Concrete Calculator 2026 - Cubic Yards, Bags & Cost Estimator
Calculate concrete for any project - slabs, footings, columns, walls, and stairs. Get instant cubic yard volume, exact bag counts, rebar estimates, and a full cost breakdown updated for 2026 USA prices. Works for DIY and professional contractors.
Key Concrete Facts for 2026
Concrete Weight
Per cubic foot (4,050 lbs/cu yd)
Ready-Mix Cost
Per cubic yard (2026 USA average)
Standard Slab Depth
Residential slabs and patios
Full Cure Time
100% design strength achieved
Who Uses This Concrete Calculator?
DIY Homeowners
Plan a concrete patio, backyard slab, or walkway without overspending on material. Get exact bag counts before heading to the hardware store.
Concrete Contractors
Generate fast, accurate material estimates for bids. Calculate cubic yards, rebar, and cost for driveways, foundations, and slabs in seconds.
Structural Engineers
Quickly verify volume calculations for footings, columns, and walls. Cross-check material quantities against spec sheets and design plans.
Landscapers
Estimate concrete for retaining walls, garden edging, steps, and decorative features. Calculate odd shapes including circles and trapezoids with ease.
🧮 Concrete Calculator
How the Concrete Calculator Works
Select Your Project Shape
Choose from rectangle, circle, triangle, column, stairs, or curb and gutter. Each shape uses the correct volume formula for accurate results.
Enter Dimensions
Input your measurements in feet and inches. The calculator automatically converts everything to cubic yards - the standard unit for ordering concrete in the USA.
Set Your Options
Choose PSI strength, bag size, waste factor, and whether you need rebar, gravel base, and labor cost estimates. Defaults follow ACI construction standards.
Get Instant Results
Receive cubic yards, bag count, rebar quantity, gravel volume, and full cost breakdown. Download a professional PDF report for your project records.
How to Calculate Concrete for Any Project
Calculating concrete starts with volume. Multiply length x width x depth (all in feet) to get cubic feet, then divide by 27 to convert to cubic yards. For example, a 10 x 20 slab at 4 inches (0.333 ft) deep equals 66.67 cubic feet, or 2.47 cubic yards. Always add a 10% waste factor, giving you 2.72 cubic yards to order. Our full guide on how to calculate concrete walks through each step in detail.
Circles use the formula: pi x radius squared x depth. A 12-foot diameter circle pad at 4 inches deep requires about 1.40 cubic yards before waste. Columns use the same formula with height instead of depth. For complex projects like stairs, each step is calculated as rise x run x width, then multiplied by the number of steps. The concrete formula calculation guide covers all shapes with worked examples.
Choosing the Right PSI Strength
PSI determines how strong your concrete is after curing. For most residential projects, 3,000 PSI handles patios, sidewalks, and light slabs. Driveways require at least 4,000 PSI to handle vehicle weight and freeze-thaw cycles. Use our concrete slab calculator for a dedicated slab estimator with PSI-based mix recommendations.
| PSI Rating | Best For | Typical Use | Cost Premium |
|---|---|---|---|
| 2,500 PSI | Sidewalks, paths | Light foot traffic only | Base price |
| 3,000 PSI | Patios, floors, walls | Standard residential | +$5/cu yd |
| 3,500 PSI | Pool decks, heavy slabs | Heavier residential | +$10/cu yd |
| 4,000 PSI | Driveways, garages | Vehicle traffic | +$15/cu yd |
| 4,500-5,000 PSI | Commercial, structural | Heavy loads, industrial | +$20-30/cu yd |
How Much Concrete Do I Need? (Quick Reference)
A standard 4-inch slab requires about 1.23 cubic yards per 100 square feet of area. A 20 x 20 garage slab needs roughly 5 cubic yards. For footings and foundations, depth increases dramatically - a 12-inch footing uses 3x the concrete of a 4-inch slab for the same footprint. Always check local building codes for minimum depth requirements based on your frost line. See our guide on how to measure concrete properly for professional tips.
Ready-Mix vs. Bagged Concrete
Ready-mix is cost-effective for projects over 1 cubic yard (about 45 bags at 80 lbs each). For a 10 x 10 slab at 4 inches, you need 1.23 cubic yards - that's 56 bags of 80 lb concrete or a small ready-mix order. Ready-mix runs $125-$175 per cubic yard delivered in 2026. Bagged concrete costs $6-$8 per 80 lb bag at retail, making it roughly $270-$360 per cubic yard - more than double the ready-mix price. Use our concrete bag calculator to see the exact bag count and compare costs.
💡 Pro Tip: Order 10% Extra
Always add at least 10% to your calculated volume. Subgrades are never perfectly level, forms bow slightly under pressure, and some concrete is lost during placement. Unused ready-mix is charged by the yard, so rounding up beats running short mid-pour.
⚠️ Safety First
Fresh concrete is highly alkaline and can cause chemical burns on contact with skin. Always wear gloves, safety glasses, and rubber boots when working with concrete. Avoid breathing concrete dust - use an N95 mask when mixing dry bags.
