Patio Base Calculator
Solid foundations start here. Calculate base material for pavers and concrete.
By Todd Bly, B.S. Construction Management · Updated October 2026
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How to Calculate Patio Base
The Formula
Calculate the 4-6 inch gravel base and 1-inch sand bed separately. Multiply Area x Depth / 27 to get Yards.
Measure Accurately
Measure in feet. For depth, measure in inches and our tool handles the conversion (divide by 12).
Check Your Shape
Most patio base projects are rectangles. If irregular, break it into smaller shapes.
Add Compaction
A patio is only as good as its base. If you skimp on the 6-inch gravel foundation, your expensive pavers will sink and become uneven within 12 months.
The Anatomy of a Perfect Patio
The pavers you see are just the "icing on the cake." The real structural integrity of a patio comes from the 6-9 inches of material underground. Calculating these layers separately is critical for ordering materials.
Patio Cross-Section
Do not skip the fabric layer! It prevents your gravel from disappearing into the mud over time.
Worked Example: Materials for a 12 × 16 ft Paver Patio
Calculate each layer separately, because gravel and sand are ordered and priced differently. The patio area is 12 × 16 = 192 square feet.
- Gravel base, 4 in compacted: 192 × 0.33 = 64 cu ft ÷ 27 = 2.4 cu yd. Add 20% for compaction and order about 2.9 cu yd (roughly 4 tons at ~1.4 tons per yard).
- Bedding sand, 1 in: 192 × 0.083 = 16 cu ft ÷ 27 = 0.6 cu yd. Order 0.75 cu yd in bulk, or about 35 bags of 0.5 cu ft (32 bags plus a little extra).
- Excavation depth: 4 in base + 1 in sand + 2.4 in paver = about 7.5 inches below finished height.
- Soil to remove: 192 × 0.625 = 120 cu ft = 4.4 cu yd in place, about 5.8 cu yd loose once dug.
Extend the base 6–12 inches beyond the paver edge on every side. The edge restraint sits on this extra base, and without it the outer pavers creep outward. For this example the base area becomes closer to 14 × 18 ft, so recalculate with those dimensions before you order.
How Deep Should the Base Be?
| Use | Gravel base (compacted) | Notes |
|---|---|---|
| Walkway or patio, well-drained soil | 4 in | Typical in mild climates |
| Patio on clay or in freeze-thaw areas | 6 in | Extra depth resists frost heave |
| Driveway (cars) | 8–12 in | Use 80 mm driveway-rated pavers |
| Poured concrete slab | 4 in | No sand layer; slab sits on the base |
Check your paver manufacturer's installation guide too, since warranties often specify the base depth.
Getting the Slope and Compaction Right
A patio must shed water away from the house. Build in a fall of 1/8 to 1/4 inch per foot (about 1–2%). On a 16-ft run that is 2–4 inches from the house side to the outer edge. Set this slope in the gravel base, not the sand, so the bedding layer stays an even 1 inch thick.
Compact the gravel in layers no thicker than 2–3 inches, lightly dampened, with a plate compactor, and compact the native soil underneath first. A rented compactor costs far less than relaying sunken pavers. Once the pavers are down, run the compactor over them with a protective pad and sweep in polymeric or joint sand.
Common mistakes
- Ordering gravel by loose volume and running short after compaction.
- Using extra bedding sand to hide an uneven base. Thick sand shifts, so fix the base instead.
- Skipping edge restraint, which lets the outer rows spread.
- Building flat, so water pools against the foundation.
Frequently Asked Questions
How deep for patio base?
For a pedestrian patio, you need 4 inches of compacted gravel base. For a driveway, you need 6-8 inches.
What is 'paver base'?
It is a mix of crushed stone and stone dust (often called Crusher Run or QP) that packs very hard, almost like concrete.
Do I need sand?
Yes, exactly 1 inch of concrete sand (sharp sand) on top of the gravel is needed to level the pavers. Do not use Mason sand (too fine).
How much compaction for patio base?
You must compact the gravel base until it has no give. Using a plate compactor is highly recommended for any patio larger than 10x10.
Can I put pavers on dirt?
No. The ground freezes and thaws, causing pavers to heave. You must have a drainage layer of gravel.
How many yards of gravel for a 20x20 patio?
Area = 400 sq ft. Depth = 4 inches (0.33 ft). Volume = 400 * 0.33 = 132 cubic feet. Divide by 27 = 4.9 Yards. Add 20% for compaction = Order 6 Yards.
What is the difference between sand and stone dust?
Stone dust compacts too hard and traps water, which is bad for the bedding layer (pavers can't settle). Use sand for the final 1-inch layer.
Can I use 'fill dirt' for patio base?
Absolutely not. Fill dirt settles unpredictably. You must use 'processed gravel' or 'road base' that locks together.
