Shed & Workshop Slabs concrete calculator
Enter your dimensions — we'll size the load with a 10% waste factor. Typical shed & workshop slabs order: ~2 yd³.
How much concrete do you need?
Pick your project shape — we'll size the load.
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How the math works
length (ft) × width (ft) × thickness (ft) ÷ 27 = cubic yards
- 1 Multiply length by width in feet to get the area of the pour.
- 2 Convert thickness to feet (4 in = 0.33 ft) and multiply — that gives cubic feet.
- 3 Divide by 27 (the cubic feet in one cubic yard) to get cubic yards.
- 4 Add 10% waste for uneven ground and spillage, then round up to the quarter yard.
How to use this calculator
- 1 Measure the pour. Measure the length and width of the pour in feet, and pick the thickness in inches (4 in is typical).
- 2 Enter the dimensions. Type the numbers into the shed & workshop slabs calculator — it converts units and divides by 27 to get cubic yards.
- 3 Check the waste factor. The result includes 10% waste for uneven ground and spillage, rounded up to the quarter yard (1 yd³ minimum).
- 4 Price the delivery. Send the yardage with your ZIP code to get an all-in delivered price — metered trucks bill only what's actually poured.
Typical shed & workshop slabs quantities
Common shed and workshop pad sizes at 4 in thick (bump to 5–6 in if heavy machinery lives inside):
| Pad size | Thickness | Volume | Order (with waste) |
|---|---|---|---|
| 8 × 8 ft | 4 in | 0.79 yd³ | 1 yd³ |
| 8 × 10 ft | 4 in | 0.99 yd³ | 1.25 yd³ |
| 10 × 12 ft | 4 in | 1.48 yd³ | 1.75 yd³ |
| 12 × 16 ft | 4 in | 2.37 yd³ | 2.75 yd³ |
| 12 × 20 ft | 5 in | 3.70 yd³ | 4.25 yd³ |
Common ordering mistakes
-
Measuring the slab, not the forms
Measure inside the forms as they're actually set — a “10 × 12” shed & workshop slab pour is whatever the forms enclose, and an inch each way moves the total.
-
Trusting the ground to be flat
Florida sand settles and over-digs. If the sub-base dips half an inch across the pour, that missing volume comes out of your load — grade and compact before the truck arrives.
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Ordering the bare math
Skipping the waste factor is the classic way to come up half a wheelbarrow short. With a metered truck, rounding up costs nothing unless it's actually poured.
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Mixing up inches and feet
Thickness is the usual culprit: 4 inches is 0.33 feet. Feed the calculator inches where it asks for inches and it handles the conversion.
Frequently asked questions
How accurate does my estimate need to be?
Close is enough: metered trucks bill the actual yards poured to the nearest quarter yard. The calculator adds a 10% waste factor so you don't come up short.
Which mix should I use for shed & workshop slabs?
3000 PSI Standard Mix is the standard recommendation for shed & workshop slabs. The workhorse residential mix: shed slabs, patios, sidewalks and driveways in Florida's climate. Poured metered, on-site.
How thick should a shed slab be?
4 inches is the Florida standard for garden sheds and workshops. Go 5–6 inches if a tractor, lift or heavy machinery will sit on it — and consider fiber mix on sandy ground for crack control.
Delivered pricing by city
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Next step: read the Shed & Workshop Slabs guide or get your delivered price with the button above.