How Much Gravel for a Shed Base (8x8 to 16x20 Pads)

A 12x12 gravel pad, the right size for a 10x10 shed, takes 4.29 tons of stone at 6 inches deep, about 3.07 cubic yards with a 15 percent compaction buffer, or $193 of material at $45 a ton. At 4 inches it is 2.86 tons. A 16x20 pad for a 14x18 shed runs 9.54 tons at 6 inches. Every figure below is for the pad, a foot bigger than the shed on each side.

Length (ft)

Width (ft)

Depth (in)

Compaction buffer

Decorative / path (5%)Driveway / load-bearing (15%)Custom

Density (tons / cu yd)

Price per ton ($ (optional))

Cubic yards

3.11 cu yd

With buffer

3.58 cu yd

Tons (with buffer)

5.0 tons

Estimated cost

—

Includes a 15% compaction buffer. Order in whole or half-yard increments. Round up to the nearest your supplier offers.

The calculator is set to a 12x14 pad at 6 inches, which is the pad for a 10x12 shed, one of the most common sizes sold. That pad falls between two rows of the tables below, so the widget is the place to read its tonnage.

Marking out: the pad is a foot bigger than the shed each way

The pad is not the shed footprint. It runs a foot past the shed walls on every side, so a 10x12 shed sits on a 12x14 pad and an 8x8 shed on a 10x10. The extra foot is doing several jobs at once. Rain coming off the eaves lands on stone instead of carving a gutter in the soil along the wall. The floor skids sit fully on gravel even when the delivery crew sets the shed a few inches off center. There is room to walk around with a mower. And the frame can be an inch out of square without the shed hanging over the edge. A shed with wide eaves, or one that will have a ramp, gets more on those sides; 2 feet is common at the door.

Shed footprint	Pad to mark out
6x6	8x8
6x8	8x10
6x10	8x12
8x8	10x10
8x10	10x12
8x14	10x16
10x10	12x12
10x12	12x14 (between two table rows; the calculator above is preset to it)
10x14	12x16
10x18	12x20
12x18	14x20
14x18	16x20

Mark the pad with stakes and string at the pad size, not the shed size, and square it by measuring the two diagonals until they match. On a 12x14 pad both diagonals should read the same to within half an inch; if they do not, the rectangle is a parallelogram and the shed will show it at the corners. Mark the dig line a few inches outside the string so there is room to set the frame.

Digging out: the hole is the same volume as the stone

Strip the sod and topsoil across the whole pad to the full depth you are building, 4 or 6 inches, plus a little so the frame can sit an inch or two proud of the surrounding ground and shed water away. Do not leave the sod in place under the stone; it rots, and a soft strip under one skid is how a shed ends up with a door that will not latch.

The spoil pile is bigger than people expect. A 12x12 pad dug 6 inches deep produces 2.67 cubic yards of soil and sod, which is the same figure as the stone volume before its buffer, because the hole and the fill are the same shape. The topsoil calculator will tell you how far that spreads if it is going on a bed or a low spot, and it is worth deciding where before the first shovel goes in, since 2.67 cubic yards does not fit in a wheelbarrow.

On a slope, cut into the high side rather than building up the low side with stone; stone piled above grade spreads under load. If the high side ends up with a soil face much over a foot, that is a small retaining wall and a different job. A pad that falls a fraction across its length is fine for drainage, but the shed floor wants to be level, so the frame is set level and the stone is screeded to the frame.

Four inches or six: decide by what rolls through the door

Four inches of compacted stone carries a garden shed: hand tools, bicycles, bags of potting mix, a push mower. It is the depth for the 8x8 and 10x10 pads with a light shed on them and firm, well-drained soil underneath.

Six inches is for anything you will drive or push in that is heavy. A riding mower, an ATV, a motorcycle, a workshop with a bench and a drill press, a 10x12 or larger shed with a loft full of boxes. It is also the depth for clay, for ground that stays wet after rain, and for the bigger sheds regardless of contents, because a 14x18 shed puts 252 square feet of floor, and whatever is stacked on it, onto the pad.

