How many 80 lb bags are in a cubic yard?

An 80 lb bag of concrete mix yields about 0.6 cubic feet, so a cubic yard (27 cubic feet) takes roughly 45 bags.

Should I order a little extra?

Yes. Most pros add 5–10% to cover spillage, uneven ground and over-excavation.

Concrete Calculator

Calculate cubic yards, cubic feet and bags needed for any pour.

100% free to useNo sign-up requiredImperial & metric units

How much concrete do I need?

To find how much concrete you need, multiply length by width by depth in feet, then divide by 27 to get cubic yards. A 10 ft by 10 ft slab at 4 inches thick needs 1.24 cubic yards, or about 56 of the 80 lb bags. Add 5 to 10 percent for waste before ordering.

Inputs

Pour shape

Switch shapes to size walls, footings, tube forms or pads.

Lengthft

Widthft

Depth / thicknessin

How many identical pourscount

Waste allowanceApplied to material quantities

Results

Cubic Yards

4.94 yd³

Order this from ready-mix

Cubic Feet

133.3 ft³

80 lb Bags

223

If mixing on site

60 lb Bags

297

Estimates update instantly as you type. Confirm against local code before ordering materials.

Concrete is sold by the cubic yard, but almost every measurement on a jobsite is taken in feet and inches. That mismatch is where ordering mistakes happen. This calculator converts your slab, footing, or column dimensions into the exact cubic yardage you need, then translates that volume into 60 lb and 80 lb bag counts so you can decide between ready-mix delivery and mixing on site.

Whether you are pouring a garage pad, a set of footings, a patio, or a sidewalk, the math is the same: length times width times depth, divided by 27 to convert cubic feet into cubic yards. The hard part is keeping units consistent and remembering to add a waste allowance for spillage, over-excavation, and uneven subgrade. The waste control built into this tool handles that for you in one tap.

How concrete volume is calculated

Concrete volume is the product of the three dimensions of the pour, converted from feet to cubic yards since concrete is ordered by the yard. Bag counts come from dividing total cubic feet by the yield of a single bag.

Cubic Yards = (Length ft × Width ft × Depth ft) ÷ 27

Concrete bag yield reference

How many bags of concrete mix make up one cubic yard.

Bag size	Yield per bag	Bags per cubic yard	Bags per cubic foot
40 lb	0.30 ft³	90 bags	3.3 bags
60 lb	0.45 ft³	60 bags	2.2 bags
80 lb	0.60 ft³	45 bags	1.7 bags

One cubic yard equals 27 cubic feet. Mixing more than 20 to 25 bags by hand is rarely worth it versus ready-mix delivery.

How to use it

1Enter the length and width of the area in feet.
2Enter the depth or thickness of the slab in inches.
3Read the cubic yards, cubic feet and bag estimate instantly.
4Add a waste factor of 5–10% before ordering.

Key terms explained

Cubic yard: The standard unit ready-mix concrete is ordered and priced in. One cubic yard equals 27 cubic feet and fills a 3 ft by 3 ft by 3 ft cube.
Subgrade: The compacted soil or gravel base beneath a pour. Soft or uneven subgrade increases the concrete needed and is a common source of overruns.
Yield: How much volume one bag of mix produces. An 80 lb bag yields about 0.60 cubic feet; a 60 lb bag yields about 0.45 cubic feet.
Slump: A measure of how wet and workable a mix is. It does not change volume but affects placement and finishing.

Worked examples

Garage slab

A 20 ft × 20 ft garage poured 4 in thick needs about 4.94 cubic yards of concrete.

Sidewalk

A 40 ft × 3 ft walkway at 4 in deep works out to roughly 1.48 cubic yards.

Pro tips from the field

1Order full yards when you are close to a half-yard threshold; suppliers charge short-load fees for partial loads.
2For footings and trenches, measure depth at several points; over-dig averages 10 to 15 percent more volume than the plan.
3Mixing more than 20 to 25 bags by hand is rarely worth it, time and consistency favor ready-mix at that point.
4Keep your finishing crew sized to the pour, large slabs set up faster than two people can finish in summer heat.

Common mistakes

Entering depth in feet instead of inches.
Forgetting to add a waste allowance for spillage and uneven subgrade.
Mixing bag yields — 60 lb and 80 lb bags cover different volumes.

Where it gets used

Garage and shed pads

Size a 4 inch pad with a thickened edge in a single estimate before booking the truck.

Footings and piers

Total multiple footing pours quickly so you order one combined load instead of several.

Patios and walkways

Price homeowner hardscape jobs with confidence and avoid a second, expensive partial delivery.

Frequently asked questions

Free Concrete Calculator for Slabs and Pours

The FoxCalc concrete calculator gives contractors and homeowners a fast, accurate estimate of how much concrete a project requires. Enter your dimensions and instantly see the volume in cubic yards and cubic feet along with the number of pre-mixed bags needed.

Whether you are pouring a driveway, footing, slab or sidewalk, accurate volume estimates prevent costly mid-pour shortages and wasted material. Always confirm depth requirements with your local building code before ordering.