How the increase is calculated
Percentage. The increase is the current rent multiplied by the percentage. For example, 5% on £1,200 a month is £60 a month, or £720 a year, so the new rent is £1,260 a month (£15,120 a year).
Fixed amount. The increase is a set sum added to each rent payment. For example, £25 a week on £300 a week takes the rent to £325 a week. Over 52 weeks that is £1,300 more a year, and the calculator shows it as an 8.33% increase so you can compare it with a percentage rise.
Index-linked. The rent rises by the inflation figure named in the agreement, usually RPI or CPI, for the month the agreement specifies. Using 4% purely as an illustration, not a published figure, £1,000 a month rises by £40 to £1,040 a month, which is £480 more a year. Take the real figure from the ONS. In every case the new rent still has to be proposed with a Section 13 notice, as explained below.
All figures are rounded to the nearest penny. Yearly figures use 12 months for monthly rent and 52 weeks for weekly rent.
How rent increases work in England
Since the tenancy reforms took effect on 1 May 2026, almost all private tenancies in England are periodic assured tenancies, and fixed terms no longer apply in the way they once did. For a landlord this changes how rent is raised. The only lawful way to increase the rent on a periodic assured tenancy is to serve a Section 13 notice on the prescribed government form, Form 4A. Any rent review clause written into an older tenancy agreement is no longer a valid route.
Three timing rules govern when a proposed increase can take effect on a periodic tenancy. First, you must give the tenant at least two months notice before the new rent begins. Second, the rent can only be raised once in any 12-month period, so at least a year must pass since the last increase. Third, the rent cannot be raised at all during the first 12 months of the tenancy. Your earliest lawful effective date is simply the latest of these three dates, and the calculator above works it out for you.
There is no fixed cap on the amount of an increase, but it should reflect the market rent for a similar property in the same area. A tenant who believes the proposed figure is above market level can refer the notice to the First-tier Tribunal before the effective date. The tribunal can confirm the proposed rent or set it lower, but it cannot order a rent higher than the figure you proposed. Our guide on raising rent on periodic tenancies walks through the process step by step.
How to use this calculator
Start by entering the current rent and choosing whether it is paid per week or per month. Add the date the tenancy began, then tell the calculator when the rent was last increased. If you have never raised the rent on this tenancy, tick the box to say so and the first-year rule will be applied from the tenancy start date instead.
Next, enter the new rent you want to propose and the date you intend to serve the notice. The calculator defaults the service date to today, but you can change it to plan ahead. It then shows your earliest lawful effective date, tells you which of the three rules is setting that date, and works out the percentage increase between the current and proposed rent. You can optionally enter a date you would like the increase to start, and the calculator will confirm whether that date is valid or too early.
Use the result to plan your notice with confidence. Remember that the figures and dates are a guide to the timing rules and are not a substitute for the prescribed Section 13 form or professional advice.