Pad length = shed length + 2 ft. Pad width = shed width + 2 ft. That is 1 foot of extra pad on every side. A 10 × 12-foot shed gets a 12 × 14-foot pad, or 168 square feet.1, 2 Builders disagree on depth, stone and how level the pad must be, so check the sheet for the shed you are buying before you dig.
Shed base size chart
Pad size for each common shed size, using 1 foot of extra pad on every side. This is the figure White Pine, Liberty Sheds and Affordable Storage Sheds each give in their own wording. Some builders ask for more or less, and the chart is not a permit, setback or engineering check.
| Shed (ft) | Pad (ft) | Pad area (sq ft) |
|---|---|---|
| 6 × 8 | 8 × 10 | 80 |
| 8 × 8 | 10 × 10 | 100 |
| 8 × 10 | 10 × 12 | 120 |
| 10 × 10 | 12 × 12 | 144 |
| 10 × 12 | 12 × 14 | 168 |
| 12 × 12 | 14 × 14 | 196 |
| 12 × 16 | 14 × 18 | 252 |
| 12 × 20 | 14 × 22 | 308 |
Use the actual outside size of the shed, not the model name. For gravel quantities by pad size, see how much gravel for a shed base.
“1 ft larger” and “2 ft larger” mean the same pad
White Pine says the pad should be 1 foot larger than the shed on all sides and gives the example of a 10 × 12 shed on a 12 × 14 pad.1 Liberty Sheds says the stone pad should be at least 2 feet longer and 2 feet wider than the shed.2 Affordable Storage Sheds also asks for a pad 2 feet wider and 2 feet longer, which it describes as a 1-foot perimeter that keeps dirt from splashing onto the walls.3 These are the same pad. One counts per side, the other counts the total. Read your builder’s wording carefully so you do not build a pad 2 feet bigger per side by mistake, or a pad only 1 foot bigger in total.
What the three builder sheets say
| Builder | Pad size | Other requirement we read |
|---|---|---|
| White Pine Structures | 1 ft larger than the shed on all sides1 | Strip 4-6 in of topsoil; exposed soil level within 2 in; 3/4-in clean crushed stone, not pea gravel or river stone1 |
| Liberty Sheds | At least 2 ft longer and 2 ft wider2 | Perfectly level, square, no voids or rises; 3/4-in crushed stone, not smooth or river stone2 |
| Affordable Storage Sheds | 2 ft wider and 2 ft longer3 | 4-6 in gravel base of #57 stone or clean crusher run; the pad must be flat and level or the shed warranty is voided3 |
These are three builders, not every builder. An American Rock Supply review of more than twenty builder and dealer site-prep sheets reports that most ask for about 12 inches of margin per side, but also that depth, stone and level tolerance vary widely.4 That is a supplier’s summary. We checked the three sheets above directly and did not verify the rest. A shed delivered on a different brand may have a different rule.
Why the extra foot matters
Affordable Storage Sheds gives splash-back as its reason: the foot of perimeter keeps dirt from splashing onto the sidewalls.3 Liberty says the larger pad helps drainage and keeps vegetation, and the moisture it holds, away from the shed.2 Site Prep, a shed-foundation contractor, gives the same 12-inch rule and says to add more width if the eaves are long.5 None of these says the foot is a structural requirement. Treat it as the builders’ standard margin.
Three checked examples
1. A 10 × 12-foot shed
Pad = (10 + 2) × (12 + 2) = 12 × 14 = 168 sq ft. Border area = 168 − 120 = 48 sq ft, the 1-foot ring around the shed.
2. A shed that is a little bigger than its model name
Suppose a “10 × 12” shed actually measures 10 ft 4 in × 12 ft 4 in outside. That is 10.3333 × 12.3333 ft. Pad = 12.3333 × 14.3333 = 176.78 sq ft, about 9 sq ft more than the model-name pad. These dimensions are an example, not a statement about any brand. Measure the real shed or ask the builder for the footprint.
3. Which side do you add to?
A 12 × 16 shed on a “2 ft longer and wider” pad is 14 × 18 = 252 sq ft. If you mistakenly add 2 ft on every side you get 16 × 20 = 320 sq ft, which is 68 sq ft and about 27% more pad than the builder asked for. That would also be more stone to buy, so read the wording first.
Before you dig
- Get the shed maker’s site-prep sheet and check pad size, depth, stone and the allowed out-of-level amount.
- Measure the shed’s real outside footprint.
- Check permits, setbacks and utility locations. White Pine points out that many townships have setback rules and that 811 locates underground utilities for free.1
- Ask whether a frame is needed. White Pine and Liberty both describe a treated-lumber perimeter, and the frame width changes the fill area.1, 2
FAQ
How much bigger should a shed pad be than the shed?
The three builders we read ask for about 1 foot on every side, which is 2 feet longer and 2 feet wider overall.1, 2, 3 Confirm your own builder’s number.
Does a shed pad need to be the same size as the shed?
Our sources do not support that for gravel pads. They all ask for a margin beyond the walls. A different foundation, such as a concrete slab, has its own requirements and is outside this guide.
How deep should the gravel be?
Affordable Storage Sheds suggests 4 to 6 inches,3 and White Pine says to strip 4 to 6 inches of topsoil before building the pad.1 Those are two different numbers for two different steps. Check your builder for the finished depth.
Related tools and guides
Gravel for a shed base | Best gravel for a shed base | Gravel calculator | Square footage calculator
Sources
- White Pine Structures: How to Prep Your Site for a Shed (1 ft larger on all sides, 10 × 12 on 12 × 14 example, topsoil strip, level within 2 in, stone type, frame, setbacks and 811)
- Liberty Sheds: Shed Delivery (pad at least 2 ft longer and 2 ft wider, level and square, 3/4-in crushed stone, frame)
- Affordable Storage Sheds: Gravel Foundation (pad 2 ft wider and longer, 4-6 in base, #57 or crusher run, warranty and level note)
- American Rock Supply: Gravel Pad for a Shed (a supplier’s review of builder site-prep sheets, July 2026; secondary source)
- Site Prep: Why Your Gravel Shed Foundation Should Be 12 in. Wider (shed-foundation contractor, 12-inch margin rule; we saw it only in search results)