How much concrete does an 80-lb bag make?

An 80-lb bag of premix concrete yields approximately 0.60 cubic feet of mixed concrete. You need about 45 bags of 80-lb mix to make one cubic yard (27 cubic feet).

How much does a bag of concrete cost?

Typical retail pricing varies by brand and region, but 40-lb bags often cost less than 60-lb bags, and 80-lb bags usually provide the best cost per cubic foot. Buying by the pallet may offer discounts.

Is bagged concrete as strong as ready-mix?

Yes, when mixed properly, bagged concrete reaches the same PSI rating shown on the bag (typically 4,000 PSI for standard mix, 5,000 PSI for high-strength). The key is using the correct water-to-mix ratio.

How many bags are in a cubic yard?

About 45 bags of 80-lb mix, 60 bags of 60-lb mix, or 90 bags of 40-lb mix equal one cubic yard. At 80-lb per bag, that's 3,600 pounds to mix for a single cubic yard.

Can I mix bags in a wheelbarrow?

Yes, a standard contractor's wheelbarrow holds about 6 cubic feet, enough for two 80-lb bags. Mix with a hoe or square shovel. For more than 10 bags, rent a portable concrete mixer for much faster results.

How long does bagged concrete take to set?

Standard bags set in 20–40 minutes and can support weight in 24–48 hours. Quick-setting bags set in 10–15 minutes. Full cure takes 28 days. Keep the surface moist for best strength development.

When should I use ready-mix instead of bags?

Ready-mix is preferred for any pour over 1 cubic yard, for structural work requiring consistent quality, or when speed is essential. The break-even point is typically around 1–1.5 cubic yards where ready-mix becomes cheaper than bags.

What water-to-bag ratio should I use?

Most 80-lb bags require about 3 quarts (0.75 gallons) of water. Always check the bag label. The mix should be workable but not soupy — like thick oatmeal. Too much water weakens the concrete.

Concrete Bag Calculator

Calculate how many bags of concrete you need. Enter your project volume to get 40-lb, 60-lb, and 80-lb bag counts with cost estimates.

Volume Needed

ft³

Waste Factor

Optional: enter bag prices for cost estimates

40-lb Bag Cost

60-lb Bag Cost

80-lb Bag Cost

Adjusted volume with waste: 28.4 ft³ (1.00 yd³)

40-lb Bags

$332.50

60-lb Bags

$315.00

80-lb Bags

$312.00

Planning notes, formulas, and examples

About the Concrete Bag Calculator

For small to medium concrete projects, bagged premix concrete is often the most accessible option. Whether you're setting fence posts, pouring a small pad, or filling sonotubes, knowing exactly how many bags to buy saves trips to the hardware store and prevents both shortfalls and waste.

This calculator converts your project's concrete volume (in cubic feet or cubic yards) into the number of bags needed for three standard sizes: 40-lb, 60-lb, and 80-lb. Each size has a different yield per bag, and the calculator accounts for a user-configurable waste factor.

The tool also estimates cost based on per-bag pricing, helping you compare bag sizes and decide whether a ready-mix delivery might be more economical for your project. As a rule of thumb, if you need more than about 45 bags (roughly 1 cubic yard), ready-mix delivery is usually faster and often cheaper.

When This Page Helps

Buying the wrong number of bags wastes money and time. Too few bags mean an extra trip to the store mid-project while your mixed concrete hardens. Too many bags mean storing heavy bags that can absorb moisture and harden in the packaging. This calculator gives you exact counts with waste allowances so you buy right the first time.

How to Use the Inputs

Enter the total volume you need in cubic feet (or convert from cubic yards by multiplying by 27).
Select or note the bag size you plan to use (40-lb, 60-lb, or 80-lb).
Set a waste factor percentage (5–10% recommended).
Optionally enter the cost per bag to see total material cost.
Review the bag counts and cost comparison across all three sizes.

Formula used

Yield per bag: 40-lb = 0.30 ft³, 60-lb = 0.45 ft³, 80-lb = 0.60 ft³
Bags = Volume (ft³) × (1 + waste%) ÷ yield per bag
Round up to whole bags

Example Calculation

Result: 48 bags (80-lb)

27 cubic feet of concrete with 5% waste = 28.35 ft³. At 0.60 ft³ per 80-lb bag, you need 28.35 / 0.60 = 47.25, rounded up to 48 bags. That's about 3,840 lbs of concrete to mix. For 60-lb bags: 63 bags. For 40-lb bags: 95 bags.

Tips & Best Practices

80-lb bags are the most cost-effective per cubic foot but are heavy be careful of your back.
60-lb bags are a good compromise between yield and manageable weight.
For projects over 1 cubic yard (about 45 bags of 80-lb), consider ready-mix delivery instead.
Store bags off the ground on pallets and cover with a tarp to prevent moisture absorption.
Mix one bag at a time in a wheelbarrow or use a portable mixer for consistent results.
In hot weather, pre-wet the mixing vessel and use cool water to extend working time.
Don't add extra water beyond package directions — it weakens the concrete significantly.

Bag Sizes and Yields

The three standard bag sizes available at hardware stores are 40-lb (0.30 ft³), 60-lb (0.45 ft³), and 80-lb (0.60 ft³). Some manufacturers also offer 50-lb bags (0.375 ft³) and 90-lb bags (0.675 ft³). Always check the yield printed on the bag, as it varies slightly between manufacturers.

When to Use Bags vs. Ready-Mix

Bagged concrete is ideal for small projects: fence posts, mailbox bases, small pads under 1 cubic yard, and sonotube fills. Ready-mix delivery makes more sense for anything over 1 cubic yard. The crossover point depends on your local ready-mix delivery charges and minimum order requirements.

Mixing Tips for Best Results

Always add water gradually — you can add more, but you can't take it out. Mix for at least 3–5 minutes until uniform in color with no dry pockets. In hot weather, wet the mixing container first and use cool water. In cold weather, store bags in a heated space before mixing.

Sources & Methodology

Last updated: February 8, 2026

Frequently Asked Questions

An 80-lb bag of premix concrete yields approximately 0.60 cubic feet of mixed concrete. You need about 45 bags of 80-lb mix to make one cubic yard (27 cubic feet).