Real Construction Project Examples
🏠 20 x 20 Garage Slab
Dimensions: 20 ft x 20 ft x 6 in.
PSI: 4,000 (vehicles)
Rebar: #4 on 18 in. centers
Waste: 10%
📦 5.49 cubic yards of concrete
🔩 318 linear ft of rebar
💰 $2,300-$2,900 total estimated cost
At 6 inches thick for vehicle weight, this garage slab needs nearly double the concrete of a 4-inch patio. Use our slab calculator for detailed breakdowns.
🚗 Residential Driveway
Dimensions: 12 ft x 40 ft x 4 in.
PSI: 4,000
Rebar: #4 on 18 in. centers
Gravel base: 4 in.
📦 5.93 cubic yards with waste
🪨 1.97 cubic yards gravel base
💰 $3,100-$4,200 total estimated cost
A 12 x 40 ft driveway is one of the most common residential projects. See the full breakdown with our concrete driveway calculator.
🏛️ 8 Deck Footings
Diameter: 12 in. (1 ft)
Depth: 48 in. (4 ft)
Quantity: 8 columns
PSI: 3,500
📦 1.03 cubic yards total
🛍️ 47 bags of 80 lb concrete
💰 $290-$380 materials only
8 small footings add up to just over 1 yard - a perfect bagged concrete project. Use our column calculator for deck and pier footing estimates.
Concrete Calculator - Frequently Asked Questions
How many cubic yards of concrete do I need for a 10x10 slab?
A 10 x 10 slab at 4 inches thick needs 1.23 cubic yards before waste, or 1.35 cubic yards with a 10% waste factor. At 6 inches thick, that becomes 1.85 cubic yards with waste. Our concrete calculator above gives you the exact amount for any dimensions.
How do I convert cubic feet to cubic yards?
Divide cubic feet by 27. There are 27 cubic feet in one cubic yard (3 ft x 3 ft x 3 ft = 27 cu ft). For example, 67 cubic feet / 27 = 2.48 cubic yards. This calculator handles all conversions automatically. See our detailed concrete yardage calculator for more conversion options.
How many bags of concrete make a cubic yard?
One cubic yard requires approximately 45 bags of 80 lb concrete, 60 bags of 60 lb concrete, or 90 bags of 40 lb concrete. For large projects over 1 cubic yard, ready-mix delivery is almost always cheaper than bags. Our concrete bag calculator shows an exact count with cost comparison.
What is the standard concrete slab thickness?
Standard residential slabs are 4 inches thick. Driveways need 4-6 inches depending on vehicle weight. Garage floors should be 5-6 inches. Pool decks and patios use 4 inches. Structural footings range from 8 to 12 inches based on load and local frost depth requirements per IBC 2024.
How much does it cost to pour a concrete slab in 2026?
Concrete slab costs range from $4 to $8 per square foot for a basic 4-inch slab in 2026, including materials and labor. A 12 x 12 patio costs $580-$1,150. A 20 x 20 garage slab runs $1,600-$3,200. Use our concrete cost calculator for a detailed cost breakdown by region.
Do I need rebar in a concrete slab?
Most residential slabs benefit from reinforcement. Thin 4-inch slabs for patios and walkways can use wire mesh or #3 rebar on 18-inch centers. Driveways and garage floors need #4 rebar on 12-18 inch centers. Any slab subject to vehicle loads, freeze-thaw cycles, or expansive soils requires rebar. Always check local building codes.
How long should I wait before walking on new concrete?
You can walk on most concrete after 24-48 hours. Light vehicle traffic is safe after 7 days when concrete reaches 70% strength. Do not apply full design loads until 28 days when concrete reaches 100% of its design strength. Cold weather extends these timelines - below 50°F, curing slows significantly.
What is a short-load fee for concrete delivery?
Ready-mix trucks hold 9-10 cubic yards. Orders under 5 cubic yards typically incur a short-load fee of $50-$125. For small projects, compare the total cost of bagged concrete versus a small ready-mix order plus delivery fee. Our calculator shows both options to help you decide.
Data Sources and Accuracy
- Concrete specifications: ACI 318-19 (American Concrete Institute)
- Material costs: NRMCA Ready Mixed Concrete Industry Data 2026
- Labor rates: Bureau of Labor Statistics, Construction Occupations (2026)
- Building codes: IBC 2024 (International Building Code)
- Bag yields: Quikrete and Sakrete manufacturer specifications
- Rebar standards: CRSI Manual of Standard Practice, 2021
📅 Last Updated:
Disclaimer: All results are estimates for planning purposes only. Actual quantities and costs may vary based on site conditions, local material pricing, and contractor rates. Always verify with your concrete supplier and local building department before ordering.
Your Privacy Matters
No personal data is stored, collected, or transmitted. All calculations run entirely in your browser. We do not use cookies to track inputs, and no project information is ever sent to our servers.