Flagstone Calculator
Calculate tons of flagstone needed for patios, paths, and stepping stones
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Tips & Notes
- •At 1.5" thickness, one ton of flagstone covers approximately 80–100 sq ft.
- •Natural flagstone (bluestone, slate, limestone, sandstone) varies widely in density.
- •Order 15–20% extra for irregular shapes — cuts and waste are higher than pavers.
- •Set in mortar on a concrete base for permanent installations; dry-laid in sand for flexible paths.
- •Thickness affects load capacity: 1"–1.5" for foot traffic, 2"+ for vehicle areas.
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Pro tips for flagstone
- ›At 1.5" thickness, one ton of flagstone covers approximately 80–100 sq ft.
- ›Natural flagstone (bluestone, slate, limestone, sandstone) varies widely in density.
- ›Order 15–20% extra for irregular shapes — cuts and waste are higher than pavers.
- ›Set in mortar on a concrete base for permanent installations; dry-laid in sand for flexible paths.
- ›Thickness affects load capacity: 1"–1.5" for foot traffic, 2"+ for vehicle areas.
Frequently asked questions
How much flagstone do I need for a 200 sq ft patio?▾
At 1.5" thickness, one ton of flagstone covers 80–100 sq ft. A 200 sq ft patio needs 2–2.5 tons. Order 15–20% extra (so 2.5–3 tons) — flagstone has irregular shapes that produce more waste than uniform pavers.
Dry-laid vs. mortared flagstone — which should I choose?▾
Dry-laid flagstone (sand base) is faster, cheaper, and easier to repair but shifts over time. Mortared flagstone (concrete base + mortar joints) is permanent and rigid but cracks if the slab moves. Use dry-laid for paths and informal patios; mortared for formal areas.
What's the difference between bluestone, slate, and sandstone flagstone?▾
Bluestone (Pennsylvania bluestone) is dense and uniform blue-gray — most durable. Slate is layered and splits naturally — risk of flaking in freeze/thaw. Sandstone is porous and warm-colored — needs sealing in cold climates. Limestone is softer and less weather-resistant.
How much does flagstone cost?▾
Flagstone runs $200–$500/ton delivered depending on stone type. Pennsylvania bluestone: $300–$450/ton. Tennessee crab orchard: $250–$400/ton. Installed (dry-laid): $15–$30/sq ft. Installed mortared on concrete: $25–$50/sq ft.
How thick should flagstone be?▾
1"–1.5" for foot traffic on a compacted base. 1.5"–2" for set-in-mortar applications. 2"+ for driveways or areas with vehicle traffic. Thicker stones are easier to set level but harder to handle — 1.5" is the sweet spot for most patios.