Rebuild Cost Calculator

The rebuild cost of a house is what it would cost to completely rebuild it from the ground up if it were destroyed — for example by fire or flood. It is the figure your buildings insurance sum insured should be based on, and it is almost always lower than the market value or sale price, because the rebuild cost excludes the value of the land. This free rebuild cost calculator gives you an instant, no-sign-up estimate using the standard insurance industry method: your home's internal floor area multiplied by a regional cost per square metre, plus allowances for demolition, professional fees, garages and outbuildings. It is built for UK homeowners checking or renewing a policy, landlords, and anyone who has received a renewal quote and wants a quick sanity check against under- or over-insurance. For a standard brick-and-block house it gives a reliable ballpark in seconds; for listed, period or non-standard properties you should still commission a professional reinstatement survey.

How rebuild cost is calculated

The calculator follows the methodology used by the Association of British Insurers (ABI), RICS and the BCIS House Rebuilding Cost Index:

1. Floor area × rate per m². A base rebuild rate is chosen for your property type (roughly £1,850–£2,100/m² for standard-specification homes in 2026), then adjusted.
2. Quality factor. Basic finishes reduce the rate (×0.85), while good or high-end specifications increase it (×1.20 to ×1.45).
3. Regional multiplier. Labour and access costs vary by region, from about ×0.90 in Northern Ireland to ×1.20 in London.
4. Extras. A garage or outbuildings are added, plus optional demolition and site clearance (about £60/m²) and professional fees (architects, surveyors, building control) at 12.5% of the build cost.

The result is shown as a central estimate with a likely range of −10% to +15% to reflect real-world variation in quotes. Land value is always excluded, and reinstatement after an insured loss is normally zero-rated for VAT.

Worked example

Take a detached house with an internal floor area of 120 m² in the Midlands, built to a standard specification, with no garage and no extra options selected:

• Rate used: £2,100 × 1.00 (standard) × 1.00 (Midlands) = £2,100/m²
• Structure: 120 m² × £2,100 = £252,000
• Central rebuild estimate: £252,000 (likely range £226,800 to £289,800)

If you then add a single garage (+£18,000), demolition and site clearance (120 × £60 = £7,200) and professional fees at 12.5% of the £270,000 build cost (£33,750), the central estimate rises to about £310,950. This is the figure you would want your buildings sum insured to cover — not the market value.

Frequently asked questions

Why is the rebuild cost lower than my home's market value?

Market value includes the land your home sits on, its location and demand. Rebuild cost is purely the bricks-and-mortar cost of reconstruction, so for most homes — especially in high-value areas — the rebuild figure is significantly lower than the sale price. In a few cases (older homes in low-value areas) the rebuild cost can exceed market value.

What is included in the rebuild cost?

The structure, demolition and site clearance, professional fees (architects, surveyors, building control), bringing the property up to current building regulations, and outbuildings such as garages. It excludes the land, contents and, normally, VAT (insured reinstatement is usually zero-rated).

Do I need a survey for a listed or non-standard property?

Yes. Listed buildings, period homes and non-standard construction (timber frame, thatch, stone, steel or concrete frame) can cost 25%–100% more to reinstate and fall outside a simple per-m² estimate. Commission a professional RICS reinstatement cost assessment for these and for any home with a rebuild value above roughly £500,000.

What happens if I under-insure my home?

If your sum insured is below the true rebuild cost, insurers can apply "average" and cut your payout proportionally even for a partial claim. For example, insuring for 70% of the rebuild cost can mean only 70% of a claim is paid. Use this calculator to set an accurate sum insured and review it each year, as rebuild costs have risen sharply with materials inflation.

Sources & method

Figures are based on the standard reinstatement methodology published by the Association of British Insurers and the BCIS (Building Cost Information Service) House Rebuilding Cost Index, and on RICS reinstatement-valuation guidance. See the ABI guide to buildings insurance and the free ABI/BCIS rebuild calculator. Per-m² rates are 2026 estimates and vary by location, age and condition — this tool gives guidance only and is not a substitute for a professional survey.