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RentCharter
Free UK calculator

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.

Step 1 of 5 · About a minute

Where do you live?

Upload your tenancy to auto-fill everything and unlock your full result for free — or just enter your postcode to do it manually.

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We use the postcode prefix to find local market rents.
Helps us match if your postcode isn't in our sample yet.
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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 compares your proposed rent to the local lower quartile, median and upper quartile.

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 on rent increases for most assured shorthold tenancies in England. What matters is whether the rent reflects the open-market rate for similar properties locally. RentCharter compares your figures to 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 and is free to use.

See also: market rent checker · Section 13 checker · rent increase rights in England.