Reviewed for UK readers: September 2026.
Pro rata rent is used when rent needs to cover only part of a rental period, such as moving in after the normal rent date or agreeing a tenancy end date part way through a month. Unlike salary, there is no single universal pro rata rent convention for every tenancy, so check the tenancy agreement before choosing the formula. Our pro rata calculator UK is designed for salary and work patterns; this guide explains rent separately.
The two common approaches are a calendar-day method for the relevant month and an annual daily-rate method.
Quick answer
- Check the tenancy agreement for the agreed method.
- Calendar method: monthly rent ÷ days in that month × chargeable days.
- Annual method: monthly rent × 12 ÷ 365 × chargeable days.
- Confirm whether the first and last day are both chargeable.
Calendar-month method
For £1,200 monthly rent in a 30-day month, the daily rate is £40. If the tenant is responsible for 12 days, pro rata rent is £480. In a 31-day month, the daily rate for the same monthly rent would be about £38.71.
Annual daily-rate method
Another approach converts annual rent to a daily amount: £1,200 × 12 = £14,400 annual rent; £14,400 ÷ 365 ≈ £39.45 per day. Twelve chargeable days would therefore be about £473.42. This can differ from the calendar-month method.
Why the tenancy agreement matters
The calculation method is often a contractual issue. Landlord and tenant should agree which dates are included and how partial periods are charged. Do not switch methods only because one gives a more favourable number.
Move-in example
If a tenancy starts on 20 September and the agreement uses the calendar-month method with both 20 and 30 September chargeable, there are 11 chargeable days. At £1,200 per month: £1,200 ÷ 30 × 11 = £440.
Move-out and rent paid in advance
Where rent is paid in advance, a partial final period may involve a balancing payment or refund. The tenancy terms and agreed surrender/end date determine whether a pro rata adjustment is due.
Keep the agreed rent method in writing
Because different pro rata rent methods can produce different results, record the agreed formula and the exact chargeable dates in writing. That is especially important for tenancy start dates, early surrender agreements and refunds of rent paid in advance.
A calculator can perform the arithmetic, but it cannot decide which method your tenancy requires. The contract and any later written agreement should control that choice.
Use the calculator
For a quick gross salary estimate, use the Pro Rata Calculator UK. Enter the full-time salary and your hours, days or FTE, then compare the result with your contract or payroll figure.
Frequently asked questions
Is pro rata rent always monthly rent divided by 30?
No. Calendar months contain different numbers of days, and some agreements use an annual daily-rate method.
Should I divide annual rent by 365?
Only if that is the agreed method. Check the tenancy wording or written agreement between the parties.
Do I count the move-in day?
That depends on the agreed chargeable period. Make the included dates explicit before calculating.
Is pro rata rent the same as a rent refund?
Not necessarily. It is simply a proportional calculation; whether money is owed depends on the tenancy arrangements and payments already made.
This article is general information, not personalised legal, tax or payroll advice. Employment contracts, collective agreements and individual circumstances can change the correct result.