Concrete Bags Calculator
How many bags of concrete do I need? Get bag count for 40, 60, and 80 lb bags, bags per cubic yard, weight, and cost for slabs, footings, and posts.
Project Dimensions
Project preset
Concrete Slab
4" typical
Patio or shed base. 80lb bags keep the bag count lower.
Ready to calculate
Enter your project dimensions
Last updated June 23, 2026 by our expert review team
Bag Coverage Guide
40 lb
Easier to carry
Yield: 0.3 cu ft
At 4": 0.9 sq ft
Price: $4.5
50 lb
Middle weight
Yield: 0.375 cu ft
At 4": 1.1 sq ft
Price: $5
60 lb
Most common
Yield: 0.45 cu ft
At 4": 1.4 sq ft
Price: $5.5
80 lb
Best value
Yield: 0.6 cu ft
At 4": 1.8 sq ft
Price: $6.5
Expert Contributors
Ehsan Ghazanfari
Licensed Structural Engineer
FISE-certified structural engineer with 11+ years designing bridges, retaining walls, and foundations. MSc from Aalto University.
See full profileCherry Jane Limbago
Licensed Civil Engineer & Master Plumber
Licensed civil engineer and master plumber with 10+ years in structural design, estimation, and project management. Currently Project Engineer at Universal Robina Corporation.
See full profileUpdated June 2026
How we verify our calculatorsBag Count Decision Guide
Bagged concrete is practical for small pours. Once a project approaches one cubic yard, compare the bag count, lifting weight, and mixing time against a ready-mix quote.
How Many Bags of Concrete in a Cubic Yard?
It takes about 45 × 80 lb bags to make one cubic yard of concrete. Smaller bags mean more bags — and more mixing. Use this to sanity-check a bag order against a ready-mix quote.
| Bag size | Yield per bag | Bags per cubic yard | Bags per ½ yard |
|---|---|---|---|
| 80 lb | 0.6 cu ft | 45 | 23 |
| 60 lb | 0.45 cu ft | 60 | 30 |
| 50 lb | 0.375 cu ft | 72 | 36 |
| 40 lb | 0.3 cu ft | 90 | 45 |
Based on standard concrete mix yields (Quikrete/Sakrete). High-early-strength and lightweight mixes vary — check the bag. Past ~1 cubic yard, ready-mix usually wins on cost and effort.
Bags or Ready-Mix? Cost & Effort
Bags win small jobs; ready-mix wins on cost and effort past a point. Find your crossover.
Small-order surcharge ready-mix adds under ~4 yd.
Bagged
$163
25 × 80 lb bags
2,000 lb to haul & mix
Ready-mix
$203
0.50 yd delivered
incl. $120 short-load fee
At 0.50 yd, bagged is cheaper ($40 less). Ready-mix overtakes bags above ~0.77 yd.
Estimates: bagged includes 10% waste at $6.5/bag; confirm ready-mix minimums and fees locally.
How Many Bags for a Concrete Slab?
Assumes a 4" slab, 80 lb standard concrete mix, and 10% extra for waste and uneven subgrade.
Bags vs Ready-Mix
Bags are easiest
Use a mixer
Quote ready-mix
One cubic yard is about 45 bags of 80 lb mix, before extra material. That is the practical hand-mixing threshold for most DIY jobs.
Pro Tips
Mix only what you can place and finish in one run. Cold joints happen when one batch stiffens before the next is ready.
Add water slowly. QUIKRETE lists about 6 pt of starting water for an 80 lb bag, then more only as needed for a stiff, moldable mix.
Dampen the base before pouring, but do not leave puddles. Dry soil steals water from the bottom of the slab.
Use forms, even for small pads. Concrete spreads thin at unsupported edges and changes your bag count fast.
Cut control joints while the concrete is still workable. Planned joints are cheaper than random cracks.
For steps, use the concrete steps calculator. For round post holes, use the concrete cylinder calculator.
If excavation comes first, estimate removed soil with the excavation calculator.
