Lease extension, freehold, marriage value, ground rent and more · Free & instant
Each tool has its own page with a worked example, its assumptions and its limits.
| Your situation | Use | Why |
|---|---|---|
| I own a flat and want to extend my lease | Lease Extension Calculator | Gives the full premium: ground rent, reversion and marriage value |
| I own a leasehold house and want the freehold | Freehold Purchase Calculator | Values ground rent plus reversion for a house |
| My lease is near or under 80 years | Marriage Value Calculator | Shows how much the 80-year line adds |
| My ground rent doubles or is index-linked | Ground Rent Capitaliser | Values escalating rents, the biggest swing factor for newer flats |
| I am buying and need stamp duty | SDLT Calculator | Includes surcharges for non-residents and additional properties |
| I want to check my service charge | Service Charge Calculator | Benchmarks against UK averages |
The first four share the same method. If you are weighing a lease extension against buying the freehold of a flat with your neighbours, see collective enfranchisement; for buildings, Right to Manage is a lighter alternative.
Our lease extension, freehold, marriage value and ground rent calculators use the standard statutory valuation method, with the same inputs throughout:
These are estimates, not valuations. A RICS valuer will use sales evidence and may use different rates, so always get a formal valuation before serving a notice. Our methodology page sets out the formulas and assumptions in full.
For a flat lease extension use the lease extension calculator. For a leasehold house use the freehold purchase calculator. If your lease is near or below 80 years, the marriage value calculator shows how much the 80-year line adds, and the ground rent capitaliser values doubling or index-linked rents.
They follow the standard statutory valuation method with a 5% rate and the Gerald Eve 2016 relativity table, so they give a useful estimate for budgeting. A RICS valuer will use sales evidence and may reach a different figure, so get a formal valuation before you serve a notice.
Yes. The lease extension calculator covers flats, and the freehold purchase calculator covers houses. Flat owners buy the freehold collectively, and that price is for the whole building, so it is not covered by a single-flat calculator.
Not yet. The 2024 Act provides for a 990-year extension, abolishing marriage value and new valuation rates, but those provisions are not in force. Until they are, the calculators use current law. See our reform tracker for the latest.
This calculator was built and is maintained by Rahul Tandon, an independent web developer and researcher. It models the standard statutory valuation approach (capitalised ground rent, reversion and marriage value) using published sources and the Sportelli deferment rate. The full formulas and limits are on the methodology page; see our editorial policy. LeaseVault is not a law firm or surveying practice, and the calculator gives estimates only, not a formal valuation or legal advice.
We’ll notify you when 2024 Act provisions come into force and when new premium rates are confirmed.