Trade Engine 01 • Flatwork & Slabs
Concrete & Slab Material Calculator
Calculate exact cubic yards, 80lb/60lb bags, rebar grid rods (#4 @ 12" O.C.), gravel sub-base tonnage, and vapor barrier rolls with one-click PDF takeoff export.
BT-CONC-1048•Oct 15, 2026•Concrete Flatwork & Slabs
Concrete Slab Takeoff & BOM
01
Project Dimensions & Specs
Client-side reactive engine. Adjust parameters to recalculate quantities immediately.
ft
ft
in
Standard Thickness Presets:
Safety Waste Allowance:
02
10×10×4"Takeoff Schedule Summary
| Item | Quantity | Unit | Est. Cost |
|---|---|---|---|
| Ready-Mix (4000 PSI) | 1.36 | yd³ | $197 |
| ↳ Bag alternative | 62 | 80-lb | ($403) |
| #4 Rebar Grid (12" OC) | 13 | 20' sticks | $189 |
| Crushed Stone Base (4") | 1.9 | tons | $67 |
| 10-Mil Vapor Barrier | 1 | roll(s) | $135 |
Estimated Material Takeoff:$761 – $973
Subcontractor Flatwork Labor (~$1.35):~$1,027
Estimated Project TotalTurnkey materials + installation
$1,788 – $2,287
Interactive CAD Plan View
Scale: Dynamic Proportional#4 Rebar @ 12" O.C.
Crushed Base Incl.
Logistics: Bagged Mix (on-site batch drum)
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Complete Job-Site Bill of Materials (BOM)
Material Takeoff & Accessory Checklist
Click any unit price to customize for your local supplier costs.
Markup:
Sales Tax:
← Swipe to view all 6 columns →7 Line Items
| Item / Specification | Category | Quantity | Unit Price | Total Est. | Supplier / Order |
|---|---|---|---|---|---|
80 lb High-Strength Concrete Mix Bags Quikrete or Sakrete 4000 PSI commercial grade mix | primary | 62 bags | $388 | Home Depot | |
#4 (1/2") Grade 60 Rebar (20 ft Sticks) Grid reinforcement spaced 12" on-center both ways | accessory | 13 pieces (20') | $189 | Home Depot | |
Rebar Tie Wire (Pack of 500 loop ties) 16-gauge bar ties for intersections + manual tie twister | fastener | 1 packs | $20 | Amazon | |
Heavy Duty Rebar Chairs (2" - 3" height) Maintains proper concrete cover above ground | accessory | 13 units | $12 | Local Supplier | |
Crushed Stone Base (#57 or 3/4" Crusher Run) 4" compacted sub-base for drainage and stability | accessory | 1.9 tons | $80 | Local Supplier | |
10-Mil Heavy Duty Polyethylene Vapor Barrier 10' x 100' roll, prevents capillary moisture ingress into slab | accessory | 1 rolls | $135 | Home Depot | |
1/2" x 4" Foam Expansion Joint Strips Perimeter expansion buffer for sidewalks, footings, and walls | accessory | 1 rolls (50') | $22 | Local Supplier |
Values update live with local price adjustments. Click unit prices to match your quotes.
Calculated Grand Total
$846
Engineering Methodology
Calculation Mechanics: Concrete Slab & Sub-Base
Formulas adhere to ASTM standards, ACI 318 guidelines, and standard construction estimating practice.
\ ext{Volume (cu yd)} = \ rac{\ ext{Length (ft)} \ imes \ ext{Width (ft)} \ imes \ rac{\ ext{Depth (in)}}{12}}{27} \ imes (1 + \ ext{Waste \%})
Step-by-Step Derivation Breakdown:
- 1Convert depth to feet: 4 inches ÷ 12 = 0.333 ft.
- 2Calculate raw slab volume: 10 ft × 10 ft × 0.333 ft = 33.33 cu ft.
- 3Convert to cubic yards: 33.33 ÷ 27 = 1.235 cu yds.
- 4Apply 10% safety allowance for uneven subgrade and form deflection: 1.36 cu yds total.
- 5Calculate 80-lb pre-mixed bags: 1.36 cu yd ÷ 0.0222 cu yd/bag = 62 bags.
- 6Calculate #4 rebar grid @ 12" on-center: 13 pieces (20ft rods) = ~260 linear feet.
Field Inspection & Trade Best Practices
- For driveways and slabs taking vehicle loads, 4000 PSI concrete at 5" minimum thickness with #4 rebar is recommended over unreinforced 3.5" flatwork.
- Pouring over a compacted 4" crushed gravel sub-base prevents slab settling, frost heave, and cracking.
- Place control joints at intervals no greater than 2.5 to 3 times the slab thickness in feet (e.g., maximum 10-foot spacing for a 4" slab).
