Rent increase calculator
Work out the percentage and pound impact of a proposed rent increase — and see how it compares to typical local market rents in your postcode.
How the calculation works
The calculator runs three numbers off your inputs:
- Percentage change = ((proposed − current) ÷ current) × 100.
- Annual impact = (proposed − current) × 12.
- Market context places your proposed rent against the local market range from ONS rent statistics.
Common questions
How do I calculate the percentage of a rent increase?
Subtract the old monthly rent from the new monthly rent, divide by the old rent, then multiply by 100. For example: a rent rising from £1,500 to £1,650 is a 10% increase.
Is a 10% rent increase reasonable in the UK?
There is no fixed legal cap or percentage limit on rent increases for most private tenancies in England. Since 1 May 2026 a landlord has to use a Section 13 notice (with at least 2 months' notice, no more than once a year), and if you refer it, the First-tier Tribunal decides whether the new rent is above open-market rent for similar properties. RentCharter compares your figures with local market data so you can see how your increase looks in context.
What is a fair rent calculator?
A 'fair rent calculator' typically means a tool that compares a proposed rent to local market rates so a tenant can decide whether to accept, negotiate or challenge it. RentCharter is one such tool: the rent check is free, and the optional evidence pack is £9.99, or free if you upload your tenancy agreement.
See also: market rent checker · Section 13 checker · rent increase rights in England.
What the number actually means
Overview of the rules under the Renters' Rights Act 2025.
Read moreCounter-offer evidence, the lines that land, and what to put in writing.
Read moreThe 2-month rule under the RRA 2025 — and what an informal proposal does and doesn't trigger.
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