Updated for 2026

Concrete Calculator

Calculate concrete volume, number of bags, and estimated cost for slabs, footings, columns, and steps. Supports both metric and imperial measurements with rebar estimation and PDF export.

Select Shape

Dimensions
ImperialMetric

Length

Width

Depth / Thickness

Options

Waste Factor10%

Accounts for spillage, uneven surfaces, and over-excavation.

Bag Size

Price per Bag

Price per Cubic Yard (Ready-Mix)

$/yd³

Include Rebar Calculation

Enter your details above and click Calculate to see your results.

How It Works

Choose Your Shape

Select from rectangular slabs, circular slabs, footings, columns, or steps. Each shape uses the correct geometric formula to calculate volume accurately. For slabs, you enter length, width, and thickness. For circular shapes, enter the diameter. Columns use diameter and height, while steps require the number of steps, rise, run, and width. The calculator adapts its inputs to match your chosen shape, so you only enter what is needed.

Enter Dimensions

Input your measurements in either metric (metres) or imperial (feet) units. Toggle between unit systems at any time — the calculator handles all conversions automatically. Adjust the waste factor slider between 5% and 15% to account for spillage, uneven ground, or over-excavation. Select your preferred bag size and enter local pricing for accurate cost estimates. Optionally enable rebar calculation to determine reinforcement needs.

Get Results Instantly

Hit Calculate to see your concrete volume in cubic metres, cubic yards, and cubic feet. The results include the number of bags needed for your chosen bag size, total estimated weight, and a side-by-side cost comparison of bagged concrete versus ready-mix delivery. If you enabled rebar, you will also see the total rebar length, number of bars, and reinforcement weight. Export everything as a clean PDF for your records or to share with your contractor.

Why Use This Calculator

Accurate Estimates

Uses industry-standard concrete density (2,400 kg/m³) and accounts for waste factors from 5% to 15% depending on your project conditions.

Instant Results

Get volume, bag counts, weight, and cost comparisons in under a second. No sign-up required, no waiting for results.

Private & Secure

All calculations happen in your browser. We never store your project data on any server. Your dimensions stay on your device.

PDF Export

Download a clean, print-friendly PDF of your results including all inputs, volume breakdown, and cost comparison for your records.

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