Concrete Mix Calculator

Use our concrete mix calculator to find how much Portland cement, sand, and gravel you need for your mix.

How to Calculate a Concrete Mix

If you’re planning your next concrete project, then you need to consider whether to buy pre-mixed concrete, have a load of ready-mix delivered, or mix your own. If you choose to mix your own, then you can follow standard ratios to ensure you get a mix that’s durable and strong.

A good concrete mix is composed of four basic parts:

• Portland cement
• sand
• gravel or aggregate
• water

The proportions of each ingredient in the mix will determine how strong the resulting concrete is – this is referred to as compressive strength. These ratios are called the mix ratio.

The mix ratio for a standard M5 concrete is 1:5:10, and when mixed and poured correctly will yield concrete with a 725 psi compressive strength.

The parts of the ratio refer to the amount of Portland cement, sand, and aggregate needed, in order. So for this ratio, for every 1 part Portland cement, you’ll need 5 parts sand and 10 parts aggregate or gravel.

There are also additives that can be added to the mix to increase working time, reduce curing time, add color, and more.

Steps to Estimate Cement, Sand, and Gravel

You can calculate the amount of Portland cement, sand, and gravel needed for a concrete mix by following a few simple steps.

Step One: Calculate the Dry Volume

One important consideration when estimating a concrete mix is the difference between the wet and dry volume. When you measure a space and determine its volume in cubic yards, this is a wet volume, or rather, the amount of wet concrete needed to fill it in.

The dry volume of the mix is the volume of the dry ingredients before adding water. The dry mix actually consumes more volume before adding water due to all of the air – 54% more, in fact!

So, the first step to estimating materials is to calculate the dry volume. You can do that by multiplying the wet volume required by 54%.

dry volume = wet volume × 1.54

Step Two: Calculate the Percentages of Each Part

The second step is to calculate the percentage of each part in the mix. Start by adding up each part in the ratio to find the total number of parts.

For instance, for the M5 1:5:10 mix ratio, add up the cement, sand, and gravel parts like this:

1:5:10 mix -> 1 + 5 + 10 = 16 parts

So, in the M5 mix, there are 16 total parts.

Now, for each component in the mix, divide the number of parts by the total number of parts to find its percentage of the dry volume.

1 part cement -> 1/16 = 0.0625
5 parts sand -> 5/16 = 0.3125
10 parts gravel -> 10/16 = 0.625

So, the M5 mix is composed of 6.25% cement, 31.25% sand, and 62.5% gravel.

Step Three: Calculate the Volume of Each Component

Now, it’s time to calculate the volume of each component in the mix. Do this by multiplying the percentage of each one by the dry volume required.

Continuing the example using the M5 mix, multiply the percentage of cement, sand, and gravel by the dry volume required to find the volume of each needed for the mix.

This is the same process used to estimate materials for a mortar or grout mix.

Standard Concrete Mix Ratios

The table below shows the standard mix ratios for various grades of concrete.

Table showing the mix ratios of cement, sand, and aggregate for standard grades of concrete

Concrete Grade	Mix Ratio	Compressive Strength
M5	1 : 5 : 10	5 MPa (725 psi)
M7.5	1 : 4 : 8	7.5 MPa (1087 psi)
M10	1 : 3 : 6	10 MPa (1450 psi)
M15	1 : 2 : 4	15 MPa (2175 psi)
M20	1 : 1.5 : 3	20 MPa (2900 psi)
M25	1 : 1 : 2	25 MPa (3625 psi)