Sakrete & Quikrete Bag Coverage
Most standard Sakrete and Quikrete concrete mixes use the same planning yields by bag weight. Always check the bag label for fast-setting, high-strength, or lightweight mixes.
| Bag type | Typical yield | 4 in slab coverage | Best use |
|---|---|---|---|
| Sakrete or Quikrete 80 lb | 0.60 cu ft | about 1.8 sq ft | Small slabs, pads, and post work |
| Sakrete or Quikrete 60 lb | 0.45 cu ft | about 1.35 sq ft | Easier lifting, more bags |
| Sakrete or Quikrete 40 lb | 0.30 cu ft | about 0.9 sq ft | Repairs and patch pours |
How the Calculator Works
Enter the project footprint and depth. The calculator converts the pour to cubic feet, adds waste, then divides by the yield of the bag size you selected.
- Depth drives the order. A 6" slab uses 50% more concrete than a 4" slab with the same footprint.
- Waste is practical, not padding. Forms leak, subgrades vary, and wheelbarrows leave a little behind.
- Bag yield is the source of truth. Standard 80 lb bags yield about 0.60 cu ft; specialty mixes can differ.
Formula
Volume (cu ft) = Length × Width × (Depth ÷ 12)
Bags Needed = Volume ÷ Bag Yield × (1 + Waste %)
Quick Reference
- 80lb bag yield
- 0.60 cu ft
- 60lb bag yield
- 0.45 cu ft
- 50lb bag yield
- 0.375 cu ft
- 40lb bag yield
- 0.30 cu ft
- Cure time (min)
- 24-48 hours
- Full strength
- 28 days
Common Questions
How many bags of concrete do I need?
Multiply length x width x depth for cubic feet, add waste, then divide by the yield printed on the bag.
How many 80 lb bags are in a cubic yard?
About 45 bags, before waste. With a 10% buffer, plan closer to 50 bags per cubic yard.
What does an 80 lb bag cover?
One 80 lb bag yields about 0.60 cu ft. At 4 inches thick, that covers about 1.8 sq ft.
How many 60 lb bags are in a cubic yard?
About 60 bags, before extra material. A 60 lb bag yields about 0.45 cu ft.
When should I order ready-mix?
Once the calculator is near 1 cubic yard, get a ready-mix quote. Mixing 45+ heavy bags is slow and tiring.
How much waste should I add?
Use 5% for tight forms on compacted base, 10% for most DIY pours, and 15-20% for uneven ground.
How thick should concrete be?
Use 4" for patios and walks, 6" for light driveways, and 8-12" for many footings. Structural work should follow local code.
Can I use this for post holes?
For square holes, yes. For round holes or sonotubes, use the concrete cylinder calculator.
Do bag yields vary by product?
Yes. Standard mixes are usually 0.30, 0.45, and 0.60 cu ft for 40, 60, and 80 lb bags. Lightweight/high-yield mixes can be different.
Concrete Bag Mistakes That Cost You Money
Adding too much water
If you can pour it like a milkshake, add dry mix. Proper concrete holds its shape when cut with a trowel.
Skipping the subgrade prep
Remove all organic material, compact the soil, and add 2 to 4 inches of compacted gravel for slabs 4" or thicker.
Pouring in the wrong weather
Below 50°F slows curing dangerously; above 90°F causes flash-set cracking. Aim for 50 to 80°F with overcast skies.
Not using forms or edge support
Without forms, edges spread thin. Stake 2×4 forms every 2 to 3 feet and brace corners firmly.
Mixing too many bags at once
Concrete sets in 30 to 45 minutes. Mix 2 to 3 bags at a time and keep a steady pace.
Forgetting control joints
Cut joints every 8 to 10 feet so cracks follow planned lines instead of wandering randomly.
Concrete Bag Estimates for Common Projects
10 x 10 Patio Slab
4" thickIncludes 10% extra. This is already past the comfort zone for hand mixing, so compare against a small ready-mix delivery.
6 Fence Post Holes
10" wide x 24" deepTypical round-hole math. Use the cylinder calculator for exact post diameter, hole diameter, and depth.
4 x 20 Sidewalk
4" thickRight at the bags-vs-truck threshold. If the short-load fee is reasonable, ready-mix saves a long mixing session.
Important Disclaimer
These estimates are for planning purposes only. Actual costs vary by location, material availability, and project complexity. Always get at least 3 local quotes. This calculator does not replace professional advice.