The rent maths every
landlord gets wrong
at least once.
Weekly to monthly. Monthly to fortnightly. Pro-rata for a mid-month start. The right figure for a rent review. Six calculators, one page. Not the BTL Calculator — this is for landlords who already own and let properties and need the everyday maths right.
Calculate your rent structure correctly
PDF summary and all 6 calculators included.
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Preview — what you'll get
What getting the rent maths wrong costs
Rent a landlord undercollects every year by using ×4 instead of ×52 ÷ 12 on a £185/week rent
Section 8 claim that failed because the landlord used an invalid rent increase process without Section 13 notice
Deposit deduction dispute triggered by an incorrectly calculated pro-rata rent at start of tenancy
Tenant application rejected with no guarantor discussion because the landlord didn't know the affordability rule
Illustrative examples. Six calculators exist to ensure none of these happen to you.
How it works
The right number in under a minute
Choose your calculator
Six calculators in one page — pick the one that matches your current situation. Weekly to PCM, pro-rata, fortnightly, rent review, or affordability check.
Enter one or two numbers
Every calculator updates live as you type. No submit button, no waiting. Results appear instantly with the working shown beneath.
Download or bookmark
Download a PDF summary of all your calculations. Or just bookmark this page — it saves your inputs locally so you can pick up where you left off.
What's included
Six calculators. Every day-to-day rent problem solved.
All update live as you type. All save locally in your browser. All in one page you can bookmark and return to whenever you need it.
Weekly Rent to PCM
Calc 1The most common landlord maths problem. Convert your weekly rent to the accurate calendar monthly figure using the correct ×52 ÷ 12 method — not the ×4 shortcut that undercounts.
PCM to Weekly Rent
Calc 2Convert a monthly asking rent to its weekly and daily equivalent — useful for listings, comparisons, and pro-rata calculations.
Pro-Rata Rent Calculator
Calc 3Calculate the correct rent for a partial month at the start or end of a tenancy. Uses the actual number of days in the month — not a fixed 30-day average.
Fortnightly Rent
Calc 4Get the accurate fortnightly equivalent of your monthly rent using the correct ÷ 26 method. Essential for landlords with Universal Credit tenants who pay fortnightly.
Annual Rent Review
Calc 5Calculate your new rent after a percentage increase — or work backwards from a new figure to find the percentage. Includes Section 13 notice requirements callout.
Rent Affordability Checker
Calc 6Instantly assess whether a prospective tenant's income meets the standard 2.5× and 3× affordability thresholds. Works for sole and joint tenancies.
Why landlords bookmark this
The rent maths a spreadsheet never bothered to explain
- Correct PCM formula — ×52 ÷ 12, not ×4 — with the annual shortfall shown
- Pro-rata uses the actual days in the start month, not a fixed 30-day average
- Fortnightly calculator built for Universal Credit payment schedules
- Rent review calculator flags Section 13 notice requirements automatically
- Affordability checker uses the standard 2.5× and 3× multipliers letting agents apply
- All inputs saved locally — nothing sent to a server, nothing to log in to
"I'd been using ×4 to convert weekly rent for years. Turns out I was undercounting by £62 a month. This calculator fixed that in about 10 seconds."
Private landlord— 3 properties, Leeds
"The pro-rata calculator alone is worth bookmarking. I used to spend 10 minutes checking this on a spreadsheet. Now it takes 30 seconds and the workings are shown on screen."
Portfolio landlord— 9 properties, Liverpool
"My UC tenant asked to pay fortnightly. I had no idea what the right figure was. This gave me the correct amount instantly with an explanation of the maths."
Buy-to-let landlord— Manchester
Getting the numbers right is just the start.
HomeDash tracks your rent received against what's due, flags missed payments automatically, and keeps your full financial picture up to date — across every property, every month.
Start tracking free — one property, foreverNo credit card required · Cancel any time