Cubic Feet to Cubic Yards Converter

How do you convert cubic feet to cubic yards?

Divide the number of cubic feet by 27. One cubic yard is a cube 3 ft on each side, and 3 × 3 × 3 = 27 cubic feet.

Cubic yards = cubic feet ÷ 27

To convert back, multiply:

Cubic feet = cubic yards × 27

The converter above handles both directions and also gives cubic meters. A common mistake is dividing by 9 or by 3. Nine converts square feet to square yards (area), and 3 converts feet to yards (length). For volume it is always 27.

Cubic feet to cubic yards chart

Every value below is cubic feet ÷ 27, rounded to three decimals.

Cubic yards to cubic feet chart

Suppliers quote in yards, but bags and some tools use cubic feet. Multiply by 27.

How many cubic feet are in a yard of concrete?

A yard of concrete is 27 ft³, like any cubic yard. Bagged concrete is labeled by weight, so the yield per bag tells you how many bags make a yard. Using QUIKRETE’s published yields (the 90 lb bag is sold only in some regions):

The bags of concrete per yard page covers partial yards and waste.

Cubic feet in bags of mulch, soil and gravel

Landscape bags are usually labeled in cubic feet. Divide 27 by the bag size to see how many bags equal a bulk yard: 18 bags of 1.5 ft³, 13.5 bags of 2 ft³ or 9 bags of 3 ft³.

A 4 × 8 ft raised bed filled 12 in deep holds 32 ft³, which is 1.19 yd³. That is 16 bags of 2 ft³ or 22 bags of 1.5 ft³. The raised bed soil calculator does this for any bed.

To see what one bag covers, multiply its cubic feet by 12 and divide by the depth in inches. A 2 ft³ bag covers 12 ft² at 2 in or 8 ft² at 3 in; a 1.5 ft³ bag covers 9 ft² at 2 in or 6 ft² at 3 in. A 200 ft² bed at 3 in therefore needs 50 ft³: 25 bags of 2 ft³, or 1.85 yd³ in bulk.

Bagged mulch and soil are often compressed in the bag and fluff up when you open them, while bulk material settles after spreading. Either way, check coverage after the first few bags and adjust before you buy the rest, rather than relying only on the label.

Cubic feet, cubic yards and cubic meters

Outside the US, bulk materials are sold by the cubic meter or the tonne. Use these factors (rounded):

• 1 ft³ = 0.0283 m³, and 1 m³ = 35.31 ft³
• 1 yd³ = 0.7646 m³, and 1 m³ = 1.308 yd³
• 1 yd³ = 27 ft³ = 46,656 in³ (12 × 12 × 12 × 27)

If your quote is in tons rather than volume, use the tons to cubic yards converter, which needs the material’s density.

How much does a cubic foot of concrete weigh?

About 150 lb, the normal-weight value WSDOT uses for design (150 lb/ft³ plain, 155 lb/ft³ reinforced) and the one this site uses for wet-weight results. QUIKRETE states about 140 lb/ft³ for its bagged Concrete Mix, and FHWA gives about 140–155 lb/ft³ for normal-weight concrete.

In metric, 150 lb/ft³ is about 2,403 kg/m³ and 140 lb/ft³ is about 2,243 kg/m³. Weight is what limits you when moving cured pieces or hauling bags: a 10 ft³ pour is about three quarters of a ton of finished concrete. Even a 4 × 4 ft pad 4 in thick (5.33 ft³) weighs about 800 lb at 150 lb/ft³, so even a small pad is easier to pour where it will sit than to cast elsewhere and move into place later.

Why an 80 lb bag is not 80 lb of finished concrete per cubic foot

An 80 lb bag yields about 0.60 ft³ once mixed, so 1 ft³ takes 1.67 bags, or 2 whole bags. The dry mix plus water ends up near the 140 lb/ft³ density QUIKRETE quotes. Do not divide bag weight by density to estimate yield; use the yield printed on the bag.

Cubic feet formula for concrete shapes

Work out the volume in cubic feet, then divide by 27 if you need yards. All dimensions must be in feet first, so divide inches by 12.

• Slab, footing or wall: length × width × thickness. A wall 10 ft long, 3 ft high and 8 in thick is 10 × 3 × 0.667 = 20 ft³ (0.74 yd³).
• Round hole or tube: 3.1416 × radius² × depth. A 12 in tube 4 ft deep is 3.14 ft³; an 8 in tube 4 ft deep is 1.40 ft³; a 6 in tube 3 ft deep is 0.59 ft³.
• Post hole with a post in it: hole volume minus the post. A 10 in hole 3 ft deep is 1.64 ft³ empty and 1.38 ft³ with a 4×4 post (3.5 × 3.5 in actual) in it.
• Steps: add up each step as a block of width × run × its height above grade, plus the landing.

The Sonotube calculator, fence post concrete calculator and concrete steps calculator apply these formulas with the right inputs for each shape.

How many bags of concrete make 1 cubic foot?

Divide 1 by the bag yield, then round up. Using the QUIKRETE Concrete Mix yields:

For a single cubic foot you need at least two bags. Two 80 lb bags give 1.2 ft³ (0.2 ft³ to spare), and two 90 lb bags give 1.35 ft³ (0.35 ft³ to spare). A 3 × 3 ft pad 4 in thick is exactly 3 ft³, which is 5 bags of 80 lb or 7 bags of 60 lb. For bag counts on bigger jobs, the concrete bag calculator handles waste and mixed bag sizes.

