What Does “Cubic Feet Yield” Mean for a Bag of Concrete?

Concrete & Masonry · Field Reference

Cubic Ft in an 80 lb Bag of Concrete: The Full Yield, Coverage & Calculator Guide

Everything you need to know about the cubic ft in 80 lb bag of concrete — the exact yield, how it compares to other bag sizes, how to calculate how many bags your project needs, and whether it’s safe to work with.

Quick Answer

0.60 cubic feet

One 80 lb bag of concrete mix yields approximately 0.60 cubic feet of finished concrete once mixed with water — that’s about 0.022 cubic yards, 17 liters, or roughly 4.5 gallons of volume.

02 · WHAT IT IS

What Is an 80 lb Bag of Concrete, Exactly?

An 80 lb bag of concrete is a pre-blended, dry construction material made of Portland cement, sand, and coarse aggregate (gravel or crushed stone), combined in factory-controlled ratios. All you add on-site is water. Once mixed, it hardens into structural concrete with an average compressive strength of around 4,000 psi — strong enough for slabs, footings, posts, and most residential work.

The “80 lb” refers strictly to the dry pre-mix weight. Because concrete’s dry ingredients pack to roughly 133 pounds per cubic foot, dividing the bag weight by that density (80 ÷ 133) is exactly how the industry arrives at the 0.60 cubic feet yield figure.

80 lb bag ÷ 133 lb/cu ft density ≈ 0.60 cu ft of concrete
03 · WHY IT MATTERS

Why the Cubic Feet Figure Actually Matters

Getting the cubic ft in 80 lb bag of concrete right, before you ever open a bag, is what prevents the two most common and costly mistakes on a small pour:

  • Running out mid-pour. Concrete begins setting within 30–60 minutes. If you underestimate bag count, you can end up with a visible “cold joint” where an old, partially set batch meets a new one — a permanent weak point in the slab.
  • Over-ordering and wasting money. Extra bags of hardened concrete are dead weight and dead cost. Knowing the exact yield lets you buy close to the real number, plus a sensible waste margin.
  • Passing inspection. Footings, post holes, and structural pours are often specified in cubic feet or cubic yards. Using the correct yield keeps your as-built volume matching the design volume.

In short, the yield number is the bridge between a project’s design volume (length × width × depth) and the real-world shopping list (how many bags to load into the cart).

04 · TYPES & SIZES

Types of Concrete Bags and Their Cubic Feet Yield

Bagged concrete comes in several standard sizes, and each one has a different yield. Here is how the 80 lb bag stacks up against the rest of the lineup:

Concrete bag size vs. cubic feet yield (standard concrete mix)
Bag Size Yield (cu ft) Yield (cu yd) Bags per Cu Yd Typical Use
40 lb bag0.300.01190Small repairs, edging
50 lb bag (fast-set)0.3750.01472Fence posts, quick sets
60 lb bag0.450.01760DIY slabs, steps
80 lb bag0.600.02245Patios, footings, posts

Types of bagged mix, not just bag sizes

0.60 cu ft

Standard Concrete Mix

Cement + sand + gravel. General-purpose, 4,000 psi average — the classic 80 lb bag.

0.60 cu ft

High-Strength Mix

Same yield, richer cement ratio for 5,000+ psi driveways and structural footings.

Varies

Fast-Setting Mix

Usually sold in 50 lb bags; poured dry into post holes and set with water directly in place.

No coarse rock

Sand Topping / Mortar Mix

No large aggregate, so density and yield per pound differ from standard concrete mix.

05 · HOW TO

How to Calculate How Many 80 lb Bags You Need

Use this simple three-step method to convert any project’s dimensions into a real bag count.

  1. Find your volume in cubic feet. Multiply length (ft) × width (ft) × depth (ft). If depth is in inches, divide it by 12 first.
  2. Divide by the bag’s yield. For 80 lb bags, divide your total cubic feet by 0.60.
  3. Add a waste factor. Add 5–10% to cover spillage, uneven subgrade, and mixing loss, then round up to a whole bag.
Worked example: A 10 ft × 10 ft patio poured 4 inches (0.333 ft) deep = 33.3 cubic feet. 33.3 ÷ 0.60 = 55.5 bags. Add 10% waste → about 56 bags of 80 lb concrete.

Don’t want to do the math by hand? Use the live calculator below — it applies this exact formula for any bag size.

06 · INTERACTIVE TOOL

Live Bag & Volume Calculator

How many bags do I need?

Enter your pour dimensions and pick a bag size — the fill gauge and totals update instantly.

Total volume33.33 cu ft
Bags needed (exact)55.6 bags
Bags to buy (+10% waste)62 bags

Formula: (Length × Width × Depth ÷ 12) ÷ bag yield, rounded up with a 10% waste allowance.

07 · IS IT SAFE

Is It Safe to Handle an 80 lb Bag of Concrete?

