How to measure and calculate the volume of concrete you need

A practical guide to help you order the right amount.

When it comes to concrete, precision matters. Over-ordering costs you money, while under-ordering can delay your project and lead to additional delivery charges. At McHugh Concrete, we help you get it right the first time and you can always give us a call to help you through the process.

This practical guide walks you through how to accurately measure and calculate the volume of concrete your project needs.

Step 1: Understand what you’re pouring

Before diving into calculations, get clear on what you’re working with. Ask yourself:

What shape is the area? (Rectangular, circular, post holes, etc.)
What are the exact dimensions?
Is the depth consistent?

Different projects may require different approaches – so knowing your job type is key.

Step 2: Use the correct formula

Concrete is measured in cubic metres (m³). Use the formula that fits your project type:

For rectangular or square slabs (e.g. patios, driveways):

Volume = Length × Width × Depth

Example:

A driveway that’s 6m long, 3m wide, and 0.15m deep: 6 × 3 × 0.15 = 2.7m³

For circular slabs (e.g. bases, pads):

Volume = ? × Radius² × Depth (Use 3.14 for ?)

Example:

A circular base with a diameter of 3m and depth of 0.2m:

Radius = 1.5m (half the diameter)
Volume = 3.14 × 1.5² × 0.2 = 1.41m³

For post holes:

Volume = ? × Radius² × Depth × Number of Holes

Example:

10 holes, each 0.2m in diameter and 0.6m deep:

Radius = 0.1m
Volume = 3.14 × 0.1² × 0.6 × 10 = 0.19m³

Step 3: Add a buffer

Once you’ve calculated the base volume, we recommend adding 5–10% extra to allow for:

Spillage
Over-excavation
Slight changes in depth or formwork size

Tip: If your total volume is 2.7m³, ordering 2.9–3.0m³ ensures you won’t come up short.

Step 4: Use our free concrete volume calculator

Not sure about doing the maths yourself? We’ve got you covered.

Use the McHugh Concrete Volume Calculator to get instant, accurate results:

Just enter your dimensions and it will calculate how much concrete you need.

Step 5: Get expert help if needed

If your project has unusual shapes or depth variations, don’t guess. Contact our team at McHugh Concrete and we’ll help walk you through the best approach. We’ve helped thousands of customers pour successfully and efficiently.

To give you some peace of mind when ordering, our Volumetric Concrete lorries deliver the exact amount of concrete you require, so if you need a little more or less concrete we’ve got it covered, and you will only be charged for what you use.