Mixing bag sizes

If you already have a mix of bags, add their yields in cubic feet first. Twenty 80 lb bags plus ten 60 lb bags is 20 × 0.60 + 10 × 0.45 = 16.5 ft³, which is 0.61 yd³.

From cubic feet to a ready-mix order

Ready-mix is ordered in cubic yards, often in ¼ or ½ yard steps (ask your supplier). Convert your cubic feet, add the waste allowance, then round up once.

Going the other way, multiply the order by 27 to see the cubic feet you are paying for: ¾ yd³ is 20.25 ft³, 1¼ yd³ is 33.75 ft³ and 2½ yd³ is 67.5 ft³. Compare that with your measured volume to see how much margin the rounding left. The concrete yards calculator does the whole calculation from dimensions.

What does 1 cubic foot of concrete fill?

One cubic foot is a 12 × 12 × 12 in cube, or 0.037 yd³ (0.0283 m³). Spread flat, it covers 12 ft² at 1 in thick, so divide 12 by your thickness in inches:

• 2 in thick: 6 ft²
• 4 in thick: 3 ft²
• 6 in thick: 2 ft²

It fills a square hole 12 in on a side and 12 in deep, or about 1.8 ft of a 10 in round post hole (1.64 ft³ fills 3 ft). That makes 1 ft³ a useful mental unit: a 4 in slab takes one cubic foot for every 3 ft², so a 6 × 8 ft pad (48 ft²) needs 16 ft³, about 27 bags of 80 lb before waste.

When to use cubic feet and when to use cubic yards

Cubic feet suit small jobs and anything sold in bags: concrete mix, potting soil, bagged mulch and sand. Cubic yards suit bulk deliveries, where a supplier loads a truck. The break-even point is about where bag counts become impractical. One cubic yard is 45 bags of 80 lb concrete or 13.5 bags of 2 ft³ mulch.

A practical rule: do the measuring in feet and the volume in cubic feet, because the multiplication is easier to check. Convert to cubic yards only at the end, when you are ready to compare with a bulk quote or a ready-mix order. That keeps one division by 27 in the whole calculation and leaves fewer places for an error. Write the cubic feet down next to the yards on your order sheet, so anyone checking the delivery can follow the arithmetic.

Comparing a bag price with a bulk price

Turn both prices into the same unit before you compare. Divide the bag price by the bag’s cubic feet to get a price per cubic foot, then multiply by 27 for a price per cubic yard. That figure sits directly next to a bulk quote.

The bulk quote usually has extras the bag price does not: a delivery charge, and sometimes a small-load fee. Add those to the bulk total, then divide by the yards you are ordering. Bags have hidden costs too: trips to the store and, for concrete, lifting and mixing every bag. Over a yard of 80 lb concrete that is 45 bags, about 1.8 tons of dry mix.

Prices vary by region and season, so use your own quotes. The concrete price per yard page explains what goes into a ready-mix quote.

Cubic inches to cubic feet

Divide cubic inches by 1,728 (12 × 12 × 12) for cubic feet, or by 46,656 for cubic yards. 1,000 in³ is 0.579 ft³. A form 8 × 16 × 24 in holds 3,072 in³, which is 1.78 ft³, close to three 80 lb bags. A 6 × 6 × 6 in cube is 216 in³, exactly 0.125 ft³ or one eighth of a cubic foot, so eight of them fill one cubic foot.

Common mistakes when converting cubic feet to cubic yards

Most wrong orders come from mixing up length, area and volume units. Check these before you call a supplier.

• Dividing by 9 or 3 instead of 27. Nine square feet make a square yard, which is area, and 3 feet make a linear yard. 100 ft³ ÷ 9 gives 11.1 and ÷ 3 gives 33.3. The right answer is 3.70 yd³.
• Forgetting to convert inches. A bed 10 × 10 ft and 6 in deep is 10 × 10 × 0.5 = 50 ft³, not 600. Divide inches by 12 before multiplying, or use the cubic yard calculator, which takes depth in inches.
• Rounding too early. Keep two or three decimals until the end, then round up once. 4 bags of 0.6 ft³ is 2.4 ft³, or 0.089 yd³, not 0.1.
• Ignoring settling and waste. Mulch and soil compact after spreading, and concrete orders usually include a margin for spillage and an uneven base (this site’s concrete calculators default to 10%; ask your supplier what they recommend). Add the allowance to the cubic yards, then round up to the supplier’s step, often ½ or ¼ yard.
• Treating bag weight as volume. An 80 lb bag of concrete is about 0.60 ft³, not 0.8 ft³. Always use the yield printed on the bag.
• Rounding bag counts down. 90 ft³ of mulch is 45 bags of 2 ft³ but 60 bags of 1.5 ft³. Always round the bag count up to a whole bag.

Cubic feet to cubic yards vs related converters: which one to use

• This converter when you already have a volume in cubic feet, such as from bag labels or a plan.
• Cubic yard calculator when you have length, width and depth instead of a volume.
• Square feet to cubic yards when you know the area and the depth in inches.
• Bags of concrete per yard when you need bag counts for a concrete order, with waste included.
• Tons to cubic yards when the supplier quotes by weight.