Pro rata rent calculator (UK)

Work out the pro rata rent for a tenant moving in before the rent day, or the refund when a tenancy ends partway through a paid month. It shows both UK methods side by side, and works room by room for an HMO.

Luke AshtonFounder of Bricky Bot and Based Lettings · Updated 19 October 2026

When you need pro rata rent

• Moving in before the rent day. The tenant starts on the 19th but every room in the house pays on the 1st, so the first payment covers the 19th to the 31st.
• Moving out partway through a period. A tenancy can end on a day that isn’t the end of a rent period: a leaving date you agree with the tenant, a surrender, or a possession date set by the court. The days after the tenancy ends that were already paid for go back to the tenant.
• Changing the rent day. Moving a tenant from paying on the 19th to the 1st needs one short period in between, charged pro rata.

Pro rata rent is still rent: keep it apart from the deposit, the holding deposit and bills on the statement, so the tenant can see what each payment is for.

How to calculate pro rata rent: the two UK methods

Both methods are used by UK landlords and agents. August’s calculator offers both (August, checked 19 October 2026), and OpenRent’s guide works per day of the calendar month (OpenRent, 18 May 2026). The calculator above shows your chosen method and the other one, so you can see why a tenant’s figure might differ from yours.

The calendar-month method gives a day in February more rent than a day in March, but the month always adds up to exactly one month’s rent. The 365-day method gives every day the same rent, so a part period costs the same in any month. When a part period runs across two months, the calculator uses each month’s own rate for its days.

No law says which method to use, and neither is wrong. Name one in the tenancy agreement (“part periods are charged at the monthly rent × 12 ÷ 365 per day”, or “… ÷ the number of days in that month”) and stick to it. Our free tenancy agreement template has a rent clause you can add it to.

Worked examples: move-in and move-out

Move-in. A tenant takes a room at £650 a month from Monday 19 October 2026, and the house pays rent on the 1st. The first period is 19–31 October, 13 days: £272.58 by calendar month (£277.81 by 365 days). The full £650 is then due on 1 November and on the 1st of every month after.

Move-out. A tenant paying £625 on the 1st agrees with you to leave on 12 January 2027, having paid for all of January. The 13th to the 31st, 19 days, relates to days after the tenancy ends: £383.06 goes back by calendar month (£390.41 by 365 days).

What the Renters’ Rights Act changed (England)

Three provisions in force since 1 May 2026 shape pro rata rent for assured tenancies, which most private tenancies now are. They are quoted here from legislation.gov.uk; check the full text before relying on them, as some parts commenced for specified purposes only.

• Rent periods of a month or less. A rent period must be 28 days or shorter, or monthly; a monthly tenancy can have a first period of a different length, up to 30 days (Housing Act 1988 section 4A, inserted by Renters’ Rights Act 2025, section 1). That first short period is where pro rata rent lives.
• No rent in advance, except the initial rent. Rent can’t be “due before the rent period for which it is payable”. The exception is initial rent paid between signing and the first day: rent for the first period and any later period that ends within the first 28 days (section 4B, inserted by section 8; the matching ban on taking rent before the tenancy is entered into is in Tenant Fees Act 2019, Schedule 1, as amended by section 9).
• Refunds after the end. A tenant is “entitled to be repaid any part of that rent… that relates to days falling after the end of the tenancy” (section 14ZC, inserted by section 10). The Act doesn’t say how to divide the days, which is why naming a method in the agreement matters.

In practice: with rent on the 1st and a move-in on the 19th, you can take the £272.58 for 19–31 October before the tenancy starts, but not November’s £650 as well, because November ends more than 28 days after the 19th. If the rent day is the 19th instead, the first full month is the first period and can be taken before day one. The Schedule 1 rules also stop an earlier period’s rent being set higher than a later one, so the part period can’t be used to load extra rent up front.

Pro rata rent in an HMO: one rent day or one per room?

In a shared house every room starts on a different day. There are two ways to run it, and both are lawful:

A six-room house on the 1st with two new tenants in a month might look like this: room 3 at £650 from 19 October pays £272.58 first; room 5 at £600 from 6 November pays £500.00 for 6–30 November (25 days of a 30-day month). Each room is its own tenancy, so work out each one separately in the calculator, with that room’s rent.

Deposits from the same rent

The calculator also checks the deposit and holding deposit you took against their caps, because they come from the same rent. A week’s rent is the annual rent divided by 52, the tenancy deposit is capped at five weeks’ rent (six if the annual rent is £50,000 or more) and a holding deposit at one week’s rent (Tenant Fees Act 2019, Schedule 1, paragraphs 2 and 3). For a £650 room that is £750 and £150. Don’t work a week out as a daily rate × 7: that gives a slightly different figure and can push a deposit over the cap. What you can later keep from the deposit depends on the check-in record: our free landlord inventory template writes one room by room.

Where pro rata rent goes wrong

• Off-by-one days. 19 to 31 October is 13 days, not 12. Count both ends.
• The leaving date. A tenant’s notice on a periodic tenancy should end on the first or last day of a rent period, so a refund usually comes from an agreed early date rather than the notice itself. Settle the date in writing first, then work out the refund. Our guide to tenant notice periods covers the dates.
• Rent increases. A section 13 increase takes effect at the start of a period, so it changes the monthly rent you put in here, not the part period. Our section 13 notice template works out the earliest start date, and the rent increase calculator gives the new rent for each room.
• Matching the payment. A one-off £272.58 is easy to miss against six rooms of round numbers. Note it against the room, so the next month’s check doesn’t flag the full £650 as a double payment.

Room by room, without the spreadsheet

Pro rata rent is one of the small jobs that pile up in an HMO: a new tenant’s first payment, a leaver’s refund, a bill split for the part month. Bricky Bot is an AI lettings team that does that work for the landlord, built by an HMO operator, with a person approving every message before it goes out. Rent stays in your own account; Bricky matches bank lines to each tenancy and prepares the statements, part months included.

See how it runs the rest of the house in our guide to HMO management software, or what an agent would charge for the same work with the property management fees calculator. Checking a deal first? The HMO rental yield calculator shows yield and cash flow room by room.

Questions landlords ask