UK House Build Cost Calculator (Oct 2025)

Core build

Floor area (m²)

Storeys

Region

Contingency (%)

Apply VAT (20%)

Rooms & lighting

Bedrooms

Bathrooms

Downlights (qty)

Paint & finishes

Wall area factor (× floor m²)

Ceiling factor (× floor m²)

Brickwork & roof

External wall area (m²)

Brick type

Roof area (m²)

Roof material

Extensions & landscaping

Extension area (m²)

Patio (m²)

Driveway block paving (m²)

Turf / lawn (m²)

Big-ticket rooms

Kitchens (qty)

Bathrooms (qty)

Unit costs (editable)

Defaults are October 2025 UK averages; edit to suit quotes. All figures are £ per unit.

New build (per m²)

Extension (per m²)

Kitchen (each)

Bathroom (each)

Downlight (each)

Paint (per m²)

Wire-cut bricks (£/1000)

Handmade bricks (£/1000)

Reclaimed bricks (£/1000)

Bricks per m²

Patio (per m²)

Block paving (per m²)

Turf (per m²)

Roof – concrete (per m²)

Roof – clay (per m²)

Roof – slate (per m²)

Subtotal

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Before contingency & VAT

Contingency

—

10% allowance

Total (incl. VAT)

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Live all-in estimate

Breakdown

Category	Quantity	Unit	Unit cost	Line total
Subtotal				—
Contingency				—
VAT (20%)				—
Grand total				—

Notes & assumptions

New‑build core uses a per‑m² allowance for shell + standard finishes. Edit to match spec and quotes.
Extension cost assumes single‑storey mid‑spec; change unit rate for double‑storey or premium finishes.
Painting area is floor m² × factors (walls & ceilings). Adjust factors for your design and ceiling heights.
All costs are indicative UK averages (Oct 2025) and exclude professional fees (architect, QS, engineers), planning, utilities upgrades, abnormal groundworks, and furniture/appliances unless included in your unit rates.