Renovation Cost per Square Metre: Estimate from a Plan

A renovation cost per square metre is a useful first number, and a poor final one. Two flats of the same size can differ by double, because one needs a new bathroom and the other only paint. The way to a number you can trust is the way estimators work: take the quantities off the floor plan room by room, then price each line. This guide shows you how to do that with the plan from a listing or a developer, and gives dated 2026 price ranges to check your total against.

What the floor plan can and can’t tell you

The plan gives you most of the quantities a renovation is priced on:

Floor area of each room, and so of each floor finish.
Wall lengths, which with the ceiling height give wall area.
Doors and windows: how many, how wide, and where they cut into walls and skirting.
Wet rooms and the kitchen: where tiles, pipes and extraction go.
Items to count: interior doors from their swing arcs, sanitary fittings, radiators, and sockets and lights if there is an electrical drawing.

It can’t tell you what is behind the surface: how flat the walls and screed are, how old the wiring is, whether the pipes are sound. That is what the contingency at the end is for.

Before you measure anything, check the plan’s scale. Use the room areas and dimension lines written on it, not a ruler on your screen. If you are unsure how, read how to read a floor plan and how to measure floor area first.

Step 1: make a room schedule

Write one line per room. This table is your whole estimate in miniature, and every price later hangs off it.

Room	Size (m)	Floor (m²)	Perimeter (m)	Openings	Floor finish	Walls
Living room with kitchen	5.0 × 4.0	20.0	18.0	window, balcony door, door	wood	paint, splashback
Bedroom	3.5 × 3.0	10.5	13.0	window, door	wood	paint
Bathroom	2.0 × 2.0	4.0	8.0	door	tiles	tiles
Hall	2.5 × 2.2	5.5	9.4	four doors	wood	paint

For a room that isn’t a rectangle, split it into rectangles, add their areas, and walk round its outline for the perimeter. Measure to the finished wall faces, not to the middle of the walls.

Step 2: floor area per finish, plus waste

Group the rooms by the floor you want in them and add up their areas. Then add a waste allowance for cutting, because you always buy more than the net area.

Floor layout	Waste to add
Planks or laminate laid straight	5–10 %, 7 % is a fair middle
Herringbone parquet	15–20 %
Tiles laid straight	about 10 %
Tiles laid diagonally or in a pattern	about 15 %
Large-format tiles (60 × 120 cm and up)	12–15 %
Any finish in a room under 5 m² or with lots of corners	about 3 % more

Round up to whole packs or boxes. Floating floors also need underlay for the same area plus about 5 % for overlaps. If your kitchen units stand on the screed rather than on the finished floor, you can take their footprint off the kitchen’s floor area.

Step 3: wall area, net of openings

Wall area is the one people get wrong, because they price it by floor area. The formula is simple:

Wall area = perimeter × ceiling height − doors − windows

The perimeter comes from your schedule. The ceiling height is rarely on a sales plan: look for a section drawing, ask the agent, or measure on a viewing. As a guide, UK new-builds are often around 2.4–2.5 m, Polish blocks 2.5–2.7 m, and US homes 8–9 ft (2.4–2.7 m).

The plan gives the width of each opening; the height you assume:

Interior doors: about 2.0 m high (1,981 mm is the common UK size, 6 ft 8 in in the US).
Windows: the plan doesn’t show their height. Use an elevation if you have one, or 1.4–1.5 m as a first guess.
Balcony doors: about 2.2 m.

A door between two rooms comes off the walls on both sides. At normal heights, the wall area of a flat usually works out at 2.5 to 3 times its floor area. If your total is far outside that, recheck the heights.

Ceilings, on the other hand, are easy: a flat ceiling has the same area as the floor below it.

Step 4: paint in litres

Most interior emulsions cover 8–14 m² per litre per coat on smooth, sealed plaster; the tin says which. Plan on 10 m² per litre, which leaves room for rougher walls.

Litres = painted area × number of coats ÷ coverage per litre, plus about 10 %

Two coats is standard. Add a primer at roughly 0.1 litre per m² on new or patched plaster. For the US, the same rule reads as about 350–400 sq ft per gallon per coat.

