Free UK Rebuilding Cost Calculator for Insurance

Rebuilding Cost Calculator

Estimate costs for UK insurance purposes

Property Type

Floor Area (m²)

Region

Year Built

Construction Type

Storeys

Outbuildings Area (m²)

Extra Features (% uplift) Swimming pool, garage, high-end kitchen etc.

£0

Estimated rebuild cost (2025 rates, inc. 5% inflation)

How to Arrive at Accurate Figures

Measure total internal floor area across all floors, excluding stairs.

Select property type matching your home’s structure and era.

Adjust for region using BCIS location factors; London adds 15% typically.

Add outbuildings separately at reduced rates.

Estimate extras percentage for non-standard items like lifts or basements.

Click calculate; review breakdown and update insurance sum insured.

Calculation Principles

Figures derive from BCIS All Rebuild Cost Indices, averaging £2,200/m² for standard new builds in 2025, uplifted 5% for inflation. Multipliers adjust for type (flats lower due to shared walls), age (older properties cost more to match period features), materials (stone 15% premium), and storeys (heights increase scaffolding). Regional variances reflect labour/material costs; outbuildings use £1,800/m². Extras apply as percentage to capture fittings. Results approximate day one reinstatement cover needs.

Rebuild vs Market Value

Aspect	Rebuild Cost	Market Value
Basis	Replacement cost new	Location & land value
Land	Excluded	Included (major factor)
London Example (100m²)	£280,000	£650,000+
Depreciation	Not applied	Reduces for age/condition
Insurance Use	Sum insured limit	Not relevant

Common Queries

Why higher for detached houses?

Full external walls increase material/labour vs shared walls in terraces/flats.

Include garage?

Yes, add as outbuildings area; separate from main house footprint.

Listed property adjustment?

20% uplift covers specialist matching of original features.

Annual review needed?

Yes, costs rise 4-7% yearly; recalculate post-extensions or index changes.

Underinsurance risk?

Average 20% shortfall leads to average clause; full rebuild sum prevents partial payouts.

Pitfalls to Avoid

Using market value as proxy – ignores land exclusion.
Omitting extensions/conversions – add full floor area.
Ignoring region – Scotland 5-10% below England average.
Forgetting inflation – BCIS index rose 5.2% in 2024.
Overlooking basements/swimming pools – treat as 20-30% extras.

References

Building Cost Information Service (BCIS), RICS. (2025). All Rebuild Cost Index: National Averages and Regional Factors.
Association of British Insurers (ABI). (2024). Home Insurance Underinsurance Report.
HM Government. (2023). Approved Document A: Structure – Rebuild Cost Guidelines.
Property Services Agency. (2025). Elemental Cost Breakdowns for Domestic Properties.