Rent Increase Calculator

Use this free Rent Increase Calculator to work out exactly how much more you would pay if your landlord proposes a higher rent under the Renters' Rights Act 2026 (in force 1 May 2026). Enter your current rent and either the proposed new rent or a target percentage, and the tool instantly shows the increase in pounds, the percentage rise, the extra cost over a full year, and the key legal dates a landlord must respect.

Since 1 May 2026, the only lawful way to raise rent on a private assured tenancy in England is a Section 13 notice on Form 4A. Your landlord must give at least 2 months' notice, can only increase the rent once every 12 months (52 weeks), cannot raise it in the first year of the tenancy, and the new figure must be no higher than the open market rent. CPI- or RPI-linked rent-review clauses are now void. This calculator is built for both tenants checking a Form 4A and landlords planning a compliant increase.

How the rent increase calculator works

The maths is simple but the legal context matters. The calculator computes:

• Increase amount = proposed rent − current rent.
• Percentage rise = (proposed − current) ÷ current × 100.
• Annualised difference = the increase × 12 for monthly rent, or × 52 for weekly rent — the true extra cost over a year.
• Earliest lawful effective date = the later of (a) today plus the minimum 2 months' notice, and (b) 52 weeks after your last increase or tenancy start, reflecting the once-a-year limit.

If you enter a target percentage instead of a pound figure, the tool multiplies your current rent by (1 + percentage ÷ 100) to find the proposed rent, then runs the same calculation. Under the Renters' Rights Act 2026 every increase must be at the open market rent and is served via Form 4A; index-linked (CPI/RPI) clauses can no longer be used.

Worked example

Suppose your current rent is £1,200 per calendar month and your landlord proposes £1,290 per month on a Form 4A.

• Increase: £1,290 − £1,200 = £90.00 per month.
• Percentage rise: 90 ÷ 1,200 × 100 = 7.50%.
• Extra cost over a year: £90 × 12 = £1,080.00.
• If the notice is served today, the earliest the new rent can lawfully take effect is today plus 2 months (and no sooner than 52 weeks after your last increase).

If you think £1,290 is above the open market rent for a comparable local property, you can refer the increase to the First-tier Tribunal before it takes effect, and the tribunal can set a rent that is the same, higher or lower.

Frequently asked questions

How much notice must a landlord give to increase rent in 2026?

At least 2 months. Since 1 May 2026 the landlord must serve a Section 13 notice on Form 4A giving a minimum of two months before the new rent can start.

How often can my rent be increased?

Only once every 12 months (52 weeks), and never during the first year of the tenancy. The calculator uses your last-increase date to flag the earliest lawful effective date.

Is there a legal cap on how much the rent can rise?

There is no fixed percentage cap, but the new rent must be no higher than the open market rent — what the property would let for today. CPI or RPI rent-review clauses are now void.

Can I challenge a rent increase?

Yes. If you believe the proposed rent is above the open market rate, you can apply to the First-tier Tribunal (Property Chamber) before the increase takes effect. The tribunal decides the rent, which may be the same, higher or lower than proposed.

Source: GOV.UK — Renting out your property: Rent increases and the Renters' Rights Act overview for tenants. Figures verified June 2026. This tool is for general guidance and is not legal advice.

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