Cubic Feet Calculator

Cubic to Feet Calculator: Convert Any Volume to Cubic Feet

Our free cubic to feet calculator quickly converts just about any measurements to cubic feet. This cubic to feet calculator converts inches, yards, meters, centimeters and even square footage to cubic feet, so you don’t have to hunt down separate conversion factors every time. Let’s go through the formula step-by-step in plain English: the basic length by width by height calculation, converting cubic inches, converting from yards and metric units, going from square, how to calculate cubic feet and back, working with cylinders and odd-shaped rooms, and even calculating a total material cost once you know your volume.

What Is a Cubic Foot?

A cubic to feet calculator is the volume of a cube that measures 1 foot on each side. It is one foot wide, one foot tall, and one foot long, all at once. This is the standard volume unit in the United States and is what most home, garden, and shipping calculations are based on.

Behind the scenes, this definition is tied to a larger system of standard measurements, maintained in the United States by the National Institute of Standards and Technology (NIST). Their official guide for converting units (NIST Special Publication 811) describes how a cubic foot relates to inches, yards, and metric units. We have used the same guide for the conversion factors on this page, so every number below is a real, verifiable source and not a rounded-off estimate.

Cubic Feet vs. Square Feet vs. Linear Feet

These three measurements sound similar, but each one describes something different. A linear foot only measures a single length. A square foot measures a flat area, using two dimensions. A cubic foot measures volume using three dimensions, which is why it’s the right unit any time depth or thickness actually matters.

Knowing which one you actually need matters. Ordering flooring only requires square footage, but ordering the topsoil to fill a raised garden bed requires cubic footage, since you also need to know how deep the soil goes. Mixing these up is one of the most common measuring mistakes people make before a project.

How to Calculate Cubic Feet: The Core Formula

Once you have the CFT calculator and all three measurements in feet, the basic formula for a rectangular space is

Cubic Feet = Length (ft) x Width (ft) x Height (ft)

Multiply the three dimensions together and you will have your total volume in cubic feet.

Example: Let’s say you are calculating cubic feet of a storage room that is 9 feet long, 6 feet wide and 4 feet tall.

Cubic Feet = 9 x 6 x 4 Cubic Feet = 216 cubic feet

That is the full volume of the room. The formula is good for anything rectangular a shipping crate, a raised garden bed, a closet or the cargo area of a moving truck. You just need the length, width and height in feet and this one formula does the rest.

If any of your measurements are in a different unit, such as inches or yards, convert each of those to feet first, and then multiply the same way. In the next few sections we will look at those conversions; this is where most people make mistakes in their calculations.

Converting Cubic Inches to Cubic Feet

Sometimes it’s easier to measure free cubic feet with a calculator or something in inches, especially for smaller things like boxes, drawers or coolers. If so, you will first calculate the volume in cubic inches and then convert to cubic feet using this formula:

Cubic Inches ÷ 1728 = Cubic Feet

A cubic foot is 12 inches on each side, so 12 * 12 * 12 is 1,728 cubic inches. That’s where that number is from. So dividing by 1,728 is simply a way of changing your answer from inches to feet.

Worked example: Let’s say you are measuring a storage box that is 22 inches long, 15 inches wide and 11 inches tall.

Cubic Inches = 22 * 15 * 11 = 3,630 cubic inches. Cubic Feet = 3,630 / 1,728 = 2.10 cu. ft.

This cubic to feet calculator is especially handy for smaller containers where you would be working in feet from the start and that would mean dealing with awkward decimals like 0.92 feet or 1.83 feet. Measure in inches, calculate in inches, then divide one time at the end.

Converting From Other Units to Cubic Feet

Cubic yards and metric units show up constantly, especially on material delivery quotes and international product listings. Here’s how each one converts to cubic feet:

There are two very good ways to solve a conversion like this. Or you can convert each dimension to feet individually and then multiply length x width x height. Or you can multiply your dimensions together in their original unit and convert the final total volume to cubic feet at the end. If you are consistent within each step, both methods will give you the same answer. So use whichever order is more natural for the numbers you are working with.

Square Feet to Cubic Feet, and Back Again

This is one of the most useful conversions for home projects, and it works in both directions.

Square Feet → Cubic Feet: Cubic Feet = Square Feet × Height (ft)

If you already know the area you’re covering and how deep the material needs to go, multiply the two together to get your total volume.

Worked example: You’re pouring a concrete slab across a 140 square foot patio at a depth of 4 inches (which equals 0.333 feet).

Cubic Feet = 140 × 0.333 ≈ 46.67 cubic feet

Cubic Feet → Square Feet: Square Feet = Cubic Feet ÷ Height (ft)

This CFT calculator is useful when you know a total volume and a fixed depth, and you want to figure out how much area that volume will actually cover. It only works when the height or depth is known or reasonably assumed.

