When starting a concrete project, one of the most important calculations is determining how much concrete you need. We’ll walk through everything involved with buying bagged concrete to make one cubic yard, including the all-important question: how many 60 lb bags do you need?
With some simple math and manufacturer specs, we found that 60 bags of 60 lb concrete are required per cubic yard . But it’s helpful to understand exactly what a “cubic yard” entails along with some mixing and pouring fundamentals. Let’s start from the beginning!
What is a Cubic Yard of Concrete?
First things first – what does a “cubic yard” refer to when talking concrete? Essentially, it’s the volume that makes up a yard of concrete.
Visualizing a Cubic Yard
A cubic yard refers to a cube with the following dimensions:
- 3 feet wide
- 3 feet deep
- 3 feet high
So in total, a cubic yard equates to 27 cubic feet (3 x 3 x 3). It helps to visualize this shape to understand just how much concrete makes up a yard.
Here’s a cubic yard with a person for scale:
As you can see, a cubic yard is a substantial amount of concrete. Many smaller projects require just a fraction of a cubic yard. Yards are more commonly used for medium jobs like shed pads, or broken into multiple yards batches for major jobs.
Weight of a Cubic Yard of Concrete
Why is weight relevant for a cubic yard measurement? Because when determining bag numbers, it’s easiest to take the total weight of a yard and divide by the standard bag weight.
A cubic yard of concrete weighs roughly 3,600 to 4,000 lbs (1.6 to 1.8 metric tons). Those seem like odd numbers but there’s a reason – concrete density varies based on the type of aggregate used.
Heavier aggregates like gravel increase concrete weight over lighter aggregates like expanded clay. But 3,600 lbs (or ~1.6 tons) is a commonly used, reliable number for overall yardage weight.
Figuring Out How Many Bags You Need
Now that we know a few key specs around cubic yards, let’s look at the all-important question: how many 60 lb bags of concrete do you need to mix up a full yard?
Bag Specifications
Most standard bagged concrete comes in 60 lb bags like these:
As the name implies, these bags contain 60 lbs (27 kg) of dry concrete mix. This premixed combination contains cement, sand, gravel and other ingredients ready to mix with water.
Manufacturer Recommendations
Well-known brands like Quikrete and Sakrete actually provide guidance right on their packaging and websites specifying how many bags make up a yard.
Their experts recommend using 60 bags of 60 lb concrete per cubic yard . This number comes from test batches to optimize yield, strength, and the correct ratio of materials.
The manufacturers have dialed in the ideal bag-to-yard number so you don’t have to guess!
Doing the Math Yourself
Okay, but what if you wanted to validate the 60 number yourself? Simple math using the yardage weight confirms it.
Given:
- 1 cubic yard weighs ~3,600 lbs
- A 60 lb bag = 60 lbs
Dividing the total weight by the single bag weight gives us:
3,600 lbs / 60 lbs per bag = 60 bags
Adjusting for Different Bag Sizes
The 60 number is based on standard 60 lb bags. But you may come across 40, 70, or even 80 lb bags locally.
If using those, adjust the calculation:
- 40 lb bags – 90 bags per cubic yard
- 70 lb bags – ~51 bags per cubic yard
- 80 lb bags – 45 bags per cubic yard
Heavier bags require fewer to make up a yard. Do a quick check to ensure you have the right quantity!
Buying and Mixing the Concrete
Once you know the bags required, next up is actually getting and mixing the concrete…
Where to Buy Bags
You can pick up 60 lb bags of mix at any hardware store, home center, or building supply store. Top brands like Quikrete, Sakrete, and Home Depot’s Concrete Mix are all good options.
Bags run anywhere from $4-$7 each depending on quality and any delivery fees if ordering multiple yards. Shop around for deals from local and online retailers.
Mixing Tips and Techniques
Preparing 60-90 bags worth of concrete is no small task! Follow these tips for smooth and efficient mixing:
- Tools: Have a heavy duty wheelbarrow, extra buckets, a hose, shovel, and mixing tools like hoe or paddle ready
- Water: For 60 lb (27 kg) bags, use approximately 4-5 pints (1.9-2.4 liters) of water per bag
- Batches: Mix bags a few at a time instead of overloading your mixer and tools
- Paste: Before adding rock and aggregate, mix cement & water for a minute to form smooth paste
- Consistency: Add water gradually and mix thoroughly for ideal pouring consistency
Take rests to avoid burn out – mixing multiple yards is extremely labor intensive work!
Pouring and Finishing the Concrete
Once mixing is done, transport the wet concrete to your forms or project area. With wheelbarrows and helpers, carefully pour it into place.
- Make sure forms and any rebar or wire mesh is prepped and secured
- Pour concrete as close to its final position as possible
- Work efficiently – concrete begins curing once water is added
- Consolidate concrete with shovels or tools as you pour
- Screed and smooth newly poured slabs
Curing begins immediately so work quickly and have a finishing plan ready before mixing. Now relax and let the concrete do its thing!
FAQs
See below for answers to common questions about calculating and mixing up yards of concrete:
What concrete mix should I use?
For most general applications, use a standard 4000 PSI mix without any special aggregates added. Higher strength mixes over 5000 PSI are overkill for typical residential jobs.
Can I make multiple yards at once?
Yes, but prepare for VERY intensive mixing work. Limit batches to no more than 2 yards simultaneously depending on your available helpers, equipment, and energy!
How long does bagged concrete take to set?
Curing begins once water makes contact with the concrete and can take anywhere from several hours to days to fully cure and reach max strength. Avoid walking on it for a full 24 hours.
Is mixing by hand possible?
Technically yes but extremely arduous work. At minimum use a heavy duty wheelbarrow and have extra tools like hoes or paddles ready to mix with.
What about 80 lb or 40 lb bags?
As we saw earlier, alter the calculation based on different bag weights. 80 lb bags require 45 per yard, while 40 lb bags require 90 bags per yard. Adjust water amounts too.
There you have it – while mixing concrete is hard work, determining bag estimates is straightforward math.
Most manufacturers recommend 60 bags of standard 60 lb concrete per cubic yard . Remember to adjust if using heavier 80 lb bags or smaller 40 lb bags.
We covered everything from visualizing yards, to buying and mixing tips, to finishing and curing. Follow this advice and you’ll be well on your way to concrete pouring expertise!
