Concrete Mix Calculator

  • AREA & DEPTH
  • VOLUME

Result

Wet Volume:

Wet Volume: cu yds

Dry Volume: cu yds

Material Needed

Cement Needed: 94lb bags

Cement Needed: cu yds

Sand Needed: cu yds

Gravel Needed: cu yds

Estimated Concrete Cost

$:

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.

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.