Worked example: A supplier tells you a delivery contains 30 cubic feet of gravel, and you plan to spread it at a depth of 0.5 feet.

Square Feet = 30 ÷ 0.5 = 60 square feet

So that delivery will cover a 60-square-foot area at your chosen depth. This reverse direction rarely gets covered elsewhere, but it’s just as practical as the forward version, especially when you’re planning a delivery before you’ve finalized the exact area.

Cubic Feet for Cylinders and Irregular Spaces

Not everything is a nice rectangle. Round containers and oddly shaped rooms take a slightly different approach.

Cylinder: Cubic Feet = π x Radius² (ft) x Height (ft)

Work problem: The radius of a round planter is 1.5 feet and the height is 4 feet. Find the volume of the planter.

Cubic Feet = 3.14159 x 1.5² x 4 Cubic Feet = 3.14159 x 2.25 x 4 Cubic Feet ≈ 28.27 cubic feet

The easiest way is to divide it into 2 or more rectangular areas, compute them separately, and add them together. For an irregular space (like an L-shaped room).

Worked Example An L-shaped storage area is divided into a first section 10 ft.x8 ft.x3 ft., and a second section 5 ft.x4 ft.x3 ft.

240 cubic feet = 10 × 8 × 3 = Section 1. Section 2 = 5 × 4 × 3 = 60 cu ft Total = 240 + 60 = 300 cubic ft

The same split and add approach works for almost any irregular footprint as long as you can break it down into simple rectangular pieces first.

What Does a Cubic Foot Actually Look Like?

Numbers on a screen aren’t always real, so it helps to have some comparisons from everyday objects to finding cubic feet calculator. These are rough comparisons to sanity-check a result, not precise measurements.

• That’s like the size of a basketball, with a little bit of room to spare.
• Something like 1 to 1.5 cubic feet is the space taken up by a compact microwave oven.
• A small dorm room mini fridge is roughly 3 cubic feet.

If cubic to feet calculator result is way off from what a similar object would suggest, it’s a good sign to double check your measurements or your unit conversion before ordering materials or booking a shipment.

Calculating Cost per Cubic Foot

Then, with your total volume known, it’s a simple last step to determine cost. These two formulas cover the two directions:

Cost per Cubic Foot = Total Price / Total Cubic Feet Total Cost = Cubic Feet × Price per Cubic Foot

Worked example: You need 40 cubic feet of topsoil. Your supplier charges $3.25 per cubic foot.

Total Cost = 40 × $3.25 = $130 

Remember that the cubic feet to sq feet calculator in any such example is only a number you provide based on your own vendor quote. Material costs can vary greatly depending on your location, what you are producing and the time of year. It is better to check prices with your supplier rather than using a general average.

Conclusion

It shouldn’t take five different formulas over five different pages to convert between units. All the ways to convert cubic to feet in one place. The core length by width by height estimate cubic feet, cubic yards and metric units, the two-way relationship with square feet, cylinders and irregular spaces, and even total material cost.

Frequently Asked Questions

Q1. What’s the difference between cubic feet and square feet, and when do I need each? 

A figuring cubic feet calculator figures a flat area using length and width only. You’d use it for land size or flooring. You need cubic feet, which is a measurement of volume (adding height to the equation). This is what you need whenever depth or thickness is a factor (concrete, soil, mulch, storage space, etc.).

Q2. How do I convert cubic inches to cubic feet without a calculator?

Multiply the length, width and height in inches together to get your total cubic inches to cubic feet and then divide that number by 1,728 (12 × 12 × 12) since a cubic foot is exactly 1,728 cubic inches. For example, 3,456 cubic inches / 1,728 = exactly 2 cubic feet.

Q3. How do I find cubic feet for a cylinder or an irregularly shaped space?

For a cylinder, pi (about 3.14159) times the radius squared times the height, all in feet. For an irregular space like an L-shaped room, break the space into two or more simple rectangular areas and calculate the footage of each area separately, then add the results together for your total.

Q4. How do I convert square footage into cubic feet for concrete, mulch, or soil? 

Use the cubic feet to sq feet calculator to measure the square footage of the area, and multiply this by the depth or thickness of material you need (in feet, 4 inches is about 0.333 feet). A 150 square foot area at 0.333 feet deep will take about 50 cubic feet of material.

Q5. How many cubic feet are in a cubic yard or a cubic meter? 

One cubic yard equals 27 cubic feet. 1 cubic meter is about 35.31 cubic feet. These conversions can be helpful when you’re looking at quotes for bulk materials that are listed in different units.

Q6. How can I sanity check a cubic foot result without measuring again? 

Compare your result to a reference size you know. A compact microwave is roughly 1 to 1.5 cubic feet. A small mini fridge is roughly 3 cubic feet. If your volume calculation is way off from what a similar everyday object would suggest, double-check your measurements or the unit conversion you applied.