Lease Extension Calculator UK
Instantly estimate your leasehold extension premium, including term value, reversion value, and marriage value. Perfect for flat owners considering extending their lease.
Premium Estimate
Enter your lease details to estimate the extension premium
The estimated value of your property if it were owned outright, with no lease restrictions.
How many years are left on your current lease.
The annual ground rent you currently pay to the freeholder.
The number of years typically added under a statutory lease extension.
The value of your existing short lease as a percentage of the freehold value. This is usually taken from published relativity graphs.
The rate used to value the freeholder’s lost ground rent income.
The rate used to value the freeholder’s delayed reversionary interest.
Your Premium Estimate
Term value, reversion value, marriage value, and full breakdown
Enter your lease details above and click Estimate Premium to reveal your lease extension breakdown.
Example Premium Estimates
Illustrative premium estimates at a 92% relativity, £150 ground rent, 6% capitalisation rate, and 5% deferment rate, so you can see how the numbers shift with years remaining.
| Freehold Value | Years Remaining | Marriage Value Applies? | Estimated Premium | % of Freehold Value |
|---|---|---|---|---|
| £200,000 | 95 years | No | ≈ £3,100 | ≈ 1.6% |
| £250,000 | 85 years | No | ≈ £5,600 | ≈ 2.2% |
| £300,000 | 70 years | Yes | ≈ £14,900 | ≈ 5.0% |
| £350,000 | 60 years | Yes | ≈ £26,800 | ≈ 7.7% |
| £400,000 | 50 years | Yes | ≈ £43,600 | ≈ 10.9% |
| £450,000 | 40 years | Yes | ≈ £70,900 | ≈ 15.8% |
Lease Extension Calculator FAQ
Everything you need to know about lease extension premiums, marriage value, and extending a leasehold property in the UK.
A lease extension adds years onto the remaining term of a leasehold property, typically a flat, in exchange for a one-off payment called a premium, usually paid to the freeholder and often accompanied by reducing the ground rent to a peppercorn (nil) amount.
The premium is traditionally made up of three parts: the term value, which compensates the freeholder for lost ground rent income; the reversion value, which compensates them for delaying when the property reverts to them; and, where applicable, a share of the marriage value created by the extension.
Marriage value is the increase in total value created when a short lease and the freehold are combined into one longer lease. Under the traditional valuation method it typically applies when the unexpired lease term is under 80 years, and is usually split 50/50 between leaseholder and freeholder.
Yes. While a calculator can give a useful estimate, the actual premium is negotiated or determined based on a formal valuation from a qualified surveyor, since factors like relativity percentages and comparable evidence can significantly affect the figure.
Under UK leasehold reform legislation, qualifying leaseholders have historically had the right to extend their lease by 90 years on top of the remaining term, with the ground rent reduced to a peppercorn. Recent reform legislation has proposed further changes, so it’s worth checking the current rules before relying on this figure.
The Leasehold and Freehold Reform Act introduces changes intended to simplify and potentially reduce lease extension premiums, including proposals around marriage value. As the rules are being phased in, always confirm the current position with a specialist leasehold valuer or solicitor.