Shed Skid Foundation Calculator
A shed sitting on skids needs a compacted gravel pad underneath to stay level and drain properly. Enter your pad size and depth to get the tons or bags of base material you need.
Measure straight across the widest point.
A 4 in compacted gravel pad is standard for skid-mounted sheds
Covers spillage and compaction. 5–10% is normal.
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Bags or bulk delivery?
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Coverage & weight
Material profile
Volume starts with pad area times depth (converted from inches to feet) to get cubic feet, plus a waste percentage for compaction and spillage, then converted to cubic yards. Multiply cubic yards by the material’s weight per cubic yard (crushed run runs around 2,800 lb per cubic yard) and divide by 2,000 to get tons, then round up to a sensible order size since suppliers sell in half-ton or full-ton increments. Bagged material is estimated separately using standard 0.5 cu ft bags for smaller jobs or spot fills.
Recommended Gravel Depth by Project
Depth requirements change with what’s sitting on top of the gravel. A shed skid foundation needs less depth than a driveway base carrying vehicle loads.
| Project | Recommended Depth | Notes |
|---|---|---|
| Shed skid foundation | 4 in | Compacted crushed run under runners, level and well-drained |
| Walkway/path base | 2-3 in | Under pavers or as a standalone gravel path surface |
| Patio base | 4-6 in | Compacted in lifts under pavers or a concrete slab |
| Driveway base | 6-8 in | Deeper base needed to carry vehicle loads without rutting |
| Fence post footing backfill | As needed around post | Drainage layer below concrete, not a structural base depth |
Shed base material weight by type
| Type | Weight per yd³ | Best for | Drainage |
|---|---|---|---|
| Crushed run / road base | 2,800 lb | Compactable, standard shed base | Poor once compacted (by design) |
| Pea gravel | 2,600 lb | Good drainage under skids | Good, some fines |
Figures are for dry material. Wet or freshly delivered material can weigh noticeably more.
How to calculate base gravel you need
- Measure the length and width of the shed pad, including a few inches of overhang past the skids.
- Set depth typically 4 in of compacted crushed run for a skid foundation.
- Add waste for compaction settling and spillage during spreading.
- Convert cubic feet to cubic yards, then to tons using the material’s weight per cubic yard.
- Round up to the nearest order increment your supplier delivers in, or convert to bags for a small pad.
Worked example
A 12 x 10 ft shed pad at 4 in of compacted crushed run, with 10% waste added.
- Pad size12 x 10 ft = 120 sq ft
- Depth4 in
- Waste added10%
- Cubic feet needed44.0 cu ft
- Cubic yards1.63 cu yd
- Tons (crushed run at 2,800 lb/cu yd)2.28 tons
- Tons to order2.5 tons
- Delivered bulk cost$205.00
Recommended depth by project
| Project | Recommended depth | Notes |
|---|---|---|
| Shed skid foundation | 4 in | Compacted crushed run, level and well-drained under runners |
| Garden shed on blocks | 4-6 in | Slightly deeper base helps with support point stability |
| Small storage building | 4 in | Standard depth for lightweight structures on skids |
| Large shed/workshop base | 6 in | Heavier structures benefit from a deeper compacted base |
Bags or bulk delivery?
Bagged crushed run and gravel are convenient for small pads or top-off work, but they cost noticeably more per ton than bulk delivered material once you’re past roughly a ton. A standard shed pad in the 1-3 ton range is usually cheaper and faster to place as a bulk delivery, dumped close to the build site and moved by wheelbarrow, rather than hauling and opening dozens of individual bags.
- Under 1 ton: bags are often fineSmall pads or repair/top-off jobs can be handled with bagged material without much cost penalty.
- Over 1-2 tons: go bulk deliveredBulk pricing per ton drops well below bagged material once the job needs more than a ton or two.
- Check delivery access firstConfirm a dump truck can reach a spot close to the shed site before ordering bulk; bagged material may be the only option for tight access.
- Order a little extra either wayRounding up covers compaction loss and spillage regardless of whether you buy bagged or bulk.
Common mistakes
- Skipping compaction between liftsDumping the full depth of gravel and compacting only the surface leaves the base loose underneath, and it will settle unevenly once the shed’s weight is on it.
- Using pea gravel where firmness mattersPea gravel drains well but doesn’t lock together like crushed run, so skids can shift or sink over time without a firmer base material underneath.
- Not sizing the pad larger than the shed footprintThe gravel pad should extend a few inches past the skids on all sides so the shed isn’t sitting at the very edge of its foundation.
- Forgetting the waste allowance for compactionCompaction reduces loose volume, so ordering exactly the finished volume without a waste allowance usually comes up short.
What this calculator assumes
Adjust your result if your project differs from these.
- Pad area is entered as a simple rectangle matching the shed footprint plus overhang.
- Depth is the compacted finished depth, not the loose material depth before compaction.
- Material weight per cubic yard reflects the crushed run or pea gravel option selected.
- Waste percentage accounts for compaction settling and spillage during spreading.
- Tons to order are rounded up to a practical supplier increment (commonly the nearest half ton).
Common questions
How deep should gravel be under a shed?
4 in of compacted crushed run is a common standard for a shed skid foundation on reasonably stable, well-drained soil.
Should I use crushed run or pea gravel under a shed?
Crushed run compacts into a firm, stable surface and is the more common choice for skid foundations; pea gravel drains well but doesn’t lock together as firmly.
How many tons of gravel do I need for a shed pad?
It depends on pad size and depth; for a 12 x 10 ft pad at 4 in deep with crushed run, expect around 2.3 tons before rounding up to a delivery-friendly order size.
Can I use bagged gravel instead of bulk delivery?
For small pads it’s workable, but bagged material costs more per ton than bulk delivered material, so bulk usually makes more sense once you’re past a ton or two.
Do I need to compact the gravel pad?
Yes. Compacting in lifts with a plate compactor keeps the base firm and prevents uneven settling once the shed’s weight is sitting on the skids.
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materialcalculate.com/tools/shed-skid-foundation-calculator/
Project
| Shape | — |
| Dimensions | — |
| Depth | — |
| Area | — |
| Material | — |
| Waste allowance | — |
Volume & weight (incl. waste)
| Cubic yards | — |
| Cubic feet | — |
| Weight | — |
| Tons (rounded up) | — |
Shopping list
| Bulk order | — |
| Bagged alternative (0.5 cu ft) | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Assumes uniform depth and standard dry material densities. Confirm quantities with your supplier before ordering.