Flagstone Calculator

Estimate the amount of flagstone or natural stone needed for a patio, measured in square feet and tons.

Results

Visualization

How It Works

Flagstone is sold by the square foot or by the ton. This calculator converts your patio dimensions into both measurements so you can compare quotes from suppliers. The weight-per-ton varies with stone thickness.

The Formula

Tons = (Area_sqft x 1.10) / (15 x 1.5 / Thickness)

Variables

  • Area_sqft — Length x Width of patio area in square feet
  • 1.10 — 10% waste factor for irregular stone cuts
  • 15 — Approximate square feet per ton at 1.5 inch thickness
  • Thickness — Stone thickness in inches

Example

A 12 ft x 10 ft patio with 1.5" flagstone: area = 120 sq ft, with waste = 132 sq ft. At 15 sqft/ton, that is 8.8 tons. At $8/sqft, material cost is about $1,056.

Tips

  • Irregular (random) flagstone is cheaper than cut-to-size and gives a natural look.
  • Thicker stone (2"+) is more durable for driveways but 1-1.5" is fine for patios.
  • Dry-laid flagstone on a gravel and sand base allows for easy future repairs.
  • Gaps between flagstones can be filled with polymeric sand, pea gravel, or ground cover plants like thyme.
  • Get a few extra square feet beyond the waste allowance -- natural stone sizes are unpredictable.