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Flagstone Calculator

Enter your patio size to see how many tons of flagstone to order, plus base gravel, bedding sand, weight, pallets, and a stone-only cost.

How much flagstone do I need? Add a waste allowance to the patio area, then divide by the coverage per ton. A ton of 1.5-inch flagstone typically covers 90–110 sq ft; 2.5-inch covers about 70 sq ft. A 12x12 patio (144 sq ft) with 10% extra needs about 1.4–1.8 tons of 1.5-inch stone.
Materials Flagstone Cost Estimate

Enter Your Measurements

Hardscape Genius

Your estimate is only step one.

The calculator tells you how much to order. Hardscape Genius helps you decide where each irregular stone should go after delivery, before the crew starts dragging pieces back and forth from the pallet.

  • AI reads exact measurements from photos
  • Drag-and-drop layout on phone or tablet
  • Works during lunch break after delivery

Try it on a real job

Best fit: you have stone arriving soon, a photo of irregular pieces, or a crew that needs a clear layout plan before installation starts.

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No card required. The trial begins after your first successful stone processing.

How This Calculator Works

  1. 1 Enter area directly, use length by width, or enter a round patio diameter
  2. 2 Choose the stone, then replace the starting coverage with supplier data
  3. 3 Adjust thickness, waste, pallet weight, price, base, and sand assumptions
  4. 4 Get instant estimates for all three material layers

Ordering Tips

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Waste is editable. Set an allowance for cuts, breakage, package rounding, and useful spare pieces.

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Compaction assumption. Gravel and sand results use a disclosed 30% loose-material allowance. Confirm it with the supplier.

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Verify with supplier. Always confirm quantities with your local stone yard before ordering.

Your project, routed by what happens next

Where are you in the patio project?

Choose the closest stage. The article and calculators stay completely free and available.

01 I’m choosing a material

Compare cost, upkeep, climate fit, and appearance before you commit.

Compare flagstone, bluestone, and pavers Email me the free decision report
02 I need to know how much to order

Calculate stone, base gravel, and bedding sand without giving up your contact details.

Calculate my material order Check a stone waste allowance
03 My stones are delivered

Use one non-renewing Project Pass for this DIY job, or begin in the no-card planner.

Choose the DIY Project Pass Use the no-card planner instead
04 I want someone to plan or install it

Have an experienced stonemason design the layout for your actual stones, or use the field guide with an installer you choose.

See the Patio Design Service Use the DIY layout guide

How Much Flagstone Do I Need for Common Patio Sizes?

Tons to order with a 10% allowance for cuts and breakage. Thin stone covers more ground per ton than thick stone, so check the thickness your supplier quotes.

Tons of flagstone to order by patio size and stone thickness
Patio size Area 1.5 in. flagstone (90–110 sq ft/ton) 2.5 in. flagstone (70 sq ft/ton)
10x10 100 sq ft 1.0–1.2 tons 1.6 tons
10x12 120 sq ft 1.2–1.5 tons 1.9 tons
12x12 144 sq ft 1.4–1.8 tons 2.3 tons
12x16 192 sq ft 1.9–2.3 tons 3.0 tons
14x14 196 sq ft 2.0–2.4 tons 3.1 tons
16x16 256 sq ft 2.6–3.1 tons 4.0 tons
16x20 320 sq ft 3.2–3.9 tons 5.0 tons
20x20 400 sq ft 4.0–4.9 tons 6.3 tons
20x24 480 sq ft 4.8–5.9 tons 7.5 tons
24x24 576 sq ft 5.8–7.0 tons 9.1 tons

Coverage figures from the Pine Landscape Center 2026 retail price guide. Your supplier's coverage for the exact product controls the order.

How to Calculate Flagstone for a Patio

  1. Measure the area. Length × width for rectangles. Split L-shapes and curves into simple shapes and add them up.
  2. Add a waste allowance. 10–15% covers cuts, broken pieces, and stones that don't fit. More edges and curves mean more waste.
  3. Divide by coverage per ton. Ask the supplier how many square feet a ton covers at the thickness you're buying.
  4. Round up to how the stone is sold. Many yards sell by the pallet or half ton. The calculator shows pallets using your pallet weight.

Price per Ton vs Price per Square Foot

Thicker flagstone often costs less per ton but more per square foot, because a ton covers less ground. In one 2026 supplier price list, 2.5-inch stone was $37 per ton cheaper than 1.5-inch stone, yet about $1–$2 more per square foot of patio. Enter the price per ton in the calculator above to see your stone cost, or read the flagstone cost guide for price ranges by stone type.

After the Stone Arrives: Plan Before You Lift

The calculator tells you how much flagstone to order. It can't tell you where each irregular piece goes. That decision is where most of the labor and waste happens: stones carried to the patio, tried, rejected, and cut to fill gaps.

Once your flagstone is delivered, lay the pieces out and photograph them. Hardscape Genius measures every stone from the photo so you can arrange the patio on your phone, plan only the cuts you need, and hand the crew a numbered map.

See how the layout planner works Calculate gravel and sand for other stone

Frequently Asked Questions

How much flagstone do I need for a patio?

Add a waste allowance to the patio area, then divide by the stone's coverage per ton. A 12x12 patio (144 sq ft) with a 10% allowance needs about 1.4-1.8 tons of 1.5-inch flagstone at 90-110 square feet per ton.

How many square feet does a ton of flagstone cover?

It depends on thickness. One 2026 supplier price list shows 90-110 square feet per ton for 1.5-inch flagstone and about 70 square feet per ton for 2.5-inch flagstone. The calculator defaults to 100 square feet per ton; enter your supplier's figure for the exact product.

How much flagstone do I need for a 10x10 patio?

A 10x10 patio is 100 square feet. With a 10% allowance, plan about 1.0-1.2 tons of 1.5-inch flagstone, or about 1.6 tons of 2.5-inch flagstone.

How much does a ton of flagstone cost?

HomeAdvisor's June 2026 data lists sandstone at $200-$350 per ton, limestone at $250-$400, bluestone at $375-$450, quartzite at $400-$450, and slate at $475-$700. Local suppliers and grades vary.

How much gravel do I need under flagstone?

For a 4-inch compacted base, multiply the area by 4, divide by 12 for cubic feet, add 30% for compaction, and divide by 27 for cubic yards. A 100 sq ft patio needs about 1.6 cubic yards of base gravel.

How much extra flagstone should I order?

Plan 10-15% extra for cuts, breakage, and pieces that don't fit. Irregular stone and patios with many curves or edges use more. Confirm the allowance with your supplier and installer.

Calculate Materials by Patio Size

Planning a specific patio size? Jump directly to pre-filled calculators for common dimensions:

Round Patio Calculator

Planning a circular patio or fire pit area? Calculate materials using: Area = π × (diameter ÷ 2)²