Guides · Materials
How much does a stone top weigh, and what has to carry it
In short. A square metre of 30 mm marble weighs about 81 kg, and a 240 × 100 cm top comes to almost 200. The figures alarm people more than they should: the floor of an ordinary home carries them with room to spare, while the real constraints are three others — the base, the stairwell and the front door. Here are the calculations, the standards, and the points where you genuinely have to stop.
How much does a square metre of stone weigh?
One step: density times thickness. Density is the figure to ask your supplier for — it is measured as apparent density to EN 1936 and it differs from stone to stone. As a working figure, marbles and quartzites sit almost always between 2,600 and 2,850 kg/m³; Table A.2 of EN 1991-1-1 gives granites at 27.0-30.0 kN/m³, roughly 2,750-3,050 kg/m³.
At 2,700 kg/m³, a reasonable average for a marble, the arithmetic comes out like this.
| Thickness | Weight per square metre |
|---|---|
| 20 mm | about 54 kg |
| 30 mm | about 81 kg |
| 40 mm | about 108 kg |
| 60 mm (or 30 mm with a doubled visible edge) | about 162 kg over the solid part |
Every figure below holds to ±5%: a denser stone pushes them up, a travertine brings them down.
And a whole table?
Multiply the area by the weight per square metre. A few real cases.
| Piece | Area | Weight of the top alone |
|---|---|---|
| Coffee table 120 × 60, 20 mm | 0.72 m² | about 39 kg |
| Round table Ø 140, 30 mm | 1.54 m² | about 125 kg |
| Table 240 × 100, 30 mm | 2.40 m² | about 194 kg |
| Table 300 × 110, 30 mm | 3.30 m² | about 267 kg |
| Full slab 320 × 180, 20 mm | 5.76 m² | about 311 kg |
The last line always surprises people: the raw slab weighs more than the table cut from it. That is why slabs move on suction lifters and A-frames rather than by hand, and why a piece is cut as late as possible.
To the top you add the base: a steel base for a 240 cm table runs around 30-50 kg, a solid stone base can weigh as much as the top. A large stone table usually totals between 230 and 400 kg.
Will the floor take it?
Almost always yes, and it can be checked against the standards rather than guessed at.
Eurocode EN 1991-1-1, Table 6.2, gives Category A — domestic and residential activities — a recommended uniformly distributed load of 2.0 kN/m² on floors, with the national annex fixing the final value; in Italy the code sets exactly 2.00 kN/m², a little over 200 kg per square metre, for a category that expressly includes hotel bedrooms. For areas with tables — schools, cafés, restaurants, Category C1 — the figure rises to 3.0 kN/m².
Now the sum. A 240 × 100 cm table with a 30 mm top and a steel base weighs around 240 kg and stands on 2.4 m²: about 100 kg per square metre, half what the floor was designed for — and that design figure assumes a room full of people, not one stationary table.
Then there is the concentrated load check, which is what worries anyone thinking about the foot of a pedestal. For Category A the Italian code applies 2.00 kN over a square contact area of 50 × 50 mm where nothing more precise is specified: that is 800 kN per square metre at that point, against the 82 applied by a 120 × 120 mm base foot carrying 120 kg. The check the standard imposes on the floor is nearly ten times more severe than your table's foot.
When do you have to stop and ask?
In four cases, and they are specific.
Historic floors. A timber floor, or one of steel joists and brick vaults, was not designed to these figures: the answer comes from an engineer who looks at it, not from a table.
Weight concentrated on little bearing. A table spreads its load well; a sculpture or a solid block on a narrow base does not. What counts is the ratio of weight to bearing area.
Underfloor heating screeds and floating floors. Here the structure is not in question, the finish is: a thin screed with pipes in it, or a floating timber floor, can give locally under a heavily loaded foot. The fix is a wider bearing.
The delivery itself. The worst moment is not the finished table: it is the crate resting for a few minutes on two points in the middle of a corridor.
What does the base have to withstand?
Stiffness rather than load. Stone has no tolerance for flexing: if the structure beneath moves, the top does not bend, it breaks. A frame that carries a timber top may not carry the same top in stone, because timber goes along with the movement and stone does not.
Two practical rules. The top must be supported continuously along its length, not only at the ends; and the overhang has a limit set by thickness and by flexural strength to EN 12372 — the numbers are in how thick a marble top should be. And the top should not be bonded rigidly to the frame: it sits on resilient supports, because stone and metal expand differently.
