Gravel Base Calculator: How Much Base for Pavers, Sheds & Slabs

Every paver patio, shed foundation, and concrete slab starts with the same thing: a compacted gravel base. Skip it and you'll get settling, cracking, and a project that looks great for six months before it starts falling apart. The base layer is the most important part of any hardscape project — and the math to calculate it is simple.

This guide covers how much gravel base you need for pavers, sheds, patios, and slabs — including the right depth, gravel type, and realistic costs. If you just need a quick number, plug your dimensions into the calculator below.

Gravel Base Calculator

Enter your project dimensions below. Set the depth to match your base requirements (typically 4–6 inches for most projects).

The Formula

Gravel base is calculated like any fill project:

Length (ft) × Width (ft) × Depth (in) ÷ 324 = Cubic Yards

The 324 converts feet and inches into cubic yards in one step (27 cubic feet per yard × 12 inches per foot = 324). Multiply cubic yards by 1.4 to get approximate tons for crushed stone.

How Deep Should a Gravel Base Be?

Base depth depends on what you're building and the soil conditions underneath. Here are the standard recommendations:

Gravel Base for Pavers

Paver projects are the most common reason people need a gravel base calculation. A proper paver base has two layers:

1. Gravel base (4–6 inches): Compacted crushed stone for drainage and structural support
2. Sand bedding (1 inch): Leveling layer for the pavers to sit on

For a 200 sq ft paver patio with a 4-inch gravel base:

200 × 4 ÷ 324 = 2.47 cubic yards of gravel (~3.5 tons)

Plus about 0.62 cubic yards of sand for the bedding layer. For a complete paver material list including paver counts and sand, use our paver calculator.

Gravel Base by Patio Size

Here's how much gravel base you'll need for common patio sizes at 4 inches deep:

Costs assume $35–$65 per cubic yard for crushed stone, which is the typical range for #57 or crusher run from a local quarry or landscape supplier.

Gravel Base for Sheds

A gravel pad is the most popular DIY shed foundation. It's cheaper than concrete, drains well, and doesn't require permits in most areas. The standard approach:

1. Excavate 4–6 inches below grade and extend 12 inches beyond the shed footprint on all sides
2. Install a timber or block border to contain the gravel
3. Fill with crusher run (DGA) and compact in 2-inch lifts
4. Level the top within ¼ inch across the entire pad

For a 10×12 ft shed with a 12-inch overhang and 4-inch base:

12 × 14 × 4 ÷ 324 = 2.07 cubic yards (~2.9 tons)

At 6 inches deep (recommended for larger sheds or soft soil):

12 × 14 × 6 ÷ 324 = 3.11 cubic yards (~4.4 tons)

Shed Base by Size

Gravel Base for Concrete Slabs

Concrete slabs need a gravel sub-base for drainage. Without it, water collects under the slab, freezes in winter, and causes cracking and heaving. The standard is 4 inches of compacted gravel for patios and 6–8 inches for driveways and garage slabs.

For a 20×24 ft garage slab with 6 inches of gravel base:

20 × 24 × 6 ÷ 324 = 8.89 cubic yards (~12.4 tons)

Need to estimate the concrete itself? Use our concrete calculator for the slab portion, and the gravel calculator for the base layer.

Best Gravel Types for Base

Not all gravel works as a structural base. You need angular, crushed stone that compacts tightly and locks together. Avoid round stone like pea gravel or river rock — they shift under load and never form a stable base.

How to Build a Gravel Base

The process is the same whether you're building under pavers, a shed, or a concrete slab:

1. Excavate. Dig to the required depth plus 1–2 inches for compaction. Extend at least 6 inches beyond the project edges.
2. Level the sub-grade. Compact the native soil with a plate compactor. Remove any soft spots and fill with additional gravel if needed.
3. Lay geotextile fabric (recommended on clay or silty soil). This prevents the gravel from sinking into soft ground over time.
4. Add gravel in 2-inch lifts.Spread 2 inches, compact with a plate compactor, repeat until you reach the target depth. Compacting in lifts is critical — dumping the full depth and compacting once won't work.
5. Check grade. Use a long straight edge and level to confirm the surface is flat (or has the required slope for drainage — typically ¼ inch per foot away from structures).

Common Mistakes

• Using pea gravel or river rock:Round stones don't compact or interlock. They shift under weight and create an unstable base. Always use angular crushed stone.
• Skipping compaction:Loose gravel settles unevenly. Rent a plate compactor ($50–$80/day) — it's worth it.
• Not extending the base: The gravel pad should extend 6–12 inches beyond the project edge for stability and drainage.
• Compacting all at once: If your base is 6 inches deep, compact in three 2-inch lifts: not one 6-inch dump.
• Ignoring drainage slope: Water should flow away from structures. Slope the base ¼ inch per foot away from your house or shed.

Related Calculators

Building a patio, shed, or driveway? These calculators handle the other materials you'll need:

• Gravel Calculator — quick cubic yard and tonnage estimates for any gravel project
• Paver Calculator — paver counts, sand, and gravel for patios and walkways
• Sand Calculator — bedding sand for paver projects
• Concrete Calculator — for slabs, footings, and post holes
• Gravel Driveway Guide — depth, cost, and ordering tips for driveways
• Paver Patio Cost Guide — full cost breakdown and planning tips
• Retaining Wall Calculator — block counts and gravel backfill for retaining walls