Step 5: tiles, splashback and adhesive

Bathroom walls are where a plan-based estimate moves the most money, because the tiling height is a choice:

Full height: perimeter × ceiling height − the door.
To about 2.1 m: the same, at 2.1 m instead.
Wet zones only: the walls around the shower or bath, with the rest painted in moisture-resistant paint.

Take wall tiles off at the same waste as floor tiles in that layout; brick or half bond wastes about 12 %.

A kitchen splashback is the length of the worktop run on the plan times its height, often about 0.6 m between the worktop and the wall cabinets. Take it out of the painted area of that wall.

For materials that go with tiles: tile adhesive runs at about 4 kg per m² for ordinary tiles and 5–6 kg for large formats. Grout depends on tile size and joint width, but is a small line for most tiles; the manufacturer’s calculator will give you a figure. Add 10 % to both for what stays in the bag.

Step 6: skirting, doors and the things you count

Skirting length = room perimeter − door widths − the length of any kitchen run, then add about 7 % for mitres and offcuts. Skirting comes in lengths of about 2.4–2.5 m, so divide and round up.

Then count what is priced by the piece. The plan’s symbols tell you most of it; see floor plan symbols if a mark isn’t clear.

Interior doors: each quarter-circle arc is a door set: leaf, frame, casings, handle.
Sanitary fittings: bath or shower tray, toilet, basin or vanity.
Radiators, if you are replacing them.
Electrical points: sockets, switches and light points, if the plan has an electrical layout. Contractors in many markets price these by the point.
The kitchen: the length of the run on the plan in metres, since fitted kitchens are often priced per running metre.

What level of renovation you are pricing

The same quantities feed every level of work; what changes is how many lines you include.

Level	What it usually covers	Lines from your takeoff
Cosmetic	Paint, new floors over a sound base, new door handles or doors, light fittings	Floor, paint, skirting, perhaps doors
Standard	All of cosmetic, plus a new kitchen and bathroom	Everything above, plus tiles, fittings, kitchen run
Full (gut)	Strip to bare walls: rewiring, new pipes, replastering, new heating, sometimes moving walls	Every line, plus electrics by the point, plastering by the m² of wall and ceiling
Developer shell to finished	A new-build handed over with plastered walls, screed and services ready (in Poland, stan deweloperski to pod klucz)	All finishes and fittings, but no stripping out

The shell standard differs between developers, so read the contract’s list of what is included before you price. In Poland it often means plastered walls, screed, rough electrics and plumbing, radiators and windows, but not always tiles, doors or a kitchen.

2026 price ranges per square metre

Use these to check the total you build from your quantities, not in place of it. They are for the whole job, labour and materials, and they come from published 2026 cost guides. Guides disagree, so each row is a range, and your city and building can move you outside it.

Market	Cosmetic	Standard	Full or high spec	Notes and sources
UK	about £90–375/m²	£800–1,500/m²	£1,500–3,000+/m²	Standard and high-end: RenoCost 2026 per-m² rates, with London about 30–50 % above the north. Cosmetic: RenoCalc (June 2026) puts a cosmetic refresh of a 40–55 m² 1-bed at £5,000–15,000, and a full renovation at £20,000–40,000, both before VAT.
Poland	priced line by line	1,800–2,800 zł/m² from shell	3,500+ zł/m²	Finishing from developer shell, economy to mid-range, and premium (Oferteo, May 2026). Oferteo puts renovating a flat on the secondary market at 30–50 % more, because of stripping out. Big-city firms quote higher.
UAE	AED 150–300/sq ft (about AED 1,600–3,200/m²)	AED 350–600/sq ft (about AED 3,800–6,500/m²)	AED 600–1,200+/sq ft (about AED 6,500–13,000/m²)	Dubai apartments: cosmetic, mid-range, and premium to luxury gut (Vision Three, July 2026).
US	$25–60/sq ft (about $270–650/m²)	$60–130/sq ft (about $650–1,400/m²)	$200–400/sq ft gut (about $2,150–4,300/m²)	Condos (Block Renovation, August 2026). For mid-range work in New York and San Francisco, Block multiplies its baseline by 1.8–2.5.