Four inch pads

Pad	Fits a shed up to	Cubic yards with 15% buffer	Tons at 1.4 per yard	Material at $45 a ton
8x8	6x6	0.91	1.27	$57
8x10	6x8	1.14	1.59	$72
8x12	6x10	1.36	1.91	$86
10x10	8x8	1.42	1.99	$89
10x12	8x10	1.70	2.39	$107
10x16	8x14	2.27	3.18	$143
12x12	10x10	2.04	2.86	$129
12x16	10x14	2.73	3.82	$172
12x20	10x18	3.41	4.77	$215
14x20	12x18	3.98	5.57	$250
16x20	14x18	4.54	6.36	$286

Six inch pads

Pad	Fits a shed up to	Cubic yards with 15% buffer	Tons at 1.4 per yard	Material at $45 a ton
8x8	6x6	1.36	1.91	$86
8x10	6x8	1.70	2.39	$107
8x12	6x10	2.04	2.86	$129
10x10	8x8	2.13	2.98	$134
10x12	8x10	2.56	3.58	$161
10x16	8x14	3.41	4.77	$215
12x12	10x10	3.07	4.29	$193
12x16	10x14	4.09	5.72	$258
12x20	10x18	5.11	7.16	$322
14x20	12x18	5.96	8.35	$376
16x20	14x18	6.81	9.54	$429

Some rows repeat across the two tables, and that is not a typo. An 8x12 pad at 6 inches holds exactly the same stone as a 12x12 pad at 4 inches, 2.04 cubic yards after the buffer, because 96 square feet at 6 inches and 144 square feet at 4 inches are the same volume. The 8x8 at 6 inches matches the 8x12 at 4, and the 10x16 at 6 matches the 12x20 at 4, for the same reason.

The dollar column is material at the yard at $45 a ton, a typical 2026 figure for crusher run or clean stone in much of the US; local prices run from well under that to well over it, and delivery is on top. The gravel calculator takes your quoted price per ton and the product’s real density if either differs.

Crusher run or clean stone: both camps have a point

Walk into a stone yard and ask for shed base and you will get one of two products, and the yard will be sure theirs is right.

Crusher run, 3/4 inch minus. Crushed stone with everything from 3/4 inch pieces down to dust. The fines fill the gaps between the pieces, so a plate compactor turns it into something close to a paved surface. The frame cannot shift in it, the skids cannot shift on it, and a shed set on it stays where it was put. The cost is water. Fines hold moisture, the surface stays damp after rain, and the stone wicks a little of it up toward the floor joists. On ground that already drains badly, that is a floor that never fully dries.

Clean stone, #57 or 3/4 inch washed. The same crushed rock with the fines screened out. Water goes straight through it and the top dries within an hour of the rain stopping, there is nothing to wick, and the floor sits over what is in effect an air gap. Shed delivery companies tend to ask for it because they can rake it level and set a shed in minutes. What it will not do is lock. A plate compactor seats it but it stays a loose bed of stones, so the frame has to contain it, and a shed with no skids can walk a little over years of door slams and mower trips.

Each camp is answering a different question. If the site is wet, or the floor is wood joists close to the stone, drainage matters more and clean stone wins. If the shed is heavy, the ground is dry and firm, or there will be a ramp and a mower crossing it daily, the compacted surface wins. A common compromise is crusher run for the bottom lift, compacted hard, and 2 inches of clean stone raked over the top: a firm bed with a dry surface. The gravel calculator page carries the density of each product and the longer version of the argument.

One number does change with the choice. The tables assume 1.4 tons per cubic yard. Crusher run with its fines usually weighs more than that, washed stone with its voids a little less, so the ton figure for the same pad moves by a few hundred pounds either way. Ask the yard for the density of what you are buying and put it in the calculator; the cubic yards stay the same, the tons do not.

The frame: pressure-treated timber, staked and set level

The frame holds the stone in and sets the finished height, and its outside dimension is the pad size. Pressure-treated 4x4s are the usual choice for a 4 inch pad: a 4x4 is 3 1/2 inches tall, so the stone finishes flush with the top or a hair above. For a 6 inch pad use 4x6 on edge or 6x6, both 5 1/2 inches, or stack two 4x4s and screw them together. Buy ground-contact rated lumber; the frame sits in wet stone for the life of the shed.

Join the corners with long structural screws or a half-lap, then drive stakes on the outside every 3 or 4 feet and screw the frame to them. Two-foot lengths of rebar driven through holes in the timber do the same job and never rot. Set the frame level in both directions with a long level or a line level on the string, and check the diagonals again once it is fastened, because screwing the corners is where a square frame goes out of square.

The frame is four pieces of lumber and does not need a cut list. If you are building the shed itself on top of the pad rather than taking delivery of one, the framing calculator does the stud count for its walls.

