Flagstone Calculator
Natural flagstone is sold by weight, not pieces. Get the tons for your patio or path, plus the stone dust and base beneath it.
How flagstone is estimated
tons = area ÷ sq ft per ton × (1 + waste)
Because pieces vary, yards publish a coverage figure per ton for each stone and thickness. Pick the most common thickness in the pile you like. Irregular flagstone needs more waste than cut rectangular stone (10–15% vs 5%), since you’ll trim edges to fit and reject a few cracked pieces.
Typical coverage by thickness
| Thickness | Sq ft per ton | Setting method |
|---|---|---|
| ¾–1 in | 100–120 | Mortar on a concrete slab |
| 1–1½ in | 70–100 | Mortar, or very firm dust bed |
| 1½–2 in | 50–70 | Dry-laid on stone dust |
| 2–3 in | 40–60 | Stepping stones in soil or gravel |
Questions people ask
How much does a ton of flagstone cover?
Roughly 70–100 sq ft for 1–1½-inch-thick patio flagstone, 50–70 sq ft for 1½–2-inch, and 40–60 sq ft for 2–3-inch stepping stones. Thinner stone covers more area but must be set on a mortar bed or very firm base.
How do I calculate flagstone for a patio?
Measure the patio area, divide by the coverage per ton for your stone thickness, then add 10–15% for irregular shapes and cutting. A 200 sq ft patio in 1½–2-inch stone at 60 sq ft per ton needs about 3.3 tons, or 3.7 tons with 10% waste.
What base goes under flagstone?
For a dry-laid patio, 4 inches of compacted crushed base topped with 1–2 inches of stone dust or sand for bedding. Joints are filled with stone dust, polymeric sand made for wide joints, or planted with low ground cover.
Why is flagstone sold by the ton?
Natural flagstone comes in irregular pieces of varying size and thickness, so quarries weigh it on pallets rather than counting pieces. Coverage per ton varies by stone type — dense bluestone covers less than lighter sandstone at the same thickness.