Getting it into the house: stairs, lifts, doors
This is the question nobody asks in time, and the limit is almost never the weight — it is the dimension.
A lift's rated load is on the plate inside the car, to be compared with the heaviest single piece plus two people. But first compare the length of the piece with the diagonal of the car, because that is usually where the top fails: a 240 cm top will not go into an ordinary residential lift whatever its rated load. On stairs the measurement that counts is the landing, not the flight, because a slab always travels on edge and needs room to turn.
Weight decides how many people are needed. Annex XXXIII of Italian Legislative Decree 81/2008 refers to the ISO 11228 series and lists «the load is too heavy» among the risk factors without setting any limit in kilograms: grip and posture weigh too, and a slab is the worst case on both. This is why a 200 kg top is not four people carrying 50 kg each: it moves with equipment, and above all it is designed so that it fits — split in two with a joint planned along the veining, with a base that comes apart, or at 20 mm with a 40 mm visible edge.
Can a slab be made lighter?
In three ways. Reduce the thickness: going from 30 to 20 mm removes a third of the weight where the free span allows, often paired with a bonded edge that gives back the visual thickness. Bond the stone to a honeycomb panel: a thin slab backed this way weighs a fraction of solid stone, and it is the route where weight is a genuine constraint, on board a boat or on a suspended wall; it has to be engineered, not improvised. Choose a less dense stone: a travertine weighs less than a granite, but porosity, water absorption to EN 13755 and behaviour with stains change with it.
The opposite is worth saying too: in a table, weight is a quality. A stone top does not shift when you lean on it, does not vibrate, and needs no fixing down.
How we work
Stoneform makes tables, tops and works in marble, onyx and natural stone. We buy blocks directly at the quarry and saw the slabs ourselves, in our own factory. When a stone is not available to us as a block, we buy the slabs from importers we trust. Before cutting, every slab is examined against the light, to see how it is made inside before deciding where the cut falls. We do not use resin to reinforce slabs; on large surfaces a support helps, and the mesh on the back is already a good support in itself.
On price, in two lines: retailers apply a mark-up of 35-50% on the maker's price, buying from someone who imports the stone directly saves a further 20% or so, and a 240 cm marble table costs around 3,800 euro. Orders of magnitude, not a price list; the detail is in how much a custom marble table costs.
Our pieces are in the tables collection and among our works; the Contract page explains how we handle commissions, and in hotels the calendar matters most, as set out in when to order hotel furniture to open on time. Stoneform and Brianform are two divisions of the same company: start from a drawing or an idea and write to us.
Frequently asked questions
How much does a square metre of 20 mm marble weigh?
About 54 kg at a density of 2,700 kg/m³; at 30 mm it is about 81 kg. Ask the supplier for the exact figure as apparent density to EN 1936.
Will a 240 cm marble table damage the floor?
The complete table weighs around 240 kg; over the area it occupies that is roughly 100 kg per square metre, against the 200 a residential floor is designed for. Only historic floors need checking.
How many people does it take to move a stone top?
It is not solved by dividing the kilos: a slab is wide, rigid and hard to grip, and it always travels on edge. Past a hundred kilos or so you use equipment.
Will a stone top go in a lift?
The limit is almost always dimension: the length of the top against the diagonal of the car first, then the weight against the rated load on the plate. A 240 cm top generally will not go.
Can a lighter top be made?
Yes: reduced thickness, a thin slab on a honeycomb panel, or a less dense stone. Each of the three changes something else.
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The standards cited are the Italian NTC 2018 (Table 3.1.II and § 3.1.4.2) for imposed and concentrated loads, EN 1991-1-1 (Table 6.2 and Table A.2) for European imposed loads and stone unit weights, EN 1936 for apparent density, EN 12372 for flexural strength, EN 13755 for water absorption, and Annex XXXIII of Italian Legislative Decree 81/2008, which refers to the ISO 11228 series for manual handling without setting any limit in kilograms. The 2,700 kg/m³ used in the calculations is a working figure and not a code value: EN 1991-1-1 does not list marble, and real stones fall between about 2,600 and 2,850 kg/m³. All weights given are therefore estimates to ±5% and not measurements; the density of a given slab should be requested from the supplier. The prices quoted are orders of magnitude and do not constitute a quotation. Checking an existing floor structure is a job for a qualified engineer.