Flagstone calculator
Flagstone calculator: how much flagstone do you need?
Flagstone is sold by the ton, and how far a ton goes depends on the stone and its thickness, so start from your supplier’s coverage: tons = (area + extra for fitting) ÷ square feet per ton. If your stone covers 100 square feet per ton, a 16 by 12 foot patio with 10% extra needs 2.11 tons. Enter your patio and your supplier’s figures below for tons, pallets, the setting bed and the cost per square foot.
Your patio or path
Your supplier’s figures
Setting bed
192 sq ft. Enter your supplier’s coverage per ton (or weight per square foot) to see the tons.
How to estimate flagstone
- Measure the area. Length times width; split curves and odd shapes into rectangles and circles.
- Add extra for fitting. Irregular stone is cut to fit, so some of every piece is lost.
- Ask your supplier for the coverage. Square feet per ton for the stone and thickness you are buying (or pounds per square foot: coverage = 2,000 ÷ pounds).
- Divide. Square feet ÷ coverage per ton = tons.
- Add the setting bed and price it. Bed volume from its depth; cost per ton and per square foot.
More for the job: the gravel calculator for base stone, the sand calculator for a sand bed, and the paver calculator to compare a paver patio.
Frequently asked questions
- How do I calculate how much flagstone I need?
- Work out the area in square feet, add extra for cutting and fitting the irregular pieces, then divide by your supplier's coverage per ton. If the stone you are buying covers 100 square feet per ton, a 16 by 12 foot patio (192 square feet) with 10% extra needs 211.2 ÷ 100 = 2.11 tons.
- How much area does a ton of flagstone cover?
- It depends on the type of stone and how thick it is: thin stone covers more area per ton than thick stone. Your supplier knows the coverage of the stone they sell, usually in square feet per ton; that is the number to order by.
- How do I convert flagstone weight per square foot to coverage per ton?
- A ton is 2,000 pounds, so coverage per ton = 2,000 ÷ the pounds per square foot. Stone that weighs 20 pounds per square foot covers 2,000 ÷ 20 = 100 square feet per ton.
- How much does a flagstone patio cost?
- Multiply the tons by your supplier's price per ton and add the setting bed, delivery and any labor. The calculator does the stone and bed at your prices and gives the cost per square foot, the number most quotes are compared on.
- How much is 100 square feet of flagstone?
- 100 square feet ÷ your supplier's coverage per ton gives the tons; multiply by their price per ton. Enter 100 as the area and your supplier's figures and the calculator shows it, with extra for fitting.
- How much extra flagstone should I order?
- Irregular stone has to be cut and fitted, so some of each piece is lost; most people order extra. Thicker stone and tight, regular joints waste more. The calculator adds the percentage you choose.
- What do I set flagstone on?
- That depends on the stone, the site and whether it is dry-laid or mortared, so follow your supplier's or contractor's guidance. Enter the setting bed depth they give and the calculator works out the cubic yards.
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