Paver Base 101: Sand and Gravel You Actually Need

Updated 2026-07-30 · Yardly

A paver patio needs two layers under the pavers, and they are not interchangeable: a compacted crushed-stone base of at least 4 inches, and exactly 1 inch of coarse bedding sand on top. For every 100 square feet, that works out to roughly 1.5 cubic yards of gravel ordered and about 0.31 cubic yards of sand. Here’s what each layer does, and the math for both.

Two layers, two different jobs

It’s tempting to treat “base” as one generic pile of material, but the system only works because the layers divide the labor:

• The gravel base carries the load. Dense-graded crushed stone — sold as road base, crusher run, or Class II base — locks into a nearly rigid platform when compacted. It spreads foot traffic over the subgrade, drains water, and resists frost heave.
• The sand bed levels the surface. Pavers vary slightly in thickness; a thin cushion of coarse sand lets each one seat flush with its neighbors. When you run the plate compactor over the finished surface, sand migrates up into the joints and starts the interlock that keeps pavers from creeping sideways.

Mix the jobs up — pavers straight on gravel, or a thick sand bed doing structural duty — and you get rocking, sinking, and joint lines that wander within a season.

The gravel layer: 4 inches compacted, ordered with a margin

The Interlocking Concrete Pavement Institute specifies a minimum 4-inch compacted aggregate base for pedestrian patios and walkways, stepping up to 6 inches or more over clay soils or in freeze-thaw climates, and 8–12 inches for driveways.

The volume math is the standard Yardly formula:

(Length × Width × Depth in inches ÷ 12) ÷ 27 = cubic yards

Two adjustments before you order:

1. Extend the footprint 6 inches past the paver edge on every open side — the base must be wider than the surface it supports.
2. Add a compaction margin. Crushed stone loses 15–20% of its loose volume under the compactor, so multiply the compacted volume by about 1.2.

For a 12×12 patio: the footprint becomes 13×13 ft = 169 sq ft. At 4 inches: 169 × 0.333 ÷ 27 ≈ 2.08 yd³ compacted → order about 2.2–2.5 cubic yards. The gravel calculator runs this in one pass and converts to tons (crushed stone runs about 1.4 tons per yard).

The sand layer: 1 inch, and no more

Bedding sand is the layer people over-think and then over-pour. The standard is strict: 1 inch compacted, screeded at about 1.25 inches loose. Deeper sand doesn’t add cushion — it adds instability, because an unconfined sand layer behaves like a fluid. Pavers pressed into a 2–3 inch bed settle at different rates, pump sand up through the joints under load, and hold water against the paver bottoms.

Use washed concrete sand (ASTM C33) — coarse, angular grains that lock under compaction and drain freely. Skip play sand, masonry sand, and stone dust; their fine particles hold water and wash out.

The quantity math is easy because the depth is fixed:

Square feet × 0.0031 ≈ cubic yards of bedding sand

That’s the volume formula with 1 inch baked in. A 12×12 patio (144 sq ft) needs about 0.45 cubic yards — order a half yard. The sand calculator handles odd shapes and unit switches.

Order of operations on install day

1. Excavate deep enough for the whole stack: paver thickness + 1 inch of sand + 4–6 inches of base.
2. Compact the subgrade, then spread and compact the gravel in 2–4 inch lifts — never the full depth in one pass.
3. Set 1-inch screed rails on the compacted base, spread sand, and pull a straightedge across the rails. Don’t walk on the screeded bed.
4. Lay pavers, counted with the paver calculator, then compact and sweep joint sand.

Keep reading

• The paver patio project estimator totals gravel, sand, and pavers from one set of dimensions.
• How much gravel for a patio base goes deeper on stone selection and lift compaction.
• How to estimate pavers for a patio covers the surface layer — counts, patterns, and waste factors.

Frequently asked questions