You are watching: How many cubic feet in a bag of concrete

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## How to Calculate how Much Concrete i Need

The very first thing you must do is relax. It really ain’t that hard. Don’t let terms choose “cubic feet” and also “yield” and also “density” stroked nerves you. There room basically 2 steps. The an initial step is figuring the volume of the an are you want to fill. It no make any type of difference if you want to to fill it with concrete or vanilla ice cream cream. Volume is volume. Due to the fact that of the amount of concrete essential for most work it is usually simplest to number the volume in cubic feet. If your project is huge enough to calculation the volume in cubic yards instead of feet, speak to a prepared mix concrete truck. As soon as you hear “cubic” think ice cream cube. An ice cream cube usually has three sides (at least the people you do in the trays in your freezer at home do). The method to discover the volume the a cube is come multiple all three sides. If her cube to be a perfect cube and it to be 2 feet large and 2 feet long and also 2 feet deep, the volume would be 8 cubic feet. Concrete slabs space usually no perfect cubes for this reason the math is a small different. If you to be going to pour a slab the was 2 feet broad and 2 feet lengthy it would certainly not most likely be 2 feet deep. It could be 4” deep i m sorry is a regular depth because that a concrete slab. So currently the equation looks choose this: 2’ x 2’x 4”. The problem is you have to get whatever into the same units; you can’t multiple feet through inches. This is wherein folks gain hung up however it’s actually quite easy. Just multiple 2 x 2 x 4 ÷ 12. The prize is 1.3 cubic feet.

If you are filling a round hole in the ground to set a post or mail box, the calculation for volume is different than a cube or rectangle. The formula because that the volume that a round hole is *pi r2 *x depth. Or 3.14 x radius x radius x depth. The radius is half the broad of the hole. Unless you are doing a monster feet it can be most basic to do this every in inches. If her hole is 36” deep and 10” wide, the calculation is 3.14 x 5 x 5 x 36 ÷ 1728. This offers you 1.6 cubic feet. If you forget the 1728 it is just 12” x 12” x 12” or the number of cubic customs in a cubic foot.

So now that we recognize the volume the second step is to calculate how countless bags the concrete it will take to fill the hole. Top top the bag it will tell you how many cubic feet the bag will certainly fill. This is the “yield”. The yield on one 80 lb bag is around 6/10 (.6) cubic feet. If you take the example over of 1.6 cubic feet, the calculation would certainly be :

1.6 ÷ .6. = 2.7 bags

If you take place to it is in enthralled v math calculations I provide the adhering to information on how to calculation the yield that I stated was .6 cubic feet for an 80 lb bag. The an initial thing you need to know is the “density” the the concrete. If I offer you a crate filled v concrete that procedures 12” x 12” x 12” (or 1 cubic foot), how much do you think it will weight? walk ahead and take a guess- virtually everyone it s okay it wrong. The price is 145 lbs. (If it was filled through beer it would weigh 64 lbs.) This method the “density” that concrete is about 145 lbs per cubic foot. Currently that we have actually that information we deserve to calculate the yield. Include up both the dry product in the bag (80 lbs) and the water that takes to mix it up (1 gallon i m sorry weighs 8.3 lbs) for a complete weight the 88.3 lbs. Then division the complete weight by the density of the concrete.

88 ÷ 145 = .60 cubic feet.

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There is one technique for calculating the variety of bags compelled which is also easier. We have currently done the mathematics for girlfriend on concrete and also a variety of other products. Visit our calculators page before your following project. Determine exactly how much you require from home, the save aisle or native the jobsite.