UtilibyWritten by the Utiliby editorial team · Last updated October 12, 2026 · Rules and formulas reviewed October 2026
What this rent calculator does
Rent questions come in four shapes, and this free online tool handles all of them: how much to pay for a partial month, what a rent increase really means, how to split rent fairly between roommates and how much rent you can afford. Each one has its own tab, a clear result and a printable summary, with no sign-up and no data leaving your browser.
The prorated rent calculator compares the actual-days, 30-day and 365-day methods and gives the total due at move-in with the deposit and fees. The rent increase calculator turns a percentage or fixed rise into a new rent, a yearly cost and the first date the new rent is due after the notice period. The roommate rent splitter divides rent by room size or equally with premiums and discounts, and the affordability checker tests a rent against the 30% rule and landlord income multiples.
How to use the calculator
- Pick a tab. Prorated rent, Rent increase, Split rent or Affordability.
- For prorated rent, enter the monthly rent, choose move-in or move-out, set the date and method, then add extras, deposit and fees.
- For a rent increase, enter the current rent, the increase, the date the notice is given and the notice days, plus any cap that applies.
- For a split, enter total rent and utilities, choose the number of people, then name each room and enter its size and any premium or discount.
- For affordability, enter your gross monthly income and the rent you are considering.
- Export. Print, download a CSV or copy the summary for the tab you are viewing.
How prorated rent works
Prorated rent is rent for part of a month. It applies when a lease starts or ends mid-month, when you move out early, or when rent changes during the month. The usual formula is monthly rent ÷ days in the month × days of occupancy.
| Method | Daily rate | When it is used |
|---|---|---|
| Actual days | Rent ÷ days in that month | Most common; February days cost more than July days |
| 30-day month | Rent ÷ 30 | Simple convention in some leases |
| 365-day year | Rent × 12 ÷ 365 | Same daily rate all year |
Worked example. Rent is 1,800 and you move in on November 15. November has 30 days, so the daily rate is 60 and you stay 16 days (15th to 30th). Prorated rent is 960. With a 365-day year the rate is 59.18 and the charge is 946.85, a small difference of 13.15. Add a 1,800 deposit and the first month's total due is 2,760.
Understanding rent increases
A rent increase can be stated as a percentage or a fixed amount. Both are shown as a new rent, a monthly and yearly cost, and a multi-year table. The notice date matters: a landlord usually has to give written notice a number of days before the new rent starts, and the new rent normally starts on the next rent due date after that period. The tool adds your notice days to the notice date and then finds the next due day you entered.
Rules differ a great deal between places. Some have no cap, some tie increases to inflation and some have rent control or stabilisation limits. Enter the cap that applies to you to see whether an increase is within it, and always check local law and your lease.
Splitting rent between roommates
An equal split is simple, but it can feel unfair when rooms differ. Splitting by room size is a straightforward alternative: someone with a 200 sq ft room pays more than someone with 120. Then adjust for features that matter, such as a private bathroom or a window onto the street, with a premium or discount. The calculator takes the total premiums out of the rent, splits the rest, then adds each person's premium back so the shares always add up to the total.
Shared utilities are divided equally. Write down the agreement, including who is named on the lease and who holds the deposit.
Rent affordability guidelines
- 30% rule. Rent should be no more than about 30% of gross income. Some budgeting guides prefer 25% to 28% in expensive cities, while a cheaper area may allow more.
- 3× rule. Many landlords want monthly income of at least three times the rent.
- 40× rule. A common screen in some cities is yearly income of 40 times the monthly rent.
These are screening tools, not laws. Your debts, savings, transport costs and the utilities included in rent also affect what you can afford.
Tips for tenants and landlords
- Write the proration method into the lease so there is no dispute.
- Keep deposits separate from prorated rent.
- Give and keep written notice of a rent increase with the date.
- Check local rent limits before choosing an increase.
- Agree roommate shares and deposit rules in writing.
Common mistakes
- Counting the wrong number of days, such as leaving out the move-in day.
- Prorating a deposit.
- Using the wrong month length (February versus July).
- Forgetting that notice periods start from when notice is delivered.
- Splitting rent equally without agreeing how room size matters.
Worked examples for each tab
Prorating a move-in. Rent is 2,100 and you move in on the 20th of a 31-day month. Days charged are 12, the daily rate is 67.74 and prorated rent is 812.90. With a 30-day method the daily rate is 70 and the charge is 840. Ask which method the lease uses, because the 27 difference is real money.
Rent increase. A rise from 1,800 to 1,890 is 5%, or 90 a month and 1,080 a year. Repeated each year for five years the rent reaches about 2,297, and you will have paid about 17,300 more than at today's rent. If the landlord gave notice on October 12 with a 60-day period and rent is due on the 1st, the new rent starts on January 1.
Roommates. Three people share 3,000 of rent. Rooms of 200, 150 and 120 square feet pay about 1,277, 957 and 766 before utilities, a spread that an equal split of 1,000 each would ignore.
