Concrete Mix Calculator

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

Find volume using our cubic yards calculator

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Total Concrete Volume

Wet Volume:
 
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Dry Volume:
 
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Material Needed

Cement Needed:
 
94lb bags
Cement Needed:
 
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Sand Needed:
 
cu yds
Gravel Needed:
 
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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.

The ratios of the basic ingredients for concrete can change with the application. Rougher, larger aggregate may be added for some projects that need extra strength, while more sand and finer aggregates may be needed for a countertop.

A good concrete mix is composed of four basic ingredients:

  • 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.

This is a formula you would follow for areas that need good compressive strength like a patio. However, for supports or driveways that will handle heavy trucks, you may need a formula that will yield concrete with a higher psi.

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!

When adding water, the mix will settle and shrink, taking less space overall. Because the liquid concrete is what you will be working with, you will need to adjust for this before mixing.

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.

For example, let’s calculate the amount of cement, sand, and gravel for the M5 mix to fill one cubic yard of space.

Start by calculating the dry volume of the mix.

dry volume = 1.0 × 1.54 = 1.54 cu yds

Recall the percentages for this mix are:

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

Now, multiply each of these percentages by the dry volume to find the volume of each one required for the mix.

cement -> 0.0625 × 1.54 = 0.09625 cu yds
5 parts sand -> 0.3125 = 0.48125 cu yds
10 parts gravel -> 0.625 × 1.54 = 0.9625 cu yds

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)

Water to Cement Ratio

The amount of water you add to your concrete mix is also important. Having a low water ratio can actually improve the strength of concrete, but can make it very hard to work with, which may impact final quality.

Likewise, adding too much water will end up making the final concrete too brittle. Therefore, you need to get the right mix of water to concrete.
Below is the maximum amount of water to concrete ratio recommended for each type.

Table showing the ratio of water to the mix of concrete
Concrete Mix Max Water Cement Ratio
M5 .60
M7.5 .60
M10 .60
M15 .50
M20 .45
M25 .40

Notice that as compressive strength goes up, the amount of water required goes down. To determine how much water you need for your project, you will use the following formula:

water/cement ratio × weight of the cement needed

One cubic yard of dry mix weighs roughly 3,600 pounds. Keep in mind that as you adjust the ratios, the weight may vary.

To find the water needed for 1 cubic yard of M5 dry mix, you would use this formula:

3,600 × .60 = 2,160 pounds of water

Each gallon of water weighs 8.34 lbs, so one cubic yard of M5 dry mix would require 259 gallons of water to complete.