slab

    Length, width, and thickness produce about 17.9 cubic yards for the main driveway.

  2. Add footings

    Two footing cards add 0.3 cubic yards.

  3. Apply waste

    With 7% waste the project total suggests ordering roughly 19.5 cubic yards.

Ordering decision

The team books a 20 cubic yard ready-mix delivery and keeps a short list of bag counts for contingency.

Concrete calculator FAQs

How much waste should I add?

Flat slabs often use 5% extra, while complex forms or hand mixing benefit from 8-10% buffer.

Can I mix units?

Yes. Switch each field between feet and meters; the totals show both cubic yards and cubic meters.

Does it support multiple shapes?

Add as many shapes as needed. The project list keeps volumes separate and totals them at the top.

Helpful resources

  • ACI concrete placement guidelines
  • Ready-mix ordering checklist
  • Rebar basics