How Many Granite Setts Do I Need? A Worked Layout Guide

To estimate granite setts for a rectangular area, count the positions along the length and across the width separately. Use the measured laying face of the sett and the joint agreed for that product. Multiply the two counts, then review cuts and pack sizes before ordering.

Work from the layout, not the pack’s square metres alone

Sketch the paved area inside the edge restraints. Mark steps, drains and any separate border. Take one measurement along each axis of the main rectangle. For a mixed-size pack, work from the supplier’s pattern and piece counts instead of using the single-size calculation below.

For a straight grid with the same joint between each pair of setts, add one joint to the usable run, divide by the sett face plus one joint, and round up. Do this for both axes. Subtract any planned perimeter gaps before calculating the usable run. The result is a count of layout positions. Check where the cuts fall before deciding how many setts to buy.

Worked example for a 3 m by 1.5 m garden area

Take a straight grid of nominal 100 × 100 mm square setts. Assume 10 mm internal joints for this example. The 10 mm is an input for the calculation. Confirm the joint and edge details for the exact product and installation.

Position count for the illustrative square-sett layout
Run Calculation before rounding Positions
Length (3,000 + 10) ÷ (100 + 10) 28
Width (1,500 + 10) ÷ (100 + 10) 14
Whole grid 28 × 14 392

With whole setts, those rows would extend to 3.07 m by 1.53 m. On the 3 m run, putting all the trimming at one end leaves a 30 mm end piece. Dividing the trim evenly leaves two 65 mm end pieces. Across the 1.5 m width, the corresponding edge pieces are 70 mm at one end or 85 mm at both ends. Both options keep the same position count.

These figures illustrate how the choice of starting line affects the cuts. Have your installer check whether the resulting pieces suit the sett and the edge detail. A cut piece may be reusable elsewhere, while breakages, sorting and an offset pattern can change the quantity to order.

To check a row that starts with a whole sett, subtract the full faces already laid and all the internal joints from the usable run. If the result is zero or negative, the proposed last piece would fall inside a joint. For example, a 1,205 mm run with the same 100 mm setts and 10 mm joints needs 12 positions, but 11 whole faces and 11 joints already take 1,210 mm. Keeping ten whole setts between two equal end cuts would leave 47.5 mm of stone at each end. Ask your installer whether those cuts suit the product and edge detail, or whether the border or layout needs adjusting.

Check whether the selling area includes joints

The 100 × 100 × 50 mm Silver Grey sawn and flamed setts provide a useful example. The full-crate option is listed as 800 blocks and 8.00 m². That figure equals the nominal stone faces alone: 800 × 0.10 m × 0.10 m. Compare the 392 layout positions with the piece count of the exact pack you intend to buy, after the cut plan and allowance have been agreed.

Other products can quote area on a jointed basis. For example, Marshalls’ technical notes give different coverage joint assumptions for its own sawn and cropped Granite Eclipse setts. Ask which basis applies to the pack on your shortlist and use the installation instructions for that product.

Choose the right calculation for the job

  • For one row or a border, measure each run and plan the corners. See the straight-border example in the setts and cobbles buying guide.
  • For a mixed-format pack, check the sizes and counts separately. See the worked mixed-pack example.
  • For a curve, diagonal layout or area carrying vehicles, have the layout and product suitability checked for the site before turning an estimate into an order.

Keep the sketch, cut plan and selected pack together when you ask for a project quote.

Guide updated

Compare a 400-block pack with the 392-position layout

The 400-block Silver Grey granite sett pack contains eight more blocks than the layout has positions. Check which cuts can be reused and allow for breakages and sorting before deciding whether this pack is sufficient.

The 4.00 m² pack label matches the nominal stone-face area of 400 blocks. The worked layout measures 4.50 m² overall and includes joints, so compare the piece count and cut plan before ordering.

How many rectangular granite setts make a 3 m border?

For one straight row of nominal 200 × 100 mm setts, turning each block changes both the border width and the number of pieces. This example uses 10 mm between blocks and no joint at either end.

  • 200 mm side along the run. A 100 mm wide row takes 14 full setts and one 60 mm end cut. The 14 full lengths and 14 joints use 2,940 mm, leaving 60 mm of the 3,000 mm run.
  • 100 mm side along the run. A 200 mm wide row takes 27 full setts and one 30 mm end cut. The 27 full lengths and 27 joints use 2,970 mm, leaving 30 mm.

The rows have 15 and 28 positions before allowing for waste and breakages. To avoid the short end cut, the same rows can be centred using two 130 mm end pieces or two 65 mm end pieces respectively. Draw the corners and ends before choosing a pack, then agree the actual dimensions, joints and minimum practical cut with your installer.