🧮 Interactive Calculator · Updated June 2026 · Real UK Data

Garage Conversion Cost Calculator UK

Estimate the 2026 cost of converting your garage into a habitable room — by size, finish and region. Real building-quote figures with a realistic low–mid–high range. No email required.

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Garage conversion costs in the UK (2026)Typical installed prices by option — 2026 — Source: BestBuilders.co.uk · typical UK prices 2026 · excludes VAT & access variances Garage conversion costs in the UK (2026) Typical installed prices by option — 2026 £0 £10k £20k £30k £40k Single Habitable room £8.5k–£11.5k Single + en-suite With plumbing £11.1k–£14.9k Double Habitable room £15.3k–£20.7k Double + kitchenette Annexe £23.7k–£32.1k Large / detached Habitable room £20.4k–£27.6k Source: BestBuilders.co.uk · typical UK prices 2026 · excludes VAT & access variances BestBuilders.co.uk
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Estimate Your Garage Conversion Cost

Choose your garage size, finish and region for an instant 2026 estimate.

Methodology

How This Calculator Works

This calculator combines your garage size with a finish multiplier and real 2026 UK building-quote pricing, then applies a regional labour multiplier.

Size Base Prices (building work)

  • Single garage ~£10,000
  • Double garage ~£18,000
  • Large / detached ~£24,000
  • Finish: + en-suite / plumbing ×1.30 · + kitchenette / annexe ×1.55

Covers insulation, floor, new openings, heating, electrics and finishes — excludes furniture.

Regional Multipliers

  • London 1.25× · South East 1.12×
  • Midlands & East 1.00× (baseline)
  • South West & Wales 0.95×
  • North & Scotland 0.90×

Low/high reflect a ±15% spread around the mid estimate. A real quote follows a site survey.

Typical Garage Conversion Costs (2026)

Building work (insulation, floor, openings, heating, electrics, finishes; excl. furniture), Midlands baseline (±15%).

Garage sizeFinishCost range
SingleHabitable room£8,500–£11,500
Single+ en-suite / plumbing£11,050–£14,950
DoubleHabitable room£15,300–£20,700
Double+ kitchenette / annexe£23,715–£32,085
Large / detachedHabitable room£20,400–£27,600

These figures power the calculator above — enter your own spec for a tailored estimate. For the full breakdown, read our complete cost guide.

Frequently Asked Questions

How much does a garage conversion cost in 2026?

A single garage conversion typically costs £8,000–£18,000 in 2026, a double £15,000–£28,000, and one with plumbing for an en-suite or kitchenette £18,000–£35,000.

Do I need planning permission?

Converting an attached garage within the existing walls is usually permitted development. Conservation areas, some new-build estates and changes to the external appearance can need permission.

Does it need Building Regulations?

Yes — a conversion needs Building Regs approval covering insulation, damp proofing, ventilation and structure, even when planning permission is not required.

How long does it take?

Most garage conversions take 2–4 weeks depending on insulation, new openings and any plumbing or electrical work.

Does it add value?

A well-finished conversion can add around 10–15% to a home's value, provided off-street parking is not essential to local buyers.

How accurate is this garage conversion cost estimate?

It is a guide from average UK 2026 prices for the conversion type and size you pick, not a fixed quote. Your true cost hinges on the existing structure, foundations, damp, insulation needs and how you finish the room. A single integral garage differs from a detached double, so confirm with a site survey after budgeting.

What does the garage conversion estimate include and exclude?

The figure typically covers infilling the door, insulating walls, floor and roof, plastering, basic electrics, a window and 20% VAT. It usually excludes upgrading foundations, tanking against damp, heating or radiator connections, plumbing for a bathroom or kitchen, and decorating. If your garage needs structural or damp work, add that to the guide figure.

Why might a builder's quote exceed this estimate?

A calculator assumes a sound, standard garage. A builder prices what they actually find, such as shallow foundations, damp floors, a sagging roof or a shared party wall, all of which add cost. Building Regulations upgrades for insulation and ventilation, plus higher London and South East labour rates, also push a real quote above an average estimate.
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Reviewed by the BestBuilders editorial team on 2 July 2026 · Next scheduled review: October 2026 · See our editorial standards.
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