Leasehold Extension Cost Estimator
Use this leasehold extend calculator to get a quick estimate of the premium payable for a statutory lease extension (typically +90 years and peppercorn ground rent).
What this leasehold extend calculator does
This calculator gives a practical estimate of lease extension premium by combining three core valuation components: term value, reversion value, and (if applicable) marriage value. It is designed for quick planning, budgeting, and comparing scenarios before speaking with a surveyor or solicitor.
If your lease is approaching the 80-year mark, this is especially useful. Once the term drops below 80 years, marriage value often increases the cost significantly.
How the estimate is built
1) Term value (lost ground rent)
The freeholder loses future ground rent income once a statutory extension sets rent to a peppercorn. The calculator discounts that rent stream using your capitalisation rate.
2) Reversion value (delay in getting the property back)
Without extension, the freeholder regains vacant possession sooner. With extension, that event is pushed further out. The difference in discounted value is part of the premium.
3) Marriage value (usually below 80 years)
Marriage value reflects the uplift in lease value after extension. In many statutory cases, the uplift is shared 50/50 between leaseholder and freeholder when the term is under 80 years.
Input guide for better accuracy
- Property value: Use open-market value as if lease length were not a discount issue (long lease equivalent).
- Years remaining: Use exact term from your lease documents.
- Ground rent: Enter current annual rent; escalating rents require specialist adjustment.
- Relativity: If you have a surveyor’s figure, use it. Otherwise, the auto option gives a broad estimate.
- Fees: Include your valuer and solicitor plus landlord’s recoverable professional costs.
Why the 80-year threshold matters so much
Many leaseholders focus on this threshold because marriage value can materially raise the premium once remaining term dips below 80 years. In plain terms:
- At 80+ years, costs are often lower and more predictable.
- At below 80 years, premium can jump, sometimes sharply.
- As term falls further, marketability and mortgage options may also weaken.
Example scenario
Suppose a flat has a long-lease value of £450,000, 78 years remaining, and £250 annual ground rent. With typical rates and fees, the leasehold extend calculator may produce a premium in the tens of thousands, plus costs. If the same flat had 83 years left, the estimated premium could be lower because marriage value may not be triggered.
Ways to reduce surprises before you extend
Get specialist valuation advice early
A specialist enfranchisement surveyor can produce stronger relativity evidence and help you decide opening offer levels.
Prepare your paperwork
Have lease, title documents, service charge statements, and freeholder contact details ready to avoid avoidable delays.
Budget for total cost, not just premium
Lease extension cost usually includes more than the premium: valuation, legal fees, and disbursements can add a meaningful amount.
Quick FAQ
Is this calculator UK-specific?
Yes, the model is aligned with common UK lease extension concepts and terminology.
Does this replace a professional valuation?
No. It is a planning tool. Formal negotiations should rely on professional advice.
Can I use it for informal freeholder offers?
Yes, as a benchmark. But informal deals can include different terms (e.g., revised ground rent), so compare carefully.
Final thought
A lease extension can protect value, saleability, and lending options. Use this leasehold extend calculator to run scenarios, then speak to a specialist valuer and solicitor to convert your estimate into a defensible negotiation strategy.