Granite Setts per Square Meter: Why One Answer Says 100 and Another Says 83
Granite setts per square meter is not a fixed figure. A 100×100 mm sett with no joint gives 100 pieces per square metre; the same sett on a 10 mm joint gives 83. On one and the same paved area, ordering 100 pieces or 83 pieces is a 17% difference in count, not in area. Face size, joint width and laying pattern decide the number, so fix the joint first.
How many granite setts are there per square meter, and why do some say 100 while others say 83?
The count is not one fixed number; it comes out of three variables: face size, joint width and laying pattern. Butt-jointed, a 100×100 mm sett gives 1,000,000 ÷ 10,000 = 100 pieces and a 200×100 mm sett gives 50; on a 10 mm joint the same faces give 1,000,000 ÷ (110×110) ≈ 83 pieces and 43. The formula: setts per square metre = 1,000,000 ÷ [(face length mm + joint mm) × (face width mm + joint mm)]. Quoting the same area at 100 pieces assumes butt-jointed paving; quoting it at 83 assumes a 10 mm joint. The area is the same and the stone is 17% different — what changes is not the area but whether the joint is counted into the piece count. Stone weight per square meter = pieces in that row × weight per piece: 83 × 2.7 = 224 kg, 43 × 5.4 = 232 kg. With a 10 mm joint a paved square meter holds only 83 setts and the rest is jointing sand, which is not stone. On 100×100 the jointed square meter is 46 kg lighter; on 200×100 it is 38 kg lighter (270 − 232 = 38). The count is rounded to whole setts and is for estimating only; order by area, not by multiplying the count.
| Size (mm) | Setts per m² | Stone weight per m² |
|---|---|---|
| 100×100×100, no joint | 100 | 270 kg |
| 100×100×100, 10 mm joint | 83 | 224 kg |
| 200×100×100, no joint | 50 | 270 kg |
| 200×100×100, 10 mm joint | 43 | 232 kg |
How wide should the joint be, and why is that not the factory's decision?
Joint width comes from the setting-out drawing and the laying pattern. A factory can only count setts against the joint width you give it; it cannot choose that width for you. In straight laying the joint is constant row after row and the formula above holds. In fan or radial laying it does not: the outer arc is longer than the inner one, the setts open up, the joint widens towards the outside, and a square meter holds fewer pieces than the same stone laid straight. Boundaries, corners and rings around tree pits shift the joint again, which is why changing the pattern changes the count. There is one action: send the setting-out drawing to the supplier, marked with the pattern, the joint width and the starting point, and ask for the count and the cutting layout against that drawing. Without it, the supplier estimates on a default joint and the number will not match site.
What does the count per square meter have to do with the tonnes in a container?
A 100×100×100 mm sett is 0.001 m³, so 2.7 kg, and 100 of them butt-jointed make 270 kg per m². A 200×100×100 mm sett is 5.4 kg, and 50 of them also make 270 kg per square meter. A 100×100×50 mm sett is 1.35 kg, and 100 of them make 135 kg per square meter. At a fixed thickness, stone weight per square meter is set by thickness and by the area the joints take: 270 kg with no joint, 224 kg on a 10 mm joint. So 100 versus 83 differs not only in count and appearance but by 17% of stone tonnage — on 1,000 m², a 10 mm joint means 46 tonnes less granite and that much more sand.
| Size (mm) | Weight per sett | Setts per m² | Stone weight per m² (no joint) |
|---|---|---|---|
| 100×100×100 | 2.7 kg | 100 | 270 kg |
| 200×100×100 | 5.4 kg | 50 | 270 kg |
| 100×100×50 | 1.35 kg | 100 | 135 kg |
How many square meters fit in a container, and why can't 346 m² be applied to setts?
It cannot. 346 m² is the flat-stow ceiling we record for 30 mm slabs in a 20 ft container, which works out to 346 × 0.03 × 2.7 ≈ 28 tonnes. That is a weight figure. Put the same 28 tonnes into 100 mm setts: 28 ÷ (0.1 × 2.7) = 28 ÷ 0.27 ≈ 104 m², roughly a third of the 346. That 104 m² assumes butt-jointed paving at 270 kg per m², so it is the conservative figure. On a 10 mm joint at 224 kg per m², the same 28 tonnes covers about 125 m². So 346 is a ruler for 30 mm slabs, not a quantity for setts. Sizing your own container takes two steps: ask the carrier for the weight limit of that container type on your route, then divide it by (thickness m × 2.7). If the result is smaller than your volumetric estimate, quote the smaller one.
How much waste should I add, and how do I lay it out myself?
Waste is not a fixed percentage; it grows out of the layout. Curves need cutting, corners need chamfers, edges need closing, broken runs need filling, and everything cut off never reaches the paved face. So draw the layout first, then set the rate, not the other way round. The formula: order area = net paved area ÷ (1 − agreed waste rate). Conditional example: if the layout works out at 5% waste, order net area ÷ 0.95, which is 105.3 m² for 100 m² net; at 8%, divide by 0.92. Doing it yourself is not hard: print the drawing, set a grid at 1:20, one cell per sett, count the halves on the boundary separately, then divide cut pieces by the total to get the rate for that version. Half an hour with a pencil beats a stack of stone that fits nowhere in the container.
Which four items must be fixed in writing on the enquiry?
Four items, and quotes become comparable and delivery arguable on facts rather than memory. Fill these in before you discuss price. At Guangxi Shicai Stone Industry Co., Ltd., Sesame Black G654 in standard slabs ships in 5 days, the minimum order is 100 m², and we run our own quarry, 20 large saws and 500,000 m² a year; setts are cut to size against your layout, and their lead time is quoted separately from the slab lead time, with the count and the waste figure returned with the quote.
| Item | How to write it | What goes wrong if you don't ask |
|---|---|---|
| Face size and thickness tolerance | Face size, thickness and permitted deviation, signed by both sides | A thin delivery still settles by area, so you pay for stone that is not there |
| Whose drawing sets the joint | The buyer's setting-out drawing governs, with pattern and joint width marked | The factory assumes a default joint, site joints do not line up, and edges run out of material |
| Which area figure is quoted | Net paved area, cutting area or packing-list area, and which one settles | Three figures for one batch invite a dispute over the gap |
| Count or area as the settlement basis | By count: pieces and face size. By area: which area | Priced at 100 pieces, settled at 83, two bases on one sheet |
Related reading