# Concrete Slab Cost Calculator: Yards, Bags, and Price

Canonical URL: https://www.simplywise.com/blog/concrete-slab-cost-calculator/
Plain text: https://www.simplywise.com/blog/concrete-slab-cost-calculator/llms.txt
Publisher: SimplyWise, Inc. (https://www.simplywise.com)
Published: September 7, 2026
Updated: October 5, 2026
Category: How to Estimate
Summary: Concrete slab cost calculator: the cost of a 30x30 concrete slab or any size, yards to order, bag counts, and a sourced price per yard, live on the page.

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## Concrete Slab Cost Calculator: Cost to Pour, Yards, Bags

Concrete is sold by the cubic yard, so concrete slab cost is a volume question. Set the slab below; yards, bags, and dollars update as you type.

Size the pour, see the price

Length (ft)

Width (ft)

Thickness

Custom

Extra for waste (%) NRMCA CIP 31: order 4% to 10% over plan

Local quote ($/cu yd)

2.00 cubic yards to order

Slab volume1.78 cu yd

Bags instead88 bags of 80 lb mix

Material cost$320 to $360

Published range, updated Aug 27, 2026, from published averages of $160 to $180 per cubic yard. Local prices vary.

At a glance

1. Length times width times thickness in feet, divided by 27, gives cubic yards.
2. Order 4% to 10% over plan, per NRMCA CIP 31. The default here is 10%.
3. Ready mix averaged $160 per cubic yard in 2023 per NRMCA. A large-producer index puts 2025 near $180.
4. An 80 lb bag yields 0.60 cu ft, so a full cubic yard is 45 bags.
5. A 12 by 12 slab at 4 in is 2 yards ordered, $320 to $360 in concrete.
6. The range is national. Two local plant quotes settle the real price.

## How the concrete slab cost calculator works

The cost of a concrete slab is three moves. Multiply length by width by thickness in feet for cubic feet. Divide by 27 for cubic yards. Multiply by the price per yard. That is the cost to pour a concrete slab at any size.

Thickness trips people because it is in inches. Divide by 12 first. A 4 in slab is 0.333 ft, so each square foot of slab is a third of a cubic foot.

The calculator adds waste and rounds up to the next quarter yard. NRMCA CIP 31 says to order 4% to 10% over the plan quantity for spillage, uneven subgrade, and over-excavation. Coming up short means a second delivery and a cold joint.

## Worked example: a 12×12 patio at 4 inches

Area is 144 sq ft. At 0.333 ft thick that is 48 cu ft, or 1.78 cubic yards. Add 10% waste for 1.96, round up, and order 2 cubic yards.

At the published national averages of $160 to $180 per cubic yard, the concrete runs $320 to $360. That is material only; base, forms, reinforcement, labor, and finishing are separate lines.

## Concrete slab cost by size, 10×10 to 30×30

All rows: 4 inches thick, 10% waste, rounded up to the quarter yard, national material range.

| Slab | Volume | Order | 80 lb bags | Material cost |
| --- | --- | --- | --- | --- |
| 10×10 | 1.23 cu yd | 1.50 cu yd | 62 | $240 to $270 |
| 12×12 | 1.78 cu yd | 2.00 cu yd | 88 | $320 to $360 |
| 16×20 | 3.95 cu yd | 4.50 cu yd | 196 | $720 to $810 |
| 20×20 | 4.94 cu yd | 5.50 cu yd | 245 | $880 to $990 |
| 24×24 | 7.11 cu yd | 8.00 cu yd | 352 | $1,280 to $1,440 |
| 30×30 | 11.11 cu yd | 12.25 cu yd | 550 | $1,960 to $2,205 |

At 6 in, common for garages, every number rises by half again. The 24×24 order becomes 11.75 yards, not 8.

## What drives the cost per square foot and per yard

NRMCA put the average 2023 selling price at $160 per cubic yard, on 400 million cubic yards delivered. Producers in its benchmarking survey ranged from about $150 to $171 per yard, so identical mixes price differently plant to plant.

Prices have climbed. An index of four large public producers rose from $113 per yard in 2016 to $180 in 2025, skewing commercial. Those two anchors, $160 and $180, are the range this page uses.

What moves a local quote: mix strength, distance, and load size. Mixers carry 8 to 12 cubic yards per CIP 31, and it warns against ordering small cleanup loads. Quote the yard locally; the volume math holds.

## Turn the yards into a quote

The calculator prices the concrete; the job has six more lines. SimplyWise Cost Estimator turns a photo into an itemized estimate in about 6 seconds. Pricing is $29.99/mo or $239.99/yr, about $20/mo on annual, with a 7-day free trial.