Working with bagged concrete is safe for most DIYers and professionals, provided a few precautions are followed — the risks come from two sources: the material itself and the bag’s weight.

Material hazards

  • Dry mix contains crystalline silica and lime, both of which can irritate eyes, skin, and lungs if inhaled or handled without protection.
  • Wet concrete is caustic and can cause chemical burns on prolonged skin contact.

Physical hazards

  • An 80 lb bag is at the upper end of what safety guidelines recommend for single-person manual lifting — many contractors prefer 60 lb bags for exactly this reason.
  • Repetitive lifting or awkward twisting while carrying bags is a leading cause of back strain on small job sites.
Recommended PPE: Safety glasses, an N95 dust mask when pouring or mixing dry, waterproof gloves, and boots. Lift with your legs, keep the bag close to your body, and consider a hand truck for multiple bags.
08 · PROS & CONS

Advantages and Disadvantages of 80 lb Bagged Concrete

Advantages

  • Fewer bags per job — 0.60 cu ft per bag means less lifting and fewer trips than 40 lb or 60 lb bags for the same volume.
  • No batching errors. Cement, sand, and aggregate are pre-proportioned at the factory.
  • Widely available at hardware and home improvement stores in consistent, tested yields.
  • Ideal for small-to-medium pours where ordering a ready-mix truck isn’t cost-effective.

Disadvantages

  • Heavier to lift and carry than 40 lb or 60 lb bags, which increases injury risk for solo DIYers.
  • Costlier per cubic yard than ready-mix truck delivery once a project exceeds roughly half a cubic yard.
  • More packaging waste — large pours can mean dozens of empty bags to dispose of.
  • Mixing consistency depends on the person doing it; hand-mixed batches vary more than machine-batched ready-mix.
09 · COMMON USES

Common Uses for 80 lb Bags of Concrete

Because its 0.60 cubic feet yield hits a sweet spot between coverage and portability, the 80 lb bag is the go-to choice for:

  • Fence and mailbox posts — setting posts in round holes without needing a mixer truck.
  • Small patios and walkways poured 3–4 inches thick.
  • Footings and pier pads for decks, sheds, and pergolas.
  • Steps and landing pads where precise, small-batch pours are easier to control by hand.
  • Repair work — patching cracked slabs or replacing a damaged section of sidewalk.
10 · FAQ

Frequently Asked Questions

How many cubic feet are in an 80 lb bag of concrete?+
An 80 lb bag of concrete mix yields approximately 0.60 cubic feet of finished concrete once mixed with water. This is the standard figure printed on bags from major manufacturers such as Quikrete and Sakrete.
How many 80 lb bags of concrete make a cubic yard?+
Since 1 cubic yard equals 27 cubic feet and one 80 lb bag yields 0.60 cubic feet, you need about 45 bags of 80 lb concrete to make one full cubic yard.
How many 80 lb bags of concrete equal one cubic foot?+
It takes roughly 1.66 bags to fill one cubic foot, so in practice you should round up and plan for 2 bags per cubic foot to avoid running short mid-pour.
What is the difference between a 60 lb and an 80 lb bag in cubic feet?+
A 60 lb bag yields about 0.45 cubic feet while an 80 lb bag yields about 0.60 cubic feet — roughly a third more volume per bag, which is why fewer 80 lb bags are needed for the same job despite being heavier to carry.
How much water do I need for an 80 lb bag of concrete?+
Most 80 lb bags need approximately 6 pints (about 3 quarts) of clean water to start, with more added gradually until the mix reaches a stiff, workable consistency with no standing puddles.
How much area does an 80 lb bag of concrete cover?+
At a standard 2 inch depth, one 80 lb bag covers about 3.6 square feet. At a 4 inch slab depth, common for walkways and patios, the same bag covers roughly 1.8 square feet.
Is it safe to work with 80 lb bags of concrete?+
Yes, when handled correctly. Dry mix contains crystalline silica and lime, so wear gloves, safety glasses, and a dust mask when pouring or mixing, and use proper lifting technique because of the bag’s weight.
How long does an 80 lb bag of concrete take to cure?+
Concrete from an 80 lb bag typically sets enough to finish within 30 to 60 minutes, can usually be walked on after 24 to 48 hours, and reaches full designed strength after about 28 days of curing.
Do all brands of 80 lb concrete bags yield the same cubic feet?+
Most major brands, including Quikrete and Sakrete, list the same approximate 0.60 cubic foot yield for standard 80 lb concrete mix, since the figure comes from the density of the aggregate blend rather than the brand name. Always check the yield printed on your specific bag.
How many 80 lb bags do I need for a 10×10 patio?+
A 10 ft by 10 ft patio poured 4 inches thick requires about 33.3 cubic feet of concrete, which works out to roughly 56 bags of 80 lb concrete once a 10 percent waste allowance is included.