Don't rely on a free rebuild cost calculator - do this instead

It’s a common assumption that a free online rebuild cost calculator will give you an accurate idea of how much to insure your home for. Unfortunately, that assumption could leave you tens of thousands of pounds out of pocket.

Many calculators use outdated averages and broad assumptions. They can’t answer the critical question: “How much does it cost to rebuild my house?” accurately. That’s because they fail to reflect your home’s specific features, materials, and location. And when the rebuild cost of your home is wrong, the consequences can be serious.

Thankfully, there’s a better way to get clarity — a professional alternative that’s fast, trusted, and far more accurate.

Not sure where you stand? You can find out the likelihood of your property being accurately insured by clicking the button below.

Try the Rebuild Checker

What is a rebuild cost calculator?

A rebuild cost calculator is an online tool designed to estimate the home rebuilding cost of a property. But these tools often miss the mark because they:

• Use broad, generic cost data not tailored to your home

• Fail to include renovations, extensions, or bespoke finishes

• Don’t adjust for regional variations in construction costs

• Are rarely updated with real-time pricing

This can result in your home being significantly under- or over-valued for insurance purposes.

Why inaccurate estimates put you at risk

Many UK homeowners believe their insurer automatically keeps valuations up to date, or that a rebuild cost calculator is “close enough.” But the data tells a different story:

• 70% of UK residential properties are underinsured

• Underinsured properties are typically covered for just 63% of the amount they should be

• 25% are overinsured, leading to inflated premiums

Data taken from RebuildCostASSESSMENT.com's annual infographic 2024, which you can find here.

This is sadly a far too common issue. It’s a hidden financial risk that could affect your future.

What is a desktop rebuild cost assessment?

A desktop rebuild cost assessment is a remote valuation service conducted by chartered surveyors. It offers the same professional accuracy as a site visit — but faster, more efficient, and considerably more affordable.

Here’s what sets it apart:

• Uses images, floorplans, planning history and digital mapping to assess your home

• Factors in extensions, materials, property type, and build quality

• Uses up-to-date cost data, including regional labour rates and inflation

• Accepted by insurers and mortgage lenders as a credible valuation

It’s designed for homeowners who want trusted accuracy, without unnecessary delays or disruption.

Our ‘Regulated by RICS’ status means you can feel confident in our standards and the quality of our service.

Learn more about RICS

Rebuild cost calculator vs. desktop assessment: what’s the difference?

Feature	Free Rebuild Cost Calculator	Professional Desktop Assessment
Who conducts it?	Automated software	Chartered surveyor
Data used	Broad averages	Property-specific details
Accuracy	Approximate	Precise rebuild value
Includes renovations?	❌	✅
Updates for inflation & region?	❌	✅
Accepted by mortgage lenders?	❌	✅

When should you get a desktop assessment?

A desktop rebuild cost assessment is ideal if:

• Your home has been extended or modernised

• Your property has unique features or is listed

• It’s been 3 years or longer since your last valuation

• You’ve ever asked, “How much does it cost to rebuild my house?”

• You want to be confident that the rebuild cost of your home is accurate

What’s the first step? Try the free rebuild checker

If you're unsure whether your property is correctly insured, the best first step isn’t a rebuild cost calculator — it's the Rebuild Checker.

This free tool doesn't attempt to guess your home rebuilding cost, unlike calculators. Instead, it analyses real data from over 150,000 professionally assessed properties across every UK postcode area to estimate the likelihood that your home is under, over, or accurately insured.

• No cost, no commitment

• Results based on your postcode, not assumptions

• Works for both residential and commercial properties

• The ideal way to understand your current risk before booking an assessment

It’s the smarter way to see where you stand — and what you should do next.

Try the Rebuild Checker now

Watch our video below for a further explanation on our rebuild checker:

Secure your home with confidence

Whether you’ve already insured your home or are about to renew, don’t rely on a rebuild cost calculator alone. It might offer a fast answer, but not an accurate one.

Choose precision, peace of mind, and professional credibility. Check your likelihood of accurate insurance and get a desktop rebuild cost assessment to ensure you’re properly protected, not just guessing.

Book your assessment today

Know your true home rebuilding cost and get insured with confidence. Book your rebuild cost assessment now and make sure your property’s cover reflects its true value.