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How Many Concrete Bags Equal A Yard

Concrete is made from cement, sand and aggregate. When mixed with water it hardens to form concrete. The strength of the concrete is measured in pounds per square inch or psi. The psi of concrete is listed in a number on the bag. For example a Quikrete bag may say 3500 or 5000. That number refers to the psi strength of the concrete. The ingredient ratios can be adjusted to make different strength concrete. Concrete is most commonly sold by the cubic yard, but it’s also available in pre-mixed bags like Quikrete or Sakrete. A yard of concrete is a measurement of volume and not weight or strength. One cubic yard is equal to the volume of a cube with edges that are one yard (three feet) in length. In general about 90 x 40lb bags, 60 x 60lb bags, or 50 x 80lb concrete bags equal a yard.

Knowing how to calculate the amount of concrete you need for the job your doing is very important. There are lots of online calculators that can do it for you but it’s still good to know how to do it yourself just in case. We’ll cover the process to estimate how many concrete bags you need to do a job below.

Steps to Estimate Cubic Yards

The amount of concrete bags you need for a job is a measurement of volume, not weight or strength.

  • Length x Width x Height. 3 Measurements are needed to calculate the volume of whatever your working on. Measure the length, width and height of the slab, footing, wall etc. that needs concrete. If the project is complex or if multiple pours are needed, break things down into smaller pieces. Calculate the concrete needed for each individual piece and then add them all up at the end.
  • Convert Dimensions Into Feet. Conversion calculators make it easy to convert inches to feet, yards to feet or meters to feet. Unless of course your not working in the United States.
  • Multiply. The formula to calculate volume is simple. W x L x H.
  • Convert. Next convert cubic feet into cubic yards. This is simple too. Divide the cubic footage by 27 which gives you the cubic yards.
  • Estimate Pre-Mixed Bags. On average it will take 90 40lb bags, 60 60lb bags, or 45 80lb bags to fill one cubic yard of concrete.
  • Add 5%-10% additional material Always buys more concrete then you think you’ll need. This accounts for some waste or spills. It’s important to finish a concrete pour at one time before it sets and hardens.

Measuring Your Space

It’s just as important to know how many yards of concrete you need as it is to know how many concrete bags equal a yard.

To calculate this, you’ll need three numbers and a very simple calculation. Length x Width x Height. The length of the space you intend to fill, the width of that space, and the depth of concrete that you’re hoping to pour. Remember how many concrete bags equal a yard is a measurement of volume and not simple square footage.

Another way of looking at is is calculating the square footage surface area time the depth. For example a 10×10 patio has a surface area of 100 sq. ft. But to calculate the amount of concrete you need, that 100 sq. ft. must be multiplied by the depth.

The first two measurements, length and width, are easy to figure out. But the third is harder because it depends on what and how your building. For example that same 100 sq. ft. slab of concrete would probably be 4″ thick if it were a patio section but 6-8″ thick if it were part of a driveway. That could easily equal twice as many concrete bags.

Once you have all your numbers, convert them into inches. The reason you convert everything into inches is because you want all your measurements to be of the same denomination. It’s hard if you try to multiple inches with feet. Convert down into inches and then up into feet once the math is done.

Next, multiply the width x length x depth of the space that you want to fill with concrete. When you’ve got your answer, it will be in cubic inches.

Finally, divide the number that you came up with by 46,656 which gives you the cubic yards. When you know how many yards of concrete there is to fill it’s easy to figure out how many bags of concrete you need.

How Many Bags Of Concrete Do You Need?

Premixed bags of concrete are great for small to medium sized projects. Quikrete come in 40 pound, 60 pound, or 80 pound bags in a variety of strengths and mixes. Mixing bags on site is easy with basic tools like tray, wheel barrow, hoe and shovel. Or you can use a powered cement mixer.

The great thing about pre-mixed bags is that you can buy almost exactly what you need with very little waste. Buying a concrete truck can be expensive, especially if you don;t need a whole truck because most companies have small delivery charges.

