Shed-pad gravel volume = actual fill area (sq ft) × selected layer depth (in) / 324, in cubic yards. For a 10 × 12-foot shed with a selected 1-foot border on all sides, the pad is 12 × 14 ft. At a selected 6-inch layer depth, its net space is 84 cu ft, or 3.111111 cu yd. This is geometric volume, not automatically the loose delivered order or a verified tonnage.
Confirm the shed foundation requirements first
Site Prep, a shed-foundation contractor, gives a rule of thumb of extending gravel at least 12 inches beyond each side, with more width for extra-long eaves, and a general 4–6-inch gravel depth range.1 Those are that source’s general recommendations, not a universal foundation specification. Confirm the shed maker’s support, footprint, material and depth requirements and any local rules before ordering.
The pad dimensions used for quantity must be the actual gravel-fill dimensions. If a frame occupies part of the stated outer footprint, measure the inside fill space rather than counting the lumber as gravel. Border width, inside/outside dimensions and overhang allowance are separate inputs.
Net yardage by shed size: selected 1-foot border
For this comparison only, pad length = shed length + 2 ft and pad width = shed width + 2 ft. The table assumes those pad dimensions are the gravel-fill dimensions and a uniform selected depth. It does not account for lumber displacement, sloping ground or compaction conversion.
| Shed (ft) | Fill pad (ft) | Area (sq ft) | 4-in layer (cu yd) | 6-in layer (cu yd) |
|---|---|---|---|---|
| 6 × 8 | 8 × 10 | 80 | 0.988 | 1.481 |
| 8 × 8 | 10 × 10 | 100 | 1.235 | 1.852 |
| 8 × 10 | 10 × 12 | 120 | 1.481 | 2.222 |
| 10 × 10 | 12 × 12 | 144 | 1.778 | 2.667 |
| 10 × 12 | 12 × 14 | 168 | 2.074 | 3.111 |
| 12 × 12 | 14 × 14 | 196 | 2.420 | 3.630 |
| 12 × 16 | 14 × 18 | 252 | 3.111 | 4.667 |
| 12 × 20 | 14 × 22 | 308 | 3.802 | 5.704 |
Rounded display values only. These are net geometric volumes, not final supplier orders. The layer depths are comparison inputs, not instructions to use the same construction for every shed.
Formula and volume basis
- Area = actual inside fill length × actual inside fill width for a rectangle.
- Cu ft = area × layer depth (in) / 12.
- Cu yd = cu ft / 27 = area × depth (in) / 324.
- For varying depths, calculate non-overlapping sections and add unrounded volumes.
- Convert finished/compacted volume to loose order volume only with a defined material-specific relationship.
- Then apply any separate handling reserve and round to the actual sales increment.
FHWA’s earthwork guidance distinguishes undisturbed ground, loose material in transport and compacted fill. It calls for project-specific material information and a stated measurement basis.2 A blanket extra percentage does not establish how your supplied stone becomes the finished base. Do not combine a loose density with a compacted yardage and assume the order is complete.
Three checked examples
1. A 10 × 12-foot shed with selected border
With 1 ft on all sides: (10 + 2) × (12 + 2) = 168 sq ft. At a selected 6-inch layer depth: 168 × 6 / 12 = 84 cu ft = 3.111111 cu yd. At 4 inches: 56 cu ft = 2.074074 cu yd. Site Prep illustrates the same 84-cu-ft geometric calculation.1 The geometry alone does not state loose delivery volume.
2. Defined finished-to-loose conversion and order rounding
Suppose the 84-cu-ft target is a finished layer and project-specific information hypothetically confirms 1.15 loose yd per finished yd. Loose target = (84 / 27) × 1.15 = 3.577778 cu yd. A separately selected 5% handling reserve gives 3.756667 cu yd. If this supplier actually sells quarter-yard increments, round up to 4 loose cu yd. At a hypothetical confirmed 2,800 lb/loose yd, that rounded order weighs 11,200 lb = 5.6 US short tons. All factors and increments in this example are selected inputs, not recommended values for your site.
3. Frame outside dimensions versus fill dimensions
Suppose a rectangular frame measures 12 × 14 ft outside and its members occupy a hypothetical 6-inch width on every side. Inside fill dimensions = (12 − 1) × (14 − 1) = 11 × 13 ft = 143 sq ft. At a selected 6-inch layer depth, volume = 71.5 cu ft = 2.648148 cu yd. Using the outside area would count 12.5 cu ft of perimeter space that is not gravel. These are chosen dimensions; measure actual lumber and check that the resulting inside pad still meets the required shed clearance.
Tons require a matching density
Site Prep uses roughly 1.4 tons per cubic yard as a planning figure in its guide.1 It does not establish a measured density for your exact delivered material or a separate loose/finished basis for that factor. For this page’s weight math, specify US short tons (2,000 lb) and use matching supplier lb/yd. No reference factor is a safe vehicle-loading maximum.
For arithmetic only, 3.111111… matching yards at a selected matching 1.4 short tons/yd is 4.355556 short tons. That result is not the finished-to-loose example’s final 5.6-short-ton order. Net geometry, conversion, reserve and rounded sales quantity must not be presented as the same number.
Excavation depth is not automatically gravel thickness
A project may remove soil, set a frame above grade, or need different depths over a slope. Measure the intended gravel layer itself. This quantity page does not prescribe soil wetting, excavation depth, retaining construction or a universal fabric type. Confirm suitable site preparation, separation and drainage with the shed maker or foundation contractor.
FAQ
How much gravel for an 8 × 10 shed?
With the selected 1-ft border, a 10 × 12-ft fill pad is 120 sq ft. A selected 4-inch layer is 1.481481 cu yd; 6 inches is 2.222222 cu yd, before any defined conversion, reserve or sales rounding.
Should I automatically add 5–10%?
No universal percentage is established here. Identify any material conversion first. A handling reserve is separate, and an undefined “compaction percentage” is not enough.
Can I build a level pad on sloping ground using this table?
The table assumes uniform depth. Sloping ground changes the fill volume and can introduce retention, stability and drainage requirements. Get a site-specific foundation plan; adding one average depth is not a design.
Is the border the same for every shed?
No. The cited contractor’s 12-inch rule of thumb allows more for longer eaves.1 The actual shed requirements and fill footprint control the quantity.
Related tools and guides
Shed gravel pad calculator | Gravel calculator | Yards and US short tons converter | Gravel density reference chart | Shed-base material guide | Shed pad size chart
Sources
- Site Prep: How Much Gravel Do I Need for a Shed Foundation? (contractor border/depth guidance and 84-cu-ft example)
- Federal Highway Administration: Earthwork Design (volume states and project-specific estimating basis)