How Much Flagstone Do I Need?
Flagstone is sold by the ton, and how far a ton goes depends entirely on how thick the stone is. That catches people who have priced a patio by the square foot.
The rule: a ton covers roughly 200 square feet divided by the thickness in inches.
| Thickness | One ton covers | Typical use |
|---|---|---|
| 1 in | ~200 sq ft | Patios set on sand, light foot traffic |
| 1½ in | ~133 sq ft | The usual choice for a patio or path |
| 2 in | ~100 sq ft | Driveways, heavy traffic, stepping stones |
| 2½ in | ~80 sq ft | Steps, treads, dry-laid on soil |
So a 12 by 14 ft patio — 168 square feet — in 1½ inch flagstone needs about 1.3 tons.
Add 10–15% for cuts and breakage
More than you would for a rectangular material, because flagstone is irregular by nature:
- Straight-edged patio, tight joints — add 10%
- Curved edges or a random pattern — add 15%
- Stepping stones — add 10%, and expect to reject some pieces on shape alone
Running short is worse here than with a uniform material. Flagstone is quarried in batches and colour varies between them, so stone bought a month later may visibly not match.
Thickness decides more than coverage
It also decides how the patio is built:
- Under 1½ in needs a mortar bed over concrete. Laid on sand it will crack under load.
- 1½ to 2 in can be dry-laid on a compacted base with bedding sand — the same build as pavers. See what goes under pavers.
- Over 2 in is heavy enough to set straight onto a well-prepared base, and is what you want for stepping stones in a lawn.
Thicker stone costs more per ton and covers less, so the price per square foot rises steeply. It is usually cheaper to build a proper base under thinner stone than to buy thickness to compensate for a poor one.
Irregular or cut
Irregular — natural broken edges, fitted like a jigsaw with wider joints. Cheaper per ton, more labour, and more waste.
Cut or "pattern" — sawn to rectangles in set sizes. More per ton, far faster to lay, less waste, and the only sensible option for a formal layout.
For a first patio, cut stone is usually the better value once your own time counts for anything.
What else the job needs
Budget for the layers underneath as well as the stone. A dry-laid 1½ inch patio at 168 square feet also wants roughly 3–4 tons of crusher run for the base and half a ton of concrete sand for bedding — several times the tonnage of the flagstone itself, and often overlooked when pricing the job.
Ask any yard three things: price per ton, the thickness they are quoting, and whether it is irregular or cut. Find flagstone and natural stone suppliers near you on Topsoil.com.