# How Much Does 1 Cubic Foot Of Concrete Weigh?

A cubic foot of concrete weighs about 150 lbs. when it’s solid. That’s about 4,500 lbs. per yard. However, a cubic foot of broken concrete only weighs around 75 lbs. It’s important to keep this in mind when calculating how much concrete weights because it gets lighter when it’s demolished. This is due to all the voids in between chunks. A cubic foot is a 3 dimensional volume measurement. 12 inches wide x 12 inches high x 12 inches deep makes a cubic foot. Fill that space up with solid concrete and you get 1 cubic foot of concrete weighing about 150 lbs. That’s about the size of a typical section of footing or pier.

The actual weight of concrete is determined by its density. This can vary a little depending on what sand, stone and cement you used in the mix. Generally speaking, the higher the concrete’s PSI, the more it weighs per cubic foot.

The individual weights of sand, cement, stone and water in a cubic foot of 3000 psi concrete are:

• 19 pounds of cement
• 58 pounds of sand
• 59 pounds of stone
• 14 pounds of water

These weights total 150 pounds per cubic foot of concrete. The mix is 3000 psi with 3/4 inch smooth stone and course mason sand. As you can see, stone is the heaviest followed by sand, cement and then water. If you mix a stronger concrete that’s 5000 psi, you’d decrease the sand and add more stone. This increases the weigh of the concrete per cubic foot by a few pounds.

Use the weight 150 lbs per cubic foot of concrete as a general guide. If you need to calculate an exact weight, you’ll have to use your concrete mix ratio and check the weight of each ingredient.

## What Effects Concrete’s Weight?

Concrete is made up of 4 main ingredients, sand, stone, cement and water. The amount you use of each ingredient is called the concrete mix ratio.

To make the standard 3000 psi concrete mix you need 1 part cement, 3 parts sand and 3 parts stone. In the construction industry this is referred to as a 1:3:3 mix. Water is the final ingredient. Use just enough to activate all the cement and not a drop more. Too much water will weaken a concrete batch.

Once you have the mix ratio figured out, you also have to select the right ingredients. I use 1/2″ to 1″ washed smooth stone to make my concrete. Order a 3/4″ stone which gives me a variety of sizes between 1/2″ and 1″.

I also use Portland brand cement and course mason sand. Any cement will due but I prefer Portland. Coarse sand produces a stronger, grittier concrete while smooth sand gives you a smoother finish.

When it’s time to mix the concrete, use fresh clean water.

The weight of a cubic yard of dry concrete is different than mixed. Dry concrete is a little heavier because water is the lightest ingredient in mixed concrete.

By varying the concrete mix ratio you produce heavier or lighter concrete.

Making stronger psi concrete means using more stone. When you use more stone that has the effect of using less sand. Since stone is heavier than sand, the weight per cubic foot goes up. The same is true in reverse. If you mix weaker concrete it means more sand and less stone. This reduces the concrete’s weight per cubic foot.

## Water Absorption

Another factor that effects how much a cubic foot of concrete weighs is water absorption.

An outdoor concrete slab can absorb a lot of water. But it will eventually dry out. When wet, a cubic foot of concrete weighs more than when it’s dry because of all the water it retains.

This is important to keep in mind when doing demolition work if you have to calculate the concrete’s weight. One cubic foot of concrete weighs approximately 150 pounds. And one cubic foot of demolished concrete weighs about 75 pounds. These are on average numbers. And they’re dry weights.

If you demolish a slab of concrete that’s wet, it can weigh pounds more per cubic foot. A single gallon of water weighs about 8 pounds. And a cubic foot of concrete can absorb at least that much. If you’re trying to calculate how much broken concrete you can put in your truck bed or a dumpster, make sure to factor in how much water the concrete’s holding.

Most full size pickups can carry around 1500 lbs in the bed which is 3/4 ton. In most areas, you can load up to 10 tons (20,000 pounds) of concrete into a 20 yard dumpster.

One cubic foot of concrete weighs about 150 pounds but one cubic yard of concrete weighs about 4,000 pounds. These are dry weights. You should always try to calculate the weight of your concrete before you rent a dumpster or start filling up a truck bed to make sure you don’t overload it.

## How Much Concrete Weighs Per Cubic Yard

Concrete weighs about 4050 pounds per cubic yard.

One cubic yard of concrete is equal to twenty seven (27) cubic feet of concrete. One cubic yard is equal to a box that’s 3 feet wide x 3 feet high x 3 feet deep. Inside that 3′ x 3′ x 3′ box fits 27 1′ x 1′ x 1′ boxes.

