Concrete footing are almost always circular and a cardboard tube is installed to ensure the exact dimensions for the hole are right, and to make the final footing look great. Generally, 2 to 3 bags of concrete are needed per footing depending on how deep the footing needs to be. But, in this article I will explain how to calculate exactly how many bags of concrete you will need for concrete footings.
In general, first calculate to volume of the concrete footings (length * width * height). Then calculate how many bags of concrete it is. For example, a 60 lb bag of concrete will fills half a cubic foot (0.45 cu feet).
If you live in a cooler climate concrete footings need to be deeper, as concrete footings need to go deeper than the snow line to be structurally sound. The exact depth varies based on where you live, you should contact your local code compliance office. They can advise you of the exact dimensions your concrete footings need to be, after that you can use these dimensions to calculate exactly how much concrete you will need for your concrete footings using the instructions below.
Concrete Footings Estimator / Calculator
Concrete footings are very easy to fill yourself because the volume of concrete is quite low, and getting the concrete into the footings holes is very straightforward. Before installing concrete footings into the ground you should check with your local code compliance office, they can advise what dimensions your concrete footings need to be. Once you know that you can calculate the amount of concrete you will need using the instructions below.
Overall, calculate the volume of the concrete footings. To do multiply the width by the length by the height. Say, your concrete footings are 1 ft by 1 fit by 1.5 ft. The volume is 1 * 1 * 1.5 = 1.5 cu ft of concrete per footing. You then calculate how many bags of concrete, explained below.
The number of bags you will need depends on the size of the bag. Here’s a list of the different sized bags of concrete:
- 90 lb bag = fills 0.68 cu feet
- 80 lb bag = fills 0.60 cu feet
- 60 lb bag = fills 0.45 cu feet
- 50 lb bag = fills 0.375 cu feet
- 40 lb bag = fills 0.30 cu feet
Therefore, if the store sells 60 pounds bags you should divide the volume by the number of cubic feet a bag fills. For example, if the footings are 1.5 cu ft in volume, and the bags are sold in 60 lbs, which fills 0.45 cu ft, you divide 1.5 by 0.45 = 3.33 bags. Concrete is sold in full bags so you need to get 4 bags rather than 3.33 bags.
How to Calculate How Much Concrete Is Needed
To know how much concrete you need to fill an area, you need to know the volume of the area you are filling. Below is how to calculate that, and then how to use that number to calculate how much concrete you need.
As a general rule, calculate the volume of the area to be filled with concrete, then divide that by the volume the concrete bag fills. For example, a 60 lb bag of concrete fills 0.45 cubic feet. Below, is a table that shows how many cubic feet each sized concrete bag fills.
Here is a table that shows how many cubic feet a bag of concrete mags. Using that number you simply divide the volume of the area you are filling by the number of cubic feet of concrete the bag makes. This varies based on the size of bag that is available, or that you prefer:
| Size of bag | Cubic feet made per bag | Number of bags for 10 cubic feet |
| 90 lb bag | 0.68 cu feet | 14.7 bags (15 bags total) |
| 80 lb bag | 0.60 cu feet | 16.6 bags (17 bags total) |
| 60 lb bag | 0.45 cu feet | 22.2 bags (23 bags total) |
| 50 lb bag | 0.375 cu feet | 26.6 bags (27 bags total) |
| 40 lb bag | 0.30 cu feet | 33.3 bags (34 bags total) |
The number of bags for 10 cubic feet is calculated by dividing 10 by the number of cubic feet per bag.
90 lb bag = 0.68 cubic feet. 10 cubic feet divided by 0.68 = 10 / 0.68 = 14.7
80 lb bag = 0.60 cubic feet. 10 cubic feet divided by 0.68 = 10 / 0.68 = 16.6
On the bag of concrete you are buying it will also state this number. So, you can go to the store with the volume of the footings, and use that in store to calculate the number of bags you need. Or, online double check how much concrete each bag makes.
For example, this calculator from well known concrete and mortar brand Quikrete allows you to input the area in square feet and it tell you how many of each sized bag you will need. Give it a whirl to double check you got the right number of bags.