Calculating bags is easy if you use the chart we’ve created below. First, calculate the amount of concrete you need. Then the size Quikrete bag you want to use. Finally, the chart will tell you how many bags you need.

This table shows the number of pre-mixed Quikrete bags of concrete needed per cubic yard.
Bag Size Pre-mix Quikrete Concrete Bags Needed to Fill
1/4 cu yd 1/2 cu yd 3/4 cu yd 1 cu yd
40 lb bags 23 45 68 90
60 lb bags 15 30 45 60
80 lb bags 14 25 36 50

How to Estimate Concrete Costs

Ready-mix concrete bags cost around $5 per 80 lb. bag. That works out to around $125 bucks per yard plus tax and delivery. Prices will vary based on the mix you use and where you buy it.

You should also calculate the cost of tools if you don’t have them already. Here’s a small list of what you’ll need.

  • Mixing Tray. You’ll need something to mix the concrete in if your doing the work by hand. A mixing tray costs around $15.
  • Wheelbarrow. You can mix in the wheelbarrow instead of a tray. I prefer it because it makes pouring the concrete into holes and footings easier. A decent wheelbarrow is around $50-$75.
  • Power Mixer. You can rent one by the day for around $50. They make mixing concrete much easier but you still need a wheelbarrow to move the concrete around the job site.
  • Hand Tools. Things like a shovel, how, trowel, edger, broom, float, etc. Buy basic concrete tools to suite the work your doing. You can buy everything you need for under $100.
Average Price Of Quikrete Concrete.
Total Price: $125 – $150 per cu yd
40 lb bags: $2.50 – $5 per bag
60 lb bags: $3 – $6 per bag
80 lb bags: $4.50 – $7 per bag

The national average total cost to build a concrete slab is $10 – $20 per square foot. Keep in mind that in addition to the cost of the concrete itself, there are also labor costs for preparing the area, pouring the concrete, and finish work. You can save a lot if your able to DIY a concrete project.

A simple broom finish is on the low end of the price range, while a decorative finish with coloring and stamps will be on the high end. Get an estimate from a local mason for a more accurate estimate.

The Weight of Concrete

Concrete weighs about 150lbs per cubic foot. And one cubic yard is 27 cubic feet of concrete. That equals about 4,056 pounds per cubic yard. When you dive this number by the weight of your bag it gives you a rough idea of how many concrete bags equal a yard. For example 4,056 divided by 80 equals 50.7.

This isn’t totally accurate because the concrete bag is measured in dry weight and not mixed weight. When you mix concrete you add water and that water has weight. But it’s still a good way to calculate a rough number of bags.

Round up whenever you get a fraction or decimal number. It’s more important to complete the job in a single pour than it is to get exactly the right amount of bags.

Always buy a bit more concrete than you think you’ll need. I like to add 10%.

Summary: How Many Concrete Bags Equal A Yard

Concrete is made from cement, sand and aggregate. When mixed with water it hardens to form concrete. The strength of the concrete is measured in pounds per square inch or psi. The psi of concrete is listed in a number on the bag. For example a Quikrete bag may say 3500 or 5000. That number refers to the psi strength of the concrete. The ingredient ratios can be adjusted to make different strength concrete. Concrete is most commonly sold by the cubic yard, but it’s also available in pre-mixed bags like Quikrete or Sakrete. A yard of concrete is a measurement of volume and not weight or strength. One cubic yard is equal to the volume of a cube with edges that are one yard (three feet) in length. In general about 90 x 40lb bags, 60 x 60lb bags, or 50 x 80lb concrete bags equal a yard.

Knowing how to calculate the amount of concrete you need for the job your doing is very important. There are lots of online calculators that can do it for you but it’s still good to know how to do it yourself just in case. We’ll cover the process to estimate how many concrete bags you need to do a job below.

If you have any questions or comments e-mail us any time. We’d love to hear from you.

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