If you're asking yourself "how much cement do I need for a specific concrete or mortar mix?" then this cement calculator, or Portland cement calculator, will help you with it. This calculator can also function as a mortar mix calculator or a cement bag calculator.
In this calculator, you will learn what cement is and what the difference between concrete and cement is. You will also learn how to calculate cement in terms of bags or any units of volume. As an added feature, you will also be able to calculate the amount of sand and gravel for any concrete mix. Keep on reading to start learning!
What is cement?
Cement is a reactive powder component that binds fine and coarse aggregates together with water. Water and cement react together and harden to form a durable yet brittle material. Cement is made out of pulverized and crush stones mixed with chemicals such as lime and calcium silicate.
Cement can be categorized into two main types depending on how it reacts with water. Hydraulic cement sets and hardens in the presence of water and remains durable and tough after hardening. On the other hand, non-hydraulic cement sets in a dry environment in the presence of carbon dioxide and tends to expand and deteriorate after setting, especially when exposed to water. Because of that, non-hydraulic cement is usually used for indoor purposes only.
In our modern construction industry, we now mostly use hydraulic cement for indoor and outdoor uses. Portland cement, particularly, is the most common hydraulic cement around the world, so, in this calculator, we focus mainly on Portland cement and its uses.
Different applications of cement
When talking about cement, the word concrete usually also comes into play. And though they might seem the same, they are indeed two different things. Concrete is a produced by mixing cement with water, fine aggregates like sand, and coarse aggregates like gravel. Cement binds everything together to form concrete.
On the other hand, by mixing just cement, sand, and water we create mortar. Mortar is used for joining together concrete blocks or bricks. Adding more water to a mortar mix makes it suitable for plastering concrete block walls. By adding water, we can make a thinner and smoother mix that can be troweled to finish a surface.
Cement is also used in making grout mixtures. We use grout to fill in the gaps between tiles and even between bricks. However, nowadays, we can already buy pre-mixed cementitious dry grout in bags for convenience. If you want to learn more about grout and would also love to know how to calculate the volume of grout needed for a tiling project, you can check our grout calculator.
How to calculate cement?
Since cement is usually used together with other construction materials like sand and gravel, we calculate its volume using a mix ratio. With mix ratios, we can tell how many components a concrete mix or mortar mix will need in terms of parts.
Mix ratios do not only help determine the amount of cement, sand, and gravel needed, it also tells us something about the strength and durability of the final product. The more cement we have in the mix, the stronger the product will be. Here are some of the common mix ratios of concrete and their corresponding compressive strengths and uses in construction:
(cement : sand : gravel)
|Mass concrete works|
|Mass concrete for foundations,
footings, and heavy walls
|General reinforced concrete columns,
beams, and slabs
|Precast and dense concrete works,
water-retaining structures, and piles
|Heavily-loaded reinforced concrete
column and long-span beams
Nowadays, we typically use a 1:2:4 mix ratio when building a reinforced concrete single-story house. As a nickname, we can call this mix M15 grade which comes from its corresponding 15 MPa compressive strength. If we want to build a 2-story house, we would need a stronger mix like the M20 grade mix, which follows a 1:1.5:3 mix ratio.
When calculating the amount of cement in a mix, it is worth knowing that the dry mix volume shrinks after adding water, decreasing its volume. Adding water to the dry mix makes the fine particles of cement glide into the sand and gravel mixture's void spaces.
The wet volume of concrete is what we usually get when obtaining the volume inside of a formwork. However, we need the concrete mix's dry volume to determine how much cement, sand, and gravel we need. We can approximate the concrete mix's dry volume by multiplying the wet volume by a value that engineers use, which ranges from
After determining the dry volume of the concrete we need, we can then use our preferred mix ratio to find how much cement we need for our project. In the next section of this text, we'll consider an example to understand further how to calculate cement.
How much cement do I need? - Sample calculation
Let's say we want to make a 5.0 MPa (725 psi) 20 cm x 20 cm x 20 cm concrete block using a steel mold we made in our steel plate weight calculator. By multiplying the dimensions of the concrete block steel mold, we obtain the wet volume of the concrete needed:
wet volume = 20 cm x 20 cm x 20 cm = 0.2 m x 0.2 m x 0.2 m =
Let's say we want to use a dry volume to wet volume ratio of
1.54:1. We can then find the dry volume by multiplying our calculated wet volume by 1.54, as shown below:
dry volume = wet volume * 1.54
dry volume = 0.008 m3 * 1.54 =
From the table in the previous section of this text, we need a mix ratio of 1:5:10 to make a 5.0 MPa (725 psi) concrete block. By adding the ratio's parts together, we obtain the total parts to be
1 + 5 + 10 =
16. Among these 16 parts, cement is one part of it, sand another 5 parts of it, and gravel the remaining 10 parts. We can also express this in the pie chart shown below:
To get each component's volume, we can multiply how many parts each of them make up by the total part of the dry mix:
volume of component = dry volume * part from total / total number of parts
which for each component:
volume of cement = 0.01232 m3 *
/ 16 =
0.00077 m3 ✔
volume of sand = 0.01232 m3 *
/ 16 =
volume of gravel = 0.01232 m3 *
/ 16 =
From our calculation above, we can now say that for us to make a small 5.0 MPa 20-cm cube of concrete block, we would need 0.00077 m3 of cement, 0.00385 m3 of sand, and 0.00770 m3 of gravel.
Please take note that calculating the cement in a mortar mix follows the same procedure as above. The only difference is that there won't be any gravel in the mix.
How to use our cement calculator?
Using our cement calculator is quite easy. The first thing you have to do is select which mix you want to make. After that, input the wet volume of the mix you need. We have already pre-entered a value for the dry volume to wet volume ratio, but you can still change it. Instantly, the calculated dry volume will be displayed. As usual, you can input the percentage of assumed wastage you might need depending on the worker's handling of the materials. After that, you will be given the total dry volume.
Next, select your preferred mix ratio to get the volumes of cement and sand for a mortar mix, and cement, sand, and gravel for a concrete mix. The weight of cement is also automatically calculated using a cement density of 1440 kg/m3 (90 lb/ft3) that you can change in the
advanced mode of our cement calculator.
Since you can get cement in bags, we have also added that feature in our cement calculator. Enter the weight of a bag of cement available in your area to calculate the number of bags to fit the cement's calculated weight.
If you want to estimate the material cost for the volume of mix you wish to make, you can also check it out in our calculator's
Want to learn more?
If you found our cement calculator informative and useful, perhaps you would also like to check our concrete column calculator to learn more about concrete and even about pre-mixed concrete.