Why your price per m² will differ

Small flats cost more per m². A 35 m² flat still needs a whole kitchen and a whole bathroom, and those are a large share of any budget: Dubai and US guides put kitchens and bathrooms at about 50–70 % of the total. Spread over fewer square metres, they push the rate up.
Flats cost more per m² than houses. Lift bookings, restricted working hours and protecting common parts add up; UK and Dubai guides put the premium at 10–25 %.
Building rules add fixed costs. A UK leaseholder usually needs the freeholder’s licence for alterations; a Dubai owner needs the developer’s or community’s NOC; a US condo owner signs an alteration agreement with the board. Each has fees and sometimes a deposit.

Worked example: a 40 m² one-bedroom flat

Here is the flat from the schedule above, 40 m² (about 430 sq ft), with 2.6 m ceilings, finished from a developer shell in Poland.

The quantities

Item	Net quantity	With waste, to buy
Wood floor: living room, bedroom, hall	36.0 m²	about 38.5 m², plus underlay
Bathroom floor tiles	4.0 m²	about 4.5 m² (small room)
Bathroom wall tiles, full height	19.4 m²	about 21.7 m²
Kitchen splashback, 2.4 m run × 0.6 m	1.4 m²	about 1.6 m²
Painted walls	87.6 m²
Painted ceilings	40.0 m²
Paint, two coats at 10 m²/l	25.5 l	about 28 l (about 7.4 US gal)
Primer at 0.1 l/m²		about 13 l
Skirting	32.1 m	about 34.3 m, 14 lengths of 2.5 m
Tile adhesive	24.8 m² of tiles	about 110 kg, five 25 kg bags
Interior doors	3	3
Bath, toilet, vanity	1 each	1 each

The walls come out at 87.6 m² painted plus 20.8 m² tiled: 2.7 times the floor area, inside the usual range. Tiling the bathroom to 2.1 m instead of full height would cut the wall tiles from 19.4 to 15.4 m².

The price

Priced at the unit rates in Oferteo’s May 2026 guide to finishing a flat in Poland:

Line	Rate	Total
Floor panels, 38.5 m²	60–120 zł/m²	2,300–4,600 zł
Tiles, 27.8 m² to buy	80–150 zł/m²	2,200–4,200 zł
Tiling labour, 24.8 m²	100–160 zł/m²	2,500–4,000 zł
Skim coat (gładź) on 127.6 m² of walls and ceilings	45–65 zł/m²	5,700–8,300 zł
Painting, 127.6 m²	20–35 zł/m²	2,600–4,500 zł
Interior doors with frames, 3	1,200–1,800 zł each	3,600–5,400 zł
Bathroom fittings	lump sum	4,000–6,000 zł
Kitchen units, 2.4 m run	1,800–3,000 zł per running metre	4,300–7,200 zł
Electrical points, assuming 30	100–150 zł each	3,000–4,500 zł
Total		about 30,000–49,000 zł

That is well under Oferteo’s own figure of 75,000–100,000 zł for a finished 40 m² flat at a mid standard, without appliances, and the gap is the lesson. The unit rates leave out lines that a builder’s quote includes: laying the floor, plumbing and fitting the bathroom, first-fix electrics, adhesive, underlay and skirting, rubbish removal and the contractor’s overheads. Oferteo puts labour at 40–50 % of a finishing budget. When your line-by-line total lands far below the per-m² check, look for the missing lines before you trust it.

The per-m² check for this flat is 1,800–2,800 zł/m², or 72,000–112,000 zł. With a 10–15 % contingency, a realistic budget is about 80,000–130,000 zł, before appliances, lighting and furniture. Parquet instead of panels, at 250–400 zł/m², would add about 7,000–11,000 zł.