Amount of labor in hours calculation
Calculating how much labor it will take to mix and and install concrete is very easy. On average, it takes 10 minutes per bag. This time includes mixing the bag in a wheelbarrow and applying it into a hole.
So, if you need 10 bags for a project it would take 100 minutes. Which is 1 hour and 40 minutes.
How to Calculate Cost of Concrete
When installing a wide range of things around a home or building concrete is the go to, is easy to work with, and relatively inexpensive. But, say you want to fill a certain space with concrete, here’s how to calculate the total cost of the concrete you need to do it.
Overall, first calculate how many bags of concrete you need, then multiply the number concrete bags you need by the cost per bag. For example, if you need 5 bags of concrete, and each bag is $10. Then the total cost is $50. But, there are a few tools you may need to prepare and apply it.
Copyright protected content owner: ReadyToDIY.com and was initially posted on December 27, 2022.
Concrete has a different price depending on what type of concrete it is. Here are some example prices to give you a ball park figure:
| Type of concrete and bag size | Cost per bag |
| 50 lb – Fast setting | $5.29 per bag |
| 80 lb – High Early Strength Cement | $6.65 per bag |
| 93 lb – Portland Cement I and II | $13.75 per bag |
How to Calculate Cost of Concrete Project
There are a few tools and equipment you will need to mix and install concrete. It’s also good to get an idea of how long it would take, how much it would cost to get a contractor to do it. Below is a summary of each of the costs and how much it costs for each.
Overall, add the cost of the bags of concrete, the time it will take (labor), and the cost of tools and equipment which are: a wheelbarrow or concrete mixer, bubble level, a spade, hammer, the cardboard tubes or wood required. Below is how to estimate each of these costs.
Here’s a table that shows what the materials and equipment needed costs on average:
| Equipment or materials | Cost |
| Bags of concrete | Varies a lot based on the volume of the area to be filled. Refer above for how to calculate this. |
| Labor | Varies a lot based on the volume of the area to be filled. Around 10 minutes per bag of concrete. |
| Wheelbarrow | Wide range, second hand could be free all the way up to $100. |
| Shovel | Also a wide range, around $20 to $30 is reasonable. |
| Bubble level | $10 to $30 |
| Jug for water or garden hose | Likely you already have one of these |
| Hammer (optional) | $10 |
| Cardboard tubes (concrete footings) | $20 |
| Wood | Varies based on how much wood you need. $10 to $20 a foot for 2×4 planks |
Here’s a table that shows what each of the materials and equipment are used for.
Copyright article owner is ReadyToDiy.com for this article. This post was first published on December 27, 2022.
| Equipment or materials | What it’s used for |
| Bags of concrete | Powder for making wet concrete |
| Labor | Mixing the concrete, putting it into the hole, space, and leveling it off at the end.
10 minutes per bag of concrete. |
| Wheelbarrow | Used as a place to mix the concrete |
| Shovel | Used fr mixing the concrete, and putting it into a hole or space. |
| Bubble level | Checking the concrete is level. As well as, things like concrete tubes used for concrete footings. |
| Jug for water or garden hose | For adding water to the concrete mix |
| Hammer (optional) | For installing wood |
| Cardboard tubes (concrete footings) | Used to house the concrete. |
| Wood | Used for installing around the perimeter of a slab. Can be remove afterwards. |
Other Things to Consider When Estimating Concrete Project
Before mixing and pouring concrete there are a few things to consider. Overall, working with concrete is very straightforward but it’s important to ensure you’re aware of the ins and outs of estimating a concrete project, that way you can be sure you’re doing it right.
In general, begin by estimating the time it will take, and the cost of the concrete and equipment. If you prefer getting a contractor in you should add this cost in as well. There are also building codes that you need to find out for various concrete projects such as concrete footings.
Luckily, finding this info is very easy. You simply need to contact your local building codes office, and they can advise you what they are over the phone or email. As and example, they can tell you what dimensions the concrete footings need to be around a deck.
In general calculate the volume of your footings in cubic feet. To do that multiple depth/height by the width and then by the length ( l*w*h, length*width*height). After that calculate how many bags of concrete by dividing the volume, by the volume of concrete per bag.
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ReadyToDIY is the owner of this article. This post was published on December 27, 2022.