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Concrete Takeoff
1.36 cu yd$761 - $973
Standard Slab Sizes & Pre-Computed Takeoffs
Instant answers for standard residential and commercial slab dimensions:
10×10 Slab
1.36 cu yd • 62 bags (80 lb)
Shed / Patio Favorite
10×10 Slab
2.04 cu yd • 92 bags (80 lb)
Heavy Equipment Pad
12×12 Slab
1.96 cu yd • 89 bags (80 lb)
Gazebo / Hot Tub Pad
12×12 Slab
2.93 cu yd • 132 bags (80 lb)
Vehicle Slab
8×8 Slab
0.87 cu yd • 40 bags (80 lb)
Storage Shed Pad
8×10 Slab
1.09 cu yd • 50 bags (80 lb)
Generator / AC Pad
10×12 Slab
1.63 cu yd • 74 bags (80 lb)
Workshop Foundation
10×16 Slab
2.17 cu yd • 98 bags (80 lb)
Patio Slab (4-inch)
10×16 Slab
3.26 cu yd • 147 bags (80 lb)
Heavy Machinery Slab
10×20 Slab
2.72 cu yd • 123 bags (80 lb)
Single Car Carport
10×30 Slab
4.07 cu yd • 184 bags (80 lb)
Driveway Extension
12×14 Slab
2.28 cu yd • 103 bags (80 lb)
Extended Patio
12×16 Slab
2.61 cu yd • 118 bags (80 lb)
Backyard Workshop
12×20 Slab
3.26 cu yd • 147 bags (80 lb)
Single Car Garage Slab
12×24 Slab
3.91 cu yd • 176 bags (80 lb)
Extended Carport
12×28 Slab
4.56 cu yd • 206 bags (80 lb)
RV Parking Pad
14×14 Slab
2.66 cu yd • 120 bags (80 lb)
Large Covered Patio
14×20 Slab
3.8 cu yd • 171 bags (80 lb)
Workshop Addition
14×24 Slab
4.56 cu yd • 206 bags (80 lb)
Boat Storage Slab
16×16 Slab
3.48 cu yd • 157 bags (80 lb)
Outdoor Living Patio
16×20 Slab
4.35 cu yd • 196 bags (80 lb)
Detached Workshop
16×24 Slab
5.21 cu yd • 235 bags (80 lb)
2-Car Compact Garage
16×32 Slab
6.95 cu yd • 313 bags (80 lb)
Pool Apron & Deck
18×20 Slab
4.89 cu yd • 221 bags (80 lb)
2-Car Attached Garage
18×24 Slab
5.87 cu yd • 265 bags (80 lb)
2-Car Standard Garage
20×20 Slab
5.43 cu yd • 245 bags (80 lb)
2-Car Garage Slab (4-inch)
20×20 Slab
8.15 cu yd • 367 bags (80 lb)
2-Car Garage Slab (6-inch)
20×24 Slab
6.52 cu yd • 294 bags (80 lb)
Standard 2-Car Garage
20×30 Slab
8.15 cu yd • 367 bags (80 lb)
3-Car Garage / Shop
24×24 Slab
7.82 cu yd • 352 bags (80 lb)
Oversized 2-Car Garage
24×24 Slab
11.73 cu yd • 528 bags (80 lb)
Heavy Duty Workshop
24×30 Slab
9.78 cu yd • 441 bags (80 lb)
Detached 3-Car Garage
24×36 Slab
11.73 cu yd • 528 bags (80 lb)
Commercial 3-Bay Garage
24×40 Slab
16.3 cu yd • 734 bags (80 lb)
Pole Barn Foundation
30×30 Slab
12.22 cu yd • 550 bags (80 lb)
Barndominium / Pole Barn
30×30 Slab
18.33 cu yd • 825 bags (80 lb)
Commercial Equipment Slab
30×40 Slab
20.37 cu yd • 917 bags (80 lb)
Shop / Agricultural Barn
30×50 Slab
30.56 cu yd • 1376 bags (80 lb)
Commercial Steel Building
40×40 Slab
32.59 cu yd • 1467 bags (80 lb)
Commercial Metal Building
40×60 Slab
48.89 cu yd • 2201 bags (80 lb)
Industrial Warehouse Slab
4×20 Slab
0.95 cu yd • 43 bags (80 lb)
Front Entry Walkway
4×50 Slab
2.38 cu yd • 108 bags (80 lb)
Long Perimeter Sidewalk
Frequently Asked Concrete Questions
How do I calculate concrete for a slab?
Multiply length (ft) × width (ft) × depth (converted to ft by dividing inches by 12). Divide that total cubic feet by 27 to get cubic yards. Finally, add 10% safety buffer for uneven ground and spillage.
How many 80 lb bags of concrete make a cubic yard?
It takes exactly 45 bags of 80 lb concrete mix to equal one cubic yard (27 cubic feet). For 60 lb bags, you need 60 bags per cubic yard.
At what point should I order a concrete truck instead of bags?
When your required volume exceeds 2.5 to 3 cubic yards (~115 to 135 eighty-pound bags), ready-mix transit truck delivery is significantly faster, structurally more consistent, and usually 30-40% cheaper than buying bags.