## Bags or a truck

QUIKRETE and Sakrete both publish an 80 lb bag at 0.60 cu ft, so a cubic yard is 45 bags; a 60 lb bag at 0.45 cu ft is 60. The 12 by 12 patio is 88 bags with waste, 7,040 lb through a mixer one bag at a time.

Bags win small work: post runs, a condenser pad, repairs. Past a yard, the truck wins on your back.

## Run the estimate in this order

1. Measure the pour, not the patio Length, width, thickness. Thickness moves the total fastest, so confirm it against the plan first.
2. Add waste before you order CIP 31 calls for 4% to 10% over plan. Uneven subgrade eats concrete you cannot see.
3. Get two plant quotes per yard The national range brackets the market. A local quote typed into the calculator reprices the order exactly.
4. Put the whole job on paper Concrete is one line. Base, forms, steel, labor, and finish are the rest of the estimate the customer signs.

## Keep reading

- Drywall Calculator: Sheets and Mud (https://www.simplywise.com/blog/drywall-sheet-and-mud-calculator/)
- Fence Cost Calculator (https://www.simplywise.com/blog/fence-cost-calculator/)
- Hardscape Pricing Guide (https://www.simplywise.com/blog/hardscape-pricing-guide/)
- Concrete Driveway Cost (https://www.simplywise.com/blog/concrete-driveway-cost/)
- Concrete Cubic Yard Calculator (https://www.simplywise.com/blog/concrete-cubic-yard-calculators/)
- Project Cost Guides (https://www.simplywise.com/blog/cost-guides/)
- Construction Calculators for Contractors (https://www.simplywise.com/blog/construction-calculators/)

## Sources

- NRMCA CIP 31, Ordering Ready Mixed Concrete (https://www.nrmca.org/wp-content/uploads/2021/01/31pr.pdf) (4% to 10% over plan; trucks 8 to 12 cu yd; verified 2026-08-27).
- NRMCA, Performance Benchmarking Survey and State of the Industry (https://www.nrmca.org/wp-content/uploads/Performance_Benchmarking_Survey_and_State_of_the_Industry.pdf) (2023 average $160 per cu yd; quartiles $150.03 to $170.66; verified 2026-08-27).
- Concrete Financial Insights, US Concrete Industry Data (https://concretefinancialinsights.com/us-concrete-industry-data) (large-producer index $113.08 in 2016 to $179.95 in 2025; verified 2026-08-27).
- QUIKRETE Concrete Mix, data sheet No. 1101 (https://www.quikrete.com/pdfs/data_sheet-concrete%20mix%201101.pdf) (80 lb yields 0.60 cu ft; 60 lb 0.45; verified 2026-08-27).
- Sakrete, High-Strength Concrete Mix (https://www.sakrete.com/product/high-strength-concrete-mix/) (same published yields: 80 lb 0.6 cu ft, 60 lb 0.45; verified 2026-08-27).
- SimplyWise Cost Estimator, App Store (https://apps.apple.com/us/app/simplywise-cost-estimator/id6670619664) (4.8 rating; verified 2026-08-22).

## Common questions on slab pricing

**How much does a 12×12 concrete slab cost?**

Order 2 cubic yards at 4 in thick with 10% waste. National averages of $160 to $180 per cubic yard put the concrete at $320 to $360, before base and labor.

**How many yards of concrete for a 24×24 slab?**

At 4 in thick the slab holds 7.11 cubic yards. With 10% waste you order 8. At 6 in, common for garages, the order is 11.75.

**Cost of a 30×30 concrete slab, 4 inches thick?**

At 4 in thick the order is 12.25 cubic yards, or $1,960 to $2,205 in concrete at the national averages. Mixers carry 8 to 12 yards, so plan two trucks.

**How many 80 lb bags of concrete make a cubic yard?**

45. QUIKRETE and Sakrete both list an 80 lb bag at 0.60 cu ft, and 27 divided by 0.60 is 45. A 60 lb bag runs 60 to the yard.

**Does the calculator include labor or base prep?**

No. It prices the concrete from published national averages. Excavation, base, forms, reinforcement, labor, and finishing are local lines on the full estimate.

**Can SimplyWise price a concrete slab from a photo?**

Yes. SimplyWise Cost Estimator turns a photo into an itemized estimate in about 6 seconds. Free to try, at $29.99/mo or $239.99/yr.

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## About SimplyWise

SimplyWise, Inc. (New York, NY) builds mobile apps for contractors, tradespeople, and small business owners. The SimplyWise Cost Estimator turns a job site photo into an itemized estimate with labor and material costs in about 6 seconds, and the client signs the branded quote to approve it. It is rated 4.8 on the App Store. It is free to try with a 7-day free trial, then $29.99 per month or $239.99 per year (about $20 per month on the annual plan), and one subscription includes every app in the SimplyWise suite.

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