Weed barrier goes under the stone, lapped up the frame

Lay a non-woven geotextile across the dug-out pad after the frame is in, run it up the inside face of the frame and staple it near the top. Overlap any seams by a foot. The cheap woven landscape fabric from a garden center does the weed part of the job; the heavier non-woven does the other part, which is keeping the stone from working down into the soil over years of wet and dry cycles until the pad is half its depth. On clay or soft ground that second job is the one that matters. The fabric is not a drainage layer and not a substitute for depth.

Compacting in lifts, and what the 15 percent buffer covers

Crusher run goes in two lifts of about 3 inches, each one compacted with a rented plate compactor while the stone is damp. Trying to compact 6 inches at once leaves the bottom half loose. Make overlapping passes in both directions, rake out the low spots that show up after the first pass, and compact again. The second lift is where the level gets set: screed it with a straight 2x4 riding on the frame, fill the hollows, and compact once more.

Clean stone does not compact in the same sense. A plate compactor or a hand tamper seats it and knocks the high spots down, and then it is as dense as it is going to get. Rake it to the frame, screed, and check the level.

The 15 percent in the tables is what turns the loose delivery into the finished depth. It covers the volume that disappears under the compactor in crusher run, the stone that settles into the fabric and the soil, and the shovelful that ends up in the lawn on every trip. With clean stone most of the loss is the settling rather than compaction, and the buffer still gets used. The material waste factors guide is where the difference between a compaction allowance and a waste allowance is set out, and a shed pad is a case that needs the first far more than the second.

Tons or cubic yards: how the yard will quote it

You measure the pad in feet and inches and come up with cubic yards. The yard sells by the ton, because the loader drops stone into a truck that gets weighed on the way out. The tables carry both so the conversion is already done, at 1.4 tons per cubic yard, and the cubic yards to tons guide has the figure for other materials if the same delivery is bringing sand or topsoil.

Round the tonnage up to whatever the yard sells in, usually a half ton or a whole ton. The 12x12 pad at 6 inches is 4.29 tons; ask for 4 1/2 and you will have a wheelbarrow or two spare for the low corner. Stone that has sat in the rain weighs more per yard than dry stone, so a ton bought wet is a little less stone than a ton bought dry, which is one more reason to round up rather than down. For a pad of an unusual shape, or two matching pads on one delivery, the cubic yard calculator takes the dimensions in any unit and reports tons beside the yards at the same 1.4 the tables use.

Delivery minimums and the small-pad problem

An 8x8 pad at 4 inches is 1.27 tons and $57 of stone, and the delivery charge for that 1.27 tons will typically be more than the stone. Delivery is priced per trip, commonly somewhere in the $50 to $150 range for a local run, and plenty of yards set a minimum order of a few tons or charge a flat fee below it.

That changes the arithmetic on the small pads. Going from 4 inches to 6 on the same 8x8 pad adds 0.64 tons and $29 at $45 a ton, which is less than almost any delivery fee, so if the truck is coming anyway the deeper pad is close to free. Combining the order with something else from the same yard, a driveway top-up or a path, spreads the delivery charge; the gravel for a driveway guide sizes that second load. For the very smallest pads the other route is hauling it yourself: a half-ton pickup is rated for roughly 1,000 to 1,500 lb in the bed, check the sticker on the door jamb, so the 8x8 pad at 4 inches is two or three trips with a shovel. Bagged stone from a home center is the last resort: the 0.91 cubic yards for that pad is about 25 cubic feet, which in half-cubic-foot bags is a lot of lifting for a worse price.

Above about 2 tons, delivery wins every time, and the question becomes where the truck can drop it. A pile on the driveway 30 feet from the pad is 4 tons of wheelbarrow trips, so clear a spot as close to the frame as the truck can reach.

When a concrete slab is the better floor

A gravel pad is cheaper than a slab, drains, needs no cure time, can be built in an afternoon with a rented compactor, and if the shed ever moves the stone can be raked out and used elsewhere. For most prefab and kit sheds it is the right base. A slab wins where the floor itself has to be the floor: a workshop with machinery that wants to be bolted down, a shed that doubles as a garage, a space that has to stay rodent-proof, or a site where a wood floor over gravel would sit too close to standing water. The concrete for a shed slab guide prices the slab for the same 8x8 to 16x20 footprints and the concrete calculator gives the bag count or the ready-mix order for whatever size you land on. Either way, check with your local building department before you dig, because some jurisdictions treat the pad as part of a permitted structure above a certain shed size.