If you divide 4050 pounds by 27 cubic feet you get 150 pounds per cubic foot.

The individual weights of cement, sand, stone and water that make a cubic yard of 3000 psi concrete are:

• 517 pounds of cement (234 kg)
• 1560 pounds of sand (707 kg)
• 1600 pounds of stone (725 kg)
• 373 pounds of water (45 gallons)

Just as with a cubic foot of concrete, a cubic yard of concrete’s weight is effected by the concrete’s psi. The stronger the concrete, the more stone it has in relation to the other ingredients. This means it’ll be heavier because stone is the heaviest ingredient.

Water absorption also effects the weight of concrete. If your demolishing concrete that’s bone dry, it’ll be lighter than when it’s soaked with water. And concrete does absorb water like a sponge so this is a common issue to factor into your demolition work.

## How Much A Cubic Inch Of Concrete Weighs

Most small scale concrete projects are measured in inches and not feet. For example, a 2 inch thick dust cap or a 4 inch thick sidewalk slab.

One cubic inch of concrete is light, but the weight adds up quick when pouring an entire slab.

There are 1728 cubic inches in 1 cubic foot. Since 1 cubic foot of concrete weighs 150 lbs, you divide that by 1728 to get the weight of concrete per cubic inch. 150 / 1728 = .087 pounds or 1.39 oz.

A cubic inch of concrete weighs .087 pounds or 1.39 ounces when dry. This equals .039 kg.

A 5 gallon bucket has 1155 cubic inches of space inside. So if you’re scooping up small bits of concrete and transporting them to the truck or dumpster, that’s about 100 pounds per bucket full. 100.485 pounds to be exact.

An average size wheel barrow is 6 cubic foot or 10368 cubic inches. That’s about 900 pounds per wheel barrow full. 902.45 to be exact.

Understanding the weight of concrete per cubic inch can be helpful because small bits pack tighter into a container than large chunks.

As a general rule, about 1/2 a container full of demolished concrete is air. For example, a cubic foot of solid concrete is about 150 pounds. But a cubic foot of broken concrete is only around 75 pounds. However, a cubic foot of concrete filled with small pieces is much closer to the full 150 pounds per cubic foot because small bits of concrete pack together much tighter.

## How Much Does Concrete Weigh per Square Foot?

The weight of concrete per square foot depends on how thick the slab is. Square foot is a 2 dimensional measurement length x width. But to calculate weight you also have to factor is the 3rd dimension which is depth. This is where understanding the weight of concrete per cubic foot can help.

If the slab of concrete is 6 inches thick, divide 6 inches by 12 (1 ft.) This gives you the thickness of the slab in feet. 6 / 12 = .5 feet.

A cubic foot of concrete weighs 150 pounds. Multiply 150 pounds by .5 feet and you get 75 pounds for a square foot of concrete at 6 inches thick. And remember, this is dry weight. If the slab has absorbed water it’ll be heavier.

Now lets figure out the weight of a concrete slab per square foot that’s 4 inches thick.

First, divide 4 inches by 12 inches to get the thickness of the slab in feet. 4 / 12 = .333. Then multiply .333 x 150 lbs per cubic foot = 49.95 pounds per sq. ft. at 4 inches thick.

How much does a 2 inch thick slab of concrete weigh per square foot? This is the thickness of a typical dust cap.

2 / 12 = 0.166. 150 lbs X 0.166 = 24.9 pounds per square foot at 2 inches thick.

You can use this simple formula to calculate how much a square foot of concrete weighs at any thickness.

Note: Remember that the weight of concrete varies based on the concrete mix ratio used to make the concrete. The more psi concrete has, the heavier it typically weighs.

## What Does 4 Inches Of Concrete Weight Per Square Foot?

4 inches of concrete weighs 49.95 per square foot. This is based on concrete that’s 3000 psi. If the concrete has a higher psi, it’ll weigh more because more stone is used in the mix. This is also based on a fairly dry slab of concrete. If the slab is holding water it’ll weigh more per sq. ft. Water absorbs moisture like a sponge, especially when it’s not sealed, so keep this in mind.

4 Inches is the most common thickness for a residential concrete slab. Most concrete patios, porch tops, floors and sidewalks are 4 inches thick.

To figure out the weight of a 4 inch thick concrete slab you can use the formula shown above.

1. First, you have to convert 4 inches to feet. To do it, simply divide 12 inches by 4. 4 / 12 + .333.
2. Next, multiple .333 by the weight of concrete per cubic foot which is 150 lbs. .333 x 150 lbs. + 49.95 lbs.

