Stone calculator
Stone Patio Calculator
Everything a stone patio needs, in one pass — surface, base, bedding, joints, edge restraint and the excavated spoil to haul away.
Your project
Four inches over firm soil, six over clay.
For edge restraint. Exclude sides against a house wall.
Surface stone needed
5.12 tons
for 480 sq ft of patio
- Base gravel
- 12.96 tons (7.11 cu yd)
- Bedding sand (1")
- 1.48 cu yd
- Polymeric joint sand
- 7 bags
- Edge restraint
- 60 lf + 90 spikes
- Spoil to remove
- 12.04 cu yd loose
- Surface stone cost
- $3,840
- Installed cost range
- $7,200 – $16,800
Slope the finished surface away from the house at 1/4 inch per foot — 2 inches of fall over an 8 foot patio. Level patios against a foundation cause the water problems people blame on the patio material.
The shareable link reopens this calculator with your exact inputs.
The patio section, top to bottom
Surface stone, 1 inch of coarse bedding sand, 4-6 inches of compacted dense-graded base, and firm subgrade with geotextile if it is soft. That is the entire assembly, and the base is the part that determines whether it is flat in ten years.
Excavate the total: stone thickness + 1 inch bedding + base depth. For 1.5 inch flagstone on a 4 inch base that is 6.5 inches, plus a bit for the slope. Excavated soil swells about 25% loose, so plan disposal at 1.25× the dug volume.
What drives the cost
Installed stone patios run $15 – $35 per square foot. Dry-laid flagstone on a proper base sits mid-range; mortared stone over a concrete slab is $30-$60 because you are paying for two structures.
The base is roughly 20% of the material cost and 100% of the longevity. Cutting the base from 4 inches to 2 saves a few hundred dollars and guarantees settlement.
Materials per 100 sq ft of patio
| Item | Quantity |
|---|---|
| Base gravel (4" compacted) | 2.0 tons |
| Bedding sand (1") | 0.31 cu yd / 0.42 tons |
| Flagstone (1.5") | 0.97 tons |
| Polymeric joint sand | 1-2 bags |
| Excavated spoil | 2.4 cu yd loose |
Frequently asked questions
+How much base do I need under a stone patio?
Four inches of compacted dense-graded base over firm soil, six inches over clay, plus one inch of coarse bedding sand. Order 20% extra to allow for compaction.
+How much does a stone patio cost?
$15-$35 per square foot installed for dry-laid stone, $30-$60 for mortared stone over a concrete slab. DIY material cost alone is $6-$15 per square foot.
+How deep do I excavate for a patio?
Stone thickness plus 1 inch of bedding plus the base depth — typically 6.5 to 8.5 inches total for a dry-laid patio.
+What slope does a patio need?
1/4 inch of fall per foot, running away from any structure. That is 2 inches over 8 feet, which is barely perceptible underfoot but sheds water reliably.