How Much Gravel Do You Need for a Shed Base?

Updated 2026-09-12 · Yardly

Plan on 4 inches of compacted crushed stone under a typical backyard shed (6–8 inches for larger sheds, wet ground, or a floating skid), and order about 20% more loose volume than the finished bed — crushed stone shrinks that much under a plate compactor. Add a 6–12 inch gravel apron around the walls so rainwater sheds instead of pooling against the timber.

Why a gravel base, not just dirt

Setting a shed on bare soil lets moisture wick into the floor and the ground heave or settle under it. A compacted stone base does three jobs: it lifts the shed off the damp ground, it drains, and it locks the structure in place so the skids don’t sink unevenly.

The gravel formula for a shed base

Measure the base footprint (shed size plus the apron), convert depth to feet, and add the compaction margin:

((Length + Apron) × (Width + Apron) × Depth ÷ 12) ÷ 27 × 1.20 = loose cubic yards

The ”÷ 12” turns depth in inches to feet; ”÷ 27” is cubic feet to cubic yards; ”× 1.20” is the compaction margin — dense-graded stone loses about 15–25% of its loose volume once compacted, so you order loose and finish at target depth.

The gravel calculator runs this from your exact dimensions and switches between yards and tons.

Depth by shed type

• Small shed (6×8 or under), stable soil: 4 inches compacted.
• Standard shed (8×12 to 12×16), average soil: 4–6 inches.
• Large shed, wet/clay soil, or a floating skid foundation: 6–8 inches, sometimes a geotextile fabric under it.

Guidance from the Interlocking Concrete Pavement Institute on granular bases puts structural stone well above the thin layers used for foot-traffic patios — a shed carries a concentrated load at each skid, so don’t skimp to patio depth.

The apron matters

Don’t size the gravel to the shed walls exactly. Extend the stone 6–12 inches beyond the footprint on every side. That apron sheds roof runoff away from the timber and stops the base edge from eroding into a lip. A 10×12 shed becomes roughly a 11×13 to 12×14 base once the apron is in.

Worked example: 10×12 shed, 4-inch base, 6-inch apron

• Base footprint: (10 + 1) × (12 + 1) = 143 sq ft
• × 4 in (0.333 ft) = 47.7 cu ft → ÷ 27 = 1.77 cu yd compacted
• × 1.20 compaction margin = 2.12 loose cu yd → order 2¼ yards

If that shed sits on clay, step up to 6 inches: 143 × 0.5 = 71.5 cu ft → ÷ 27 = 2.65 compacted → × 1.20 = 3.18 loose cu yd.

Most suppliers sell shed stone by the ton. At about 1.4 tons per loose cubic yard, the 4-inch job is roughly 3 tons, the 6-inch job about 4.5 tons.

Material choice

Use angular crushed stone (#57, #3/#4, or crusher run / road base) that interlocks when compacted. Skip pea gravel and river rock here — rounded stone never locks and the skids will migrate. If the ground is soft, lay geotextile fabric first so the stone doesn’t sink into mud.

Building it

Strip organic topsoil, spread the stone in 2–3 inch lifts, and compact each lift with a plate compactor before adding the next. Dumping the full depth and compacting once leaves the bottom loose, and a loose bottom settles later — dragging the shed down with it.

Keep reading

• Sizing the stone yardage from raw dimensions? The gravel calculator does the volume and ton conversion.
• Building up soft ground before the stone? The fill dirt calculator sizes the structural fill underneath.
• Same stone under a patio? The patio base guide covers the thinner 4-inch section and the sand layer on top.

Frequently asked questions