To calculate the weight of an entire 4 inch thick concrete slab, simply multiply 49.95 x the surface area of the slab.

If you need to find the surface area of a slab, simply multiply it’s length x its width. For example, a 10′ x 10′ slab is 100 sq. ft. Multiply 100 sq. ft. x 49.95 lbs. and you get 4995 pounds.

## How To Calculate The Weight Of A Concrete Slab

You can use the formula above to calculate the weight of any concrete slab. All you need to know is the slabs thickness multiplied by it’s surface square footage.

For example, lets calculate the weight of a 20′ x 20′ x 4″ thick concrete patio.

1. Convert the thickness of the slab to feet by dividing 4 by 12. 4 / 12 = .33 ft thick.
2. Calculate the weight per sq. ft. 150 lbs per cubic foot X .33 equals 49.95 lbs per sq. ft.
3. Figure out the surface area of the slab by multiplying it’s length times its width. In this case 20′ x 20′ equals 400 sq. ft. of surface area.
4. Multiply the 400 sq. ft. surface area by 49.95 lbs. per sq. ft. to get the total weight of the slab. 400 x 49.95 + 19,980 lbs. dry.

Always remember that these weight calculations are rough averages. Vary the exact weight calculation based on the psi of the concrete used and how much water it’s holding.

## How To Calculate The Exact Weight Of Concrete Per Cubic Foot?

When I demolish a concrete slab and need to know exactly how much it weighs per square foot or cubic foot, the only way to know for sure is by weighing a sample.

I cut a small cube of the concrete with my concrete saw and weigh it. This will give you the exact weight per square foot or cubic foot of the slab at the time you do the weighing. Assuming the entire slab is made from the same psi concrete, which is normally is, you can calculate the total weight of the slab.

A sample will also take into account the slabs moisture content.

Keep in mind that no matter what you do, you won’t be able to calculate a slabs exact weight to the pound. Most slabs will vary a little in thickness and water absorption, but weighing a sample will get you closer to the true number.

A more exact weight can be helpful on large demo jobs because I’m normally limited to 20,000 pounds of concrete per dumpster. The closer I can come to an exact weight for the slab the better.

## Does Concrete Weigh More Per Cubic Foot When Wet?

I general,concrete weighs more per cubic foot when wet than when it’s dry. This is because much of the water used to mix the concrete evaporates out of the surface.

An average 1 cubic foot of 3000 psi concrete weighs 150 lbs. It includes 19 pounds of cement, 58 pounds of sand, 59 pounds of stone and 14 pounds of water. This is referred to as a 1:3:3 mix. One part cement, 3 parts sand and 3 parts stone.

When wet, the water accounts for 14 pounds of weight. But as the concrete cures it dries and evaporates much of that water. So yes, concrete weighs more per cubic foot when wet because it still contains all of its mix water.

Concrete never gets fully dry, but it’ll shed around 80% of its mix water during curing. This reduces it’s weight per square foot by about 11 pounds. However, concrete absorbs water like a sponge. So the weight of newly absorbed water can offset the water lost during curing.

## Summary: How Much 1 Cubic Foot Of Concrete Weighs

A cubic foot of concrete weighs about 150 lbs. when it’s solid. However, a cubic foot of broken concrete only weighs around 75 lbs. It’s important to keep this in mind when calculating weights because concrete gets a lot lighter when it’s demolished. This is due to all the voids in between chunks. A cubic foot is a 3 dimensional volume measurement. 12 inches wide x 12 inches high x 12 inches deep makes a cubic foot. Fill that space up with solid concrete and you get 1 cubic foot of concrete weighing about 150 lbs. That’s about the size of a typical section of footing or pier. The actual weight of concrete is determined by its density. This can vary a little depending on what sand, stone and cement you used in the mix. Generally speaking, the higher the concrete’s PSI, the more it weighs per cubic foot.

The individual weights of sand, cement, stone and water in a cubic foot of 3000 psi concrete are:

• 19 pounds of cement
• 58 pounds of sand
• 59 pounds of stone
• 14 pounds of water

These weights total 150 pounds per cubic foot of concrete. The mix is 3000 psi with 3/4 inch smooth stone and course mason sand. As you can see, stone is the heaviest followed by sand, cement and then water. If you mix a stronger concrete that’s 5000 psi, you’d decrease the sand and add more stone. This increases the weigh of the concrete per cubic foot by a few pounds.

Use the weight 150 lbs per cubic foot of concrete as a general guide. If you need to calculate an exact weight, you’ll have to use your concrete mix ratio and check the weight of each ingredient.

If you have any questions about concrete, email any time.