The same plan in the UK, at RenoCalc’s 2026 range for a full 1-bed renovation, would be about £20,000–40,000.

How much contingency to add

The plan can’t show hidden problems, so every estimate carries a reserve. The guides agree on the order of it:

New-build or developer shell: 10–15 %.
Cosmetic work on a sound flat: about 10 %.
Full renovation of an older flat: 15–20 %.

Keep it as a separate line, and don’t spend it on upgrades before the walls are open.

Lowering the cost on the plan, before anyone quotes

The cheapest changes are the ones you make while the renovation is still a drawing.

Keep the bathroom and kitchen where they are. The plan shows where the water and waste pipes run; moving a toilet away from the soil stack is one of the costlier changes in a flat.
Keep the walls. Removing a partition adds demolition, making good, and new floor and skirting where it stood. A load-bearing wall adds an engineer, steel and approvals.
Tile less. Wet zones only, or 2.1 m instead of full height, is one of the biggest single savings in the takeoff.
Lay floors straight. Straight planks waste about 7 %, herringbone 15–20 %, and herringbone takes longer to lay.
Choose standard tile sizes. Large formats waste more, need more adhesive, and cost more to lay.
Run one floor through. Fewer finishes means fewer thresholds and less waste in small rooms.
Count the doors. An open doorway where you don’t need privacy saves a door set and its fitting.

When quotes arrive, set them next to your quantities. A quote for 60 m² of floor in a flat with 36 m² of it, or a missing line such as skim coating, is easy to spot once you have your own schedule.

Take the areas off your own plan

Upload the plan to FloorTo3D and type the flat’s floor area: the plan is scaled to it, and the top-down view shows every room with its area, the first column of the schedule above. Then switch between the five renovation styles to see the floors, tiles and paint you are pricing together, across the whole flat. FloorTo3D doesn’t price the work yet; the takeoff above and your local rates do that.

Check your own plan

Is the plan’s scale confirmed from written areas or dimensions?
Does every room have a line in your schedule, with floor area, perimeter and openings?
Do you know the real ceiling height?
Is your wall area 2.5–3 times the floor area?
Have you added waste to floors, tiles and skirting, and rounded up to packs?
Have you decided how high the bathroom tiles go?
Have you counted doors, fittings and electrical points?
Does your total land inside the per-m² range for your market and level?
Is there a contingency line of at least 10 %?

Questions

How much does it cost to renovate a flat per square metre?

In 2026, published guides put a standard renovation at about £800–1,500/m² in the UK, 1,800–2,800 zł/m² to finish a Polish developer shell, AED 3,800–6,500/m² for a mid-range Dubai apartment, and $650–1,400/m² for a mid-range US condo. Cosmetic work costs much less and full gut renovations much more. Small flats land at the top of each range because the kitchen and bathroom are fixed costs.

How do I estimate renovation costs myself?

Take the quantities off your floor plan room by room: floor area per finish, wall area net of doors and windows, tiles, skirting, paint and the items you count, such as doors and fittings. Add waste, price each line at local rates, then add a contingency of 10–20 %. Check the total against a per-m² range for your market.

How much does it cost to renovate a 40 m² flat?

It depends on the level of work and the market. In Poland, Oferteo puts finishing a 40 m² developer shell to a mid standard at 75,000–100,000 zł in 2026, without appliances; in the UK, RenoCalc puts a full one-bed renovation at about £20,000–40,000 before VAT. A cosmetic refresh of paint and floors costs a fraction of either.

How do you calculate wall area for painting?

Multiply the room’s perimeter by the ceiling height, then take off the doors and windows. For litres of paint, multiply the wall area by the number of coats and divide by the coverage on the tin, about 10 m² per litre per coat to be safe. Add 10 % for what stays in the tin and on the roller.

How much contingency should I add to a renovation budget?

About 10–15 % for a new-build or a cosmetic job, and 15–20 % for a full renovation of an older flat, where old wiring, uneven floors and damp only show once work starts. Keep the contingency as its own line in the budget.

Renovation cost per square metre: how to estimate it from a floor plan