Free online tool • Pad edge included
Gravel Pad Calculator
This gravel pad calculator sizes the gravel for a shed pad, RV or camper pad, parking pad, hot tub pad or AC unit pad. Enter the footprint of what sits on the pad, choose how far the gravel should extend past it, and get tons, cubic yards, bags and cost.
How Much Gravel for a Pad?
Gravel Pad Size and Depth
A gravel pad should be larger than whatever sits on it. Extending the gravel 12 inches past the footprint on every side keeps rain dripping off the roof from washing out the edges, gives you a clean place to step, and stops the corners from sinking. The gravel pad calculator adds this margin for you: a 10 × 12 ft shed becomes a 12 × 14 ft gravel pad.
| Gravel pad | Typical size | Gravel depth | Tons of crusher run* |
|---|---|---|---|
| 8 × 10 shed pad | 10 × 12 ft | 4 in | 2.6 |
| 10 × 12 shed pad | 12 × 14 ft | 4 in | 3.6 |
| 12 × 16 shed pad | 14 × 18 ft | 4 in | 5.4 |
| Hot tub pad (8 × 8) | 10 × 10 ft | 4 in | 2.1 |
| Parking pad (10 × 20) | 12 × 22 ft | 6 in | 8.4 |
| RV pad (12 × 40) | 14 × 42 ft | 6 in | 18.8 |
*Including a 15 percent compaction allowance.
Gravel Pad Depth by Use
Shed pads
4 inches of compacted crusher run is enough for most garden sheds on firm soil; go to 6 inches for large sheds, workshops or clay. The gravel pad should be level, so on a slope it will be deeper on the low side — use the average depth in the calculator.
RV and parking pads
Vehicles need 6 inches of compacted gravel at minimum, and 8 to 12 inches for heavy motorhomes or soft ground, laid in lifts over geotextile fabric.
Hot tub and AC pads
A filled hot tub weighs several tons, so the gravel pad must be firm and dead level. Use 4 inches of compacted crusher run or 3/4 minus, and check the manufacturer's requirements — some warranties require a concrete slab instead.
Best Gravel for a Pad
Crusher run and 3/4 minus are the best gravel pad materials because their fines lock the stone into a hard, flat surface. Clean #57 stone drains faster and suits shed pads in wet areas, but it stays a little loose underfoot. Recycled concrete is the budget choice and performs like crusher run. Avoid pea gravel: the round stones roll, so blocks and wheels sink and the pad never stays level.
How the Gravel Pad Calculator Works
1. Add the margin
Add twice the edge margin to each dimension. A 10 × 12 ft shed with a 12 inch margin needs a 12 × 14 ft pad, or 168 sq ft.
2. Volume
Multiply by the depth in feet and divide by 27: 168 × 0.333 ÷ 27 = 2.07 cubic yards.
3. Tons with compaction
Add 15 percent for compaction (2.39 cubic yards) and multiply by 1.50 for crusher run: about 3.6 tons. In 50 lb bags that is roughly 144 bags, so bulk delivery is far cheaper for any gravel pad bigger than a hot tub.
Building a Gravel Pad
- Mark the pad, strip the sod and topsoil, and level the soil.
- Build a frame of pressure-treated 4×4 or 6×6 timbers to hold the gravel in place, and stake it into the ground.
- Lay landscape fabric inside the frame to keep the gravel out of the soil and weeds out of the gravel.
- Spread the gravel in 2 to 3 inch lifts, wet each lift lightly, and compact it with a plate compactor.
- Check level in both directions before the final pass, and screed the top flat.
Gravel Pad Cost
Gravel for a pad costs $25 to $45 per ton in bulk, so a 12 × 14 ft shed pad needs about $110 to $160 of crusher run plus $75 to $150 delivery. Timber framing adds $60 to $150 and fabric $20 to $40. A contractor-built gravel pad typically costs $4 to $8 per square foot including excavation and labor.
Related Gravel Calculators
These tools use the same volume and density maths for neighbouring jobs:
- Shed base gravel calculator — shed foundations in detail
- Gravel base calculator — base depth for patios, slabs and walkways
- Gravel under concrete slab calculator — when the pad will be concrete
- Gravel compaction calculator — how much loose gravel to spread
- Crusher run calculator — the standard pad gravel
- Gravel bags calculator — bag counts for small pads
Densities follow standard quarry ranges for crushed aggregate; the USGS crushed stone statistics publish national production and unit value data.
Gravel Pad FAQ
How much gravel do I need for a 10x12 shed pad?
A 10 by 12 ft shed on a pad that extends 12 inches past each side needs a 12 by 14 ft gravel pad. At 4 inches deep that is about 2.1 cubic yards, or 3.6 tons of crusher run with a 15 percent compaction allowance.
How thick should a gravel pad be?
Use 4 inches of compacted gravel for sheds, hot tubs and AC units, and 6 inches or more for RV and parking pads. Add 2 inches on clay or poorly drained soil.
How much bigger than the shed should a gravel pad be?
Extend the gravel pad about 12 inches past the shed on every side. That keeps roof runoff off the edges and gives the corners solid support.
What is the best gravel for a pad?
Crusher run or 3/4 minus, because the fines compact into a hard, level surface. Clean #57 stone drains better but stays looser, and round pea gravel should be avoided.
How much gravel do I need for an RV pad?
A 12 by 40 ft RV pad with 12 inches of extra gravel on each side, 6 inches deep, needs about 10.9 cubic yards, or roughly 18.8 tons of crusher run with a 15 percent compaction allowance.