When mixing concrete or mortar, selecting the correct mix ratio for your specific application is crucial. Get it wrong and your project could crack, crumble or fail to stand the test of time. But get it right and you’ll create a strong, durable and reliable finish that will support your project for years to come. 

The right ratio not only improves strength but also makes the mix easier to work with, helping you save effort and money in the long run. Here at Erris Concrete, we’ve put together this handy guide to explain mix ratios in simple terms and help you choose the one that’s best for your job.

What is a mix ratio? 

A mix ratio refers to the amount of each component required to make concrete. Essentially, it’s the concrete recipe and sets out what parts of cement, sand and aggregate are needed. For example, a 1:2:4 mix is:

• 1 part cement 
• 2 parts sand 
• 4 parts aggregate

The parts are not measured by exact weight, but by consistent volumes. The key is to use the same size container for each part so the ratio stays accurate. If you start with a bucket for cement, use that same bucket for sand and aggregate, too. 

This simple approach makes it easier to scale the mix up or down while keeping the proportions balanced, ensuring your concrete performs as expected every time.

Why is the mix ratio important?

The mix ratio you choose will affect several things, such as: 

• Strength: Too much sand or aggregate makes the mix weaker; too much cement makes it brittle.
• Workability: You need the mix to be workable — too stiff and it’s hard to place, too wet and it loses strength.
• Durability: Especially outdoors, your concrete must resist weather, moisture variation and wear.
• Cost: Cement is the most expensive component; overusing it is wasteful.

Also, the water-to-cement ratio (how much water you add) is nearly as important. Too much water reduces strength. The ideal is just enough to make the mix workable without being sloppy. 

What are common cement mix ratios?

Several common cement mix ratios are widely used in construction, each suited to different jobs and levels of strength required. Remember, the numbers represent parts by volume of each ingredient:

• The first number is always cement
• The second number is sand
• The third number is gravel or coarse aggregate (for concrete)

For mortar, which doesn’t use gravel, only two numbers are shown (cement and sand).

• 1:2:4 mix is a versatile, general-purpose concrete suitable for paths, slabs and everyday domestic projects.
• 1:1.5:3 mix produces a stronger, more durable concrete, often chosen for driveways, garage floors or shed bases that need to withstand heavier loads.
• 1:3:6 mix is a leaner, lower-strength option, useful for mass concrete or areas that don’t carry significant weight.
• 1:2 mix is a traditional mortar made with sand and cement only, ideal for laying bricks and blocks.

These ratios act as a guide, helping you achieve the right balance of strength, durability and workability for your specific project. Choosing carefully means you’ll avoid over-engineering, save on materials and still get reliable results.

Get in touch today

If you are looking for ready-mixed concrete, we are here to help. Get in touch to discuss your requirements.