How Many Cubic Feet in an 80lb Bag of Quikrete? Complete Guide

If you’re planning a concrete project, one of the first questions you’ll ask is: how many cubic feet in an 80lb bag of Quikrete?

Here’s the quick answer:

👉 An 80lb bag of Quikrete yields approximately 0.60 cubic feet of concrete.

That means each bag fills just over half a cubic foot when mixed properly.

But to avoid running out of concrete—or wasting money—you need to understand how this number works in real projects. This guide will walk you through calculations, coverage charts, and expert tips to get it right the first time.

Quick Answer: How Many Cubic Feet in an 80lb Bag of Quikrete?

Let’s break it down clearly:

1 bag (80 lb) = 0.60 cubic feet
2 bags = 1.2 cubic feet
10 bags = 6 cubic feet

👉 So, if your project requires 6 cubic feet of concrete, you’ll need about 10 bags.

Understanding Concrete Volume and Yield

Before calculating anything, you need to understand what “cubic feet” means.

What Is a Cubic Foot?

A cubic foot is a volume measurement:

1 ft × 1 ft × 1 ft = 1 cubic foot

It tells you how much space something fills.

Why Yield Matters

Concrete bags don’t just represent weight—they represent volume after mixing.

Yield helps you:

Estimate how many bags to buy
Avoid shortages
Control costs

Quikrete 80lb Bag Yield Explained

An 80lb bag of Quikrete typically produces:

👉 0.60 cubic feet of finished concrete

Why Not 1 Cubic Foot?

Because:

The dry mix contains air gaps
Water activates and compacts the mix
The final volume is smaller than the dry ingredients

Key Fact:

👉 1 cubic yard = 27 cubic feet

This becomes important for larger projects.

Coverage Chart for 80lb Bag of Quikrete

Here’s how much area one bag can cover depending on thickness:

Thickness	Coverage per 80lb Bag
2 inches	3.6 sq ft
3 inches	2.4 sq ft
4 inches	1.8 sq ft
6 inches	1.2 sq ft

👉 Thicker slabs require more concrete.

How to Calculate Concrete Needed (Step-by-Step)

Follow this simple method:

Step 1: Measure Area

Length × Width

Example:

10 ft × 10 ft = 100 sq ft

Step 2: Convert Thickness to Feet

4 inches ÷ 12 = 0.33 ft

Step 3: Calculate Volume

Volume = Area × Thickness

100 × 0.33 = 33 cubic feet

Step 4: Divide by Bag Yield

33 ÷ 0.60 = 55 bags

👉 You’ll need about 55 bags of 80lb Quikrete

How Many 80lb Bags Make a Cubic Yard?

Let’s convert cubic feet to cubic yards.

Formula:

1 cubic yard = 27 cubic feet

Now divide:

👉 27 ÷ 0.60 = 45 bags

Final Answer:

👉 45 bags of 80lb Quikrete = 1 cubic yard

Quick Reference:

Cubic Yards	Bags Needed
1 yard	45 bags
2 yards	90 bags
3 yards	135 bags

Real-Life Project Examples

1. Fence Post Installation

Hole size:

1 ft diameter
2 ft deep

Volume:
👉 ~1.57 cubic feet

Bags needed:
👉 1.57 ÷ 0.60 ≈ 3 bags per post

2. Small Patio Slab

Size:

8 ft × 10 ft
4 inches thick

Volume:
👉 26.4 cubic feet

Bags:
👉 44 bags

3. Deck Footings

Each footing:

1 cubic foot

👉 Requires about 2 bags per footing

Factors That Affect Concrete Yield

The 0.60 cubic feet is an estimate. Actual yield can vary.

1. Water Ratio

Too much water:

Weakens concrete
Slightly increases volume

Too little:

Hard to mix
Reduces workability

2. Mixing Method

Hand mixing may be uneven
Machine mixing is more consistent

3. Compaction

Air pockets reduce strength and volume accuracy.

4. Waste and Spillage

Always add 5–10% extra for safety.

Common Mistakes to Avoid

1. Not Calculating Volume Properly

Skipping thickness conversion leads to wrong estimates.

2. Buying Exact Amount Only

Always buy extra bags.

3. Ignoring Depth Variations

Uneven ground changes required volume.

4. Using Wrong Bag Size

Not all bags yield the same volume.

Expert Tips for Using Quikrete

Want professional-level results? Follow these tips:

Always measure twice before buying
Add water gradually while mixing
Use a wheelbarrow or mixer for consistency
Compact concrete to remove air bubbles
Finish surface quickly before it sets

Comparison: 60lb vs 80lb vs 90lb Bags

Bag Size	Yield (Cubic Feet)
60 lb	0.45
80 lb	0.60
90 lb	0.67

👉 Larger bags reduce the number of bags needed.

Practical Use Cases

When to Use 80lb Bags:

Medium projects
Fence posts
Small slabs

When to Avoid:

Large driveways
Big foundations (use ready-mix instead)

FAQs

1. How many cubic feet in an 80lb bag of Quikrete exactly?

An 80lb bag yields approximately 0.60 cubic feet of concrete.

2. How many bags do I need for 1 cubic yard?

You need about 45 bags of 80lb Quikrete.

3. How much area does one bag cover?

It covers about 1.8 sq ft at 4 inches thick.

4. Should I buy extra concrete bags?

Yes, always add 5–10% extra to avoid shortages.

5. Can yield vary from 0.60 cubic feet?

Yes, depending on water, mixing, and compaction.

Conclusion

So, let’s answer it clearly:

👉 How many cubic feet in an 80lb bag of Quikrete?
It yields approximately 0.60 cubic feet.

This simple number is essential for planning any concrete project. Whether you’re setting fence posts, pouring a slab, or building a patio, knowing the yield helps you estimate accurately and avoid costly mistakes.

Remember:

1 bag = 0.60 cubic feet
45 bags = 1 cubic yard
Always calculate volume before buying

With this knowledge, you can confidently plan your next project and get professional-quality results.