Before using the calculator, you must read and agree to this disclaimer. This disclaimer was last updated in January 2026.

About the calculator

This calculator provides a general estimate of the premium (price) for extending the lease of a flat. It is based on national data and does not include local factors.

Important notes

  • The estimate is not a professional valuation and should not be used in legal or tribunal proceedings. Always consult a qualified surveyor or property lawyer for accurate costs.
  • You must have at least 50 years remaining on your current lease to use the calculator or 40 years in central London. If your lease has less time remaining, get advice from a chartered surveyor or valuer.
  • The calculation does not include other costs of extending a lease, such as:
    • your landlord's reasonable professional fees
    • your own professional fees like solicitors, surveyors and a formal valuation
    • stamp duty land tax

Liability

We are not responsible for any actions or losses resulting from reliance on this estimate. Laws and valuation methods may change, so always seek professional advice.

More information

Find out more about lease extension for flats

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