How Much Road Base for a 12x20 Shed Base?
A 12 by 20 foot shed base is 240 square feet. How much road base for a 12x20 shed base depends on depth: at 4 inches it is about 2.96 cubic yards or 4.4 tons. Suppliers usually sell by the ton, so the tonnage is the number to give them.
Volume and tonnage calculator →The math for a 12x20 shed base
- Area: 12 × 20 = 240 sq ft.
- Depth in feet: 4 ÷ 12 = 0.333 ft.
- Cubic feet: 240 × 0.333 = 80.0 cu ft.
- Cubic yards: ÷ 27 = 2.96 yd³.
- Tons: × 1.5 = 4.4 tons.
The volume and tonnage calculator does this for any size.
Road base needed by depth
| Depth | Cubic yards | Tons (approx.) | Tons +10% |
|---|---|---|---|
| 4 in | 2.96 | 4.4 | 4.9 |
| 6 in | 4.44 | 6.7 | 7.3 |
| 8 in | 5.93 | 8.9 | 9.8 |
About road base
Road base (also called base rock, ABC, or Class 2 base in different states) is a graded mix of stone and fines made to compact into a load-bearing layer. Weight per yard is a planning number; the scale ticket at the yard is the real one.
Preparing the shed base
Level the footprint, extend the stone a foot or so beyond the shed walls for drip and drainage, and compact in lifts. A timber or block border holds the pad shape. Since the shed base carries a shed floor frame, a little extra depth is cheap insurance.
Ordering tips
- Round up. Compaction and uneven ground eat material. Adding about 10 percent is common.
- Delivery size. 4.9 tons fits in a single typical dump truck load; small loads may carry a delivery fee. See how many tons of gravel in a dump truck.
- Bulk vs bags. At this size bulk delivery is usually the practical choice.
- Where it drops. Have the truck dump as close to the shed base as firm ground allows.
When to choose road base
Works well for:
- Base under asphalt and concrete
- Gravel roads and drives
- Equipment and shed pads
Less suited to:
- Drainage layers
- Decorative surfaces
- Surfaces that will stay uncompacted
Quick reference numbers
- Per inch over 100 sq ft: about 0.46 tons of road base (0.31 cubic yards).
- Per inch over 1,000 sq ft: about 4.6 tons.
- Another size for comparison: a 20x25 area at 2 inches takes about 4.6 tons.
- Weight used here: about 1.5 tons per cubic yard.
Where estimates go wrong
- Measuring only the main rectangle. Aprons, turnouts and curved edges add real square footage.
- Ordering exactly the math. Uneven ground and spillage nearly always need a little more than the flat calculation.
- Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.
- Forgetting that compaction shrinks loose material. A loose 4-inch spread of a dense-graded stone may finish closer to 3 inches after rolling.
Questions people ask
How many tons of road base for a 12x20 shed base?
About 4.4 tons at 4 inches deep, or 4.9 tons with 10 percent extra.
How many cubic yards is a 12x20 shed base at 4 inches?
About 2.96 cubic yards.
How much does a cubic yard of road base weigh?
Usually around 1.4 to 1.65 compacted tons, depending on stone size, fines and moisture.
How deep should road base be for a shed base?
The table above shows 4 to 8 inches. Shallower depths suit top dressing; deeper depths suit new installs and heavier use.
How many square feet is 12x20?
240 square feet.
Related guides
- Crushed Stone vs Gravel: Differences and Best Uses
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Many Tons of Gravel in a Dump Truck? Loads and Coverage
- How Much Does a Ton of Gravel Cover? Depth Chart
- How Much Road Base for a 12x14 Shed Base?
- How Much Road Base for a 12x16 Shed Base?
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