Affordability. At 5,500 gross a month, 30% is 1,650. A 1,800 rent is 32.7% of income, and the landlord's three-times test needs 5,400, which this household passes.
Moving out mid-month and ending a lease
When a lease ends mid-month, rent is normally due through the last day of occupancy, but the details matter. Some leases require a full month's rent unless proper notice was given, and some count the day the keys are returned. Prorated move-out rent is calculated the same way as a move-in: daily rate multiplied by the days you stay. Keep your written notice and the return date of the keys. If a deposit is held, ask for the itemised deductions in writing, and check how many days your area allows for the deposit to be returned.
Rent changes in the middle of a month
If rent rises or falls part-way through a month, you can prorate each part separately: the old rent for the days before the change and the new rent for the days after. For example, a rise from 1,800 to 1,890 on the 16th of a 30-day month costs 15 days at 60 plus 15 days at 63, which is 1,845 for that month. Run the calculator twice, once for each rent, and add the two parts. Most landlords avoid this by starting a new rent on the first of a month, which is why the increase tab finds the next due date after the notice period.
Privacy
The calculator runs in your browser. The figures you enter are not sent to a server and are not stored. Reloading the page returns the example. Downloaded files are created on your device.
Frequently asked questions
How do you calculate prorated rent?
Divide the monthly rent by the number of days in the month to get a daily rate, then multiply by the number of days you will live there. For example, 1,800 of rent in a 30-day month is 60 a day, so a move-in on the 15th (16 days) is 960.
Which proration method is most common?
Using the actual number of days in the month is the most common method. Some leases use a 30-day month or a 365-day year (monthly rent × 12 ÷ 365). The calculator compares all three so you can see the difference.
Is prorated rent calculated per day?
Yes. Prorated rent is a daily rate multiplied by the days you occupy the home in the partial month. The daily rate depends on the method in your lease.
How do I prorate rent for a move-out date?
Choose move-out, enter the date and the tool charges from the 1st through that date. Some leases count the move-out day and some do not, so check yours.
Do I count the move-in day?
Usually yes: the move-in day is counted as a day of occupancy. This calculator counts it, so moving in on the 15th of a 30-day month gives 16 days.
Should a deposit be prorated?
No. A security deposit is a fixed amount and is not prorated. Pet rent, parking and other recurring monthly charges are often prorated like rent.
What is the first month's total due at move-in?
It is prorated rent plus prorated extras, the security deposit, one-time fees and, if your landlord asks for it, the next full month in advance. Enter each item to see the total.
How much notice is needed for a rent increase?
It depends on where you live and your lease. Common notice periods are 30, 60 or 90 days, and larger increases may need more. This calculator lets you enter the number of days and shows the first rent due date at the new price.
How do I calculate a rent increase percentage?
Subtract the old rent from the new rent, divide by the old rent and multiply by 100. A rise from 1,800 to 1,890 is 90 ÷ 1,800 = 5%.
How much can a landlord raise the rent?
In many places there is no limit apart from the lease. Others have rent control, rent stabilisation or caps linked to inflation. Enter the cap that applies to you to see if an increase is within it.
What does the multi-year table show?
It repeats the same increase each year to show how monthly and yearly rent compound over time and how much more you would pay than at today's rent.
How do you split rent between roommates fairly?
Common ways are equal shares, shares by room size, or size shares adjusted for features such as a private bathroom or the best light. This tool supports equal and size-based splits with premiums and discounts.
What if one room is much bigger?
Choose the by-room-size method. The bigger room pays more in proportion to its square footage, and you can add a premium or discount for features that matter.
How should utilities be shared?
The tool divides shared utilities equally. If one person uses much more, agree on a different split in writing.
What is the 30% rule for rent?
The 30% rule says to spend no more than about 30% of your gross income on rent. It is a guideline, and it may be too high or too low depending on your debts, location and other costs.
What is the 40× rule or 3× rule landlords use?
Many landlords ask for yearly income of 40 times the monthly rent, or monthly income of three times the rent. These are screening rules and vary by landlord.
Can I use this for commercial rent or weekly rent?
The daily proration works for any amount of rent paid monthly. For weekly or fortnightly rent, convert to a monthly figure first or check the lease. Commercial leases often have their own rules.
Can I print or export?
Yes. Print / save as PDF prints only the calculation for the tab you are on, CSV downloads it and copy summary puts it on your clipboard. Nothing is uploaded.
Sources and further reading
- Common residential lease practice for prorating rent by actual days, 30-day months and 365-day years.
- Local landlord-tenant statutes and rent control rules, which differ by jurisdiction and should be checked for notice periods and caps.
- Consumer guidance on the 30% of income guideline for housing costs and landlord income screening.
- Property management industry practice for splitting rent among co-tenants by room size.
Sources were consulted in October 2026. Standards and rules can change, so always check the official page for your situation.