Prorated Rent Calculator

What is prorated rent?

Prorated rent is the rent a tenant owes for part of a month instead of all of it. It comes up at both ends of a tenancy: a move-in that lands after the 1st, and a move-out that lands before the last day of the month. In both cases the tenant occupied the unit for only some of the days, so charging a full month would overcharge one side of the deal.

The word prorated means divided in proportion to time. Rent is quoted for a month, so prorating it means carving out the days that actually happened and charging only for those. A tenant who moves in on the 10th of a 30-day month pays for 21 days; a tenant who moves out on the 20th pays for 20. Both are the same arithmetic pointed in opposite directions.

It is a fairness convention before it is a legal rule. There is no single federal formula and most states leave the method to the lease, which is exactly why the same move can produce two different answers: the divisor changes, and the divisor changes the rent. The calculator above solves all three common divisors at once so the gap is visible instead of hidden.

Landlords benefit as much as tenants. A unit that can be rented mid-month stops losing vacancy days the moment the last tenant leaves, and pricing the partial month correctly is what makes that possible without a dispute at the first payment.

The prorated rent formula

Prorated rent = (monthly rent ÷ days in the billing basis) × days occupied. The first division turns a month into a day; the multiplication turns the days back into money. Every method below is that one formula with a different number in the denominator.

The three divisors in common use are the actual length of the move month, a flat 30 days, and the 365-day year. A 31-day month makes each day slightly cheaper than a 30-day one, so the same date can cost a few dollars less under the calendar method than under a flat 30. That difference is small per month and real across a portfolio.

Days occupied is inclusive of the move day. Moving in on the 10th of a 31-day month means days 10 through 31, which is 22 days, not 21. Moving out on the 25th of a 30-day month means days 1 through 25, which is 25 days. The off-by-one is the most common mistake in a hand calculation, and the reason a calculator that counts both ends is worth using.

The page keeps all three methods in view because the right answer is whichever one your lease names. If the lease is silent, the calendar method is the most defensible, because it charges exactly the days in the month being billed rather than a stand-in for it.

Worked example: moving in mid-month

A tenant signs for $1,800 a month and moves in on August 10. August has 31 days, so under the calendar method the daily rate is $1,800 ÷ 31, or $58.06. The move-in day counts, so the tenant occupies days 10 through 31, which is 22 days. Multiply: $58.06 × 22 = $1,277.42. That is the prorated rent for the first month, and it is the figure this page opens on.

Switch the method and the answer moves. Under the 30-day method the daily rate is $1,800 ÷ 30, or $60.00, and 22 days come to $1,320.00. Under the 365-day method the daily rate is ($1,800 × 12) ÷ 365, or $59.18, and the same 22 days come to $1,301.92. The date never changed; only the divisor did.

Read the spread: $42.58 between the cheapest and dearest method on a single month. That is the whole argument for naming the method in the lease. Two people can both be right about the same move and land $43 apart, and neither is doing the math wrong.

The rest of the move-in bill is added on top, not prorated. A $1,800 security deposit and a $200 pet fee are flat amounts, so the total due at move-in is $1,277.42 + $1,800 + $200, or $3,277.42. The calculator carries that total on its own strip when the direction is set to move-in.

Worked example: moving out mid-month

A tenant on the same $1,800 rent moves out on September 25. September has 30 days, and the tenant occupies days 1 through 25, so 25 days are charged. The calendar daily rate is $1,800 ÷ 30, or $60.00, and the final month comes to $1,500.00.

The direction matters because it decides which end of the month is counted. A move-in counts from the move day to the end; a move-out counts from the 1st to the move day. On the 25th of a 30-day month the tenant pays for 25 days and the landlord keeps the unit for the remaining five, which is usually the window in which it is cleaned and re-let.

On this example the 30-day and calendar methods agree, because September has exactly 30 days. Run the same move-out in a 31-day month and they part: the calendar daily rate falls to $58.06 while the 30-day rate stays at $60.00, and 25 days come to $1,451.61 against $1,500.00. The month length is the variable, not the tenant.

One caution worth stating plainly: prorating a move-out is standard at the natural end of a lease, but when a tenant breaks a lease early the prorated figure may be the least of what is owed. Check the lease for a buyout, an early-termination fee, or a requirement to pay until a replacement tenant is found before treating the partial month as the full bill.

Is prorated rent based on 30 days or 31 days?

It depends on the method your lease names, and all three are common. The calendar method divides by the real length of the month being billed, so a July move-in uses 31 and a September move-in uses 30. The 30-day method holds the divisor at 30 no matter the month. The 365-day method spreads the annual rent over the year and uses 365 for every month.

The 30-day method is popular with landlords because it is simple and stable: the daily rate never moves between months, so a schedule of charges is easy to build. The calendar method is popular with tenants because it charges for the month that was actually billed rather than a rounded stand-in. Neither is more correct in the abstract; the lease decides.

The table below runs the same move-in through all three, so the spread is concrete rather than theoretical.

Same rent, same date, three divisors. The example is $1,800 a month moving in on the 10th of a 31-day month, so 22 days are charged and only the divisor changes between the rows.

The difference column is measured against the cheapest method. Name the method in the lease and the argument never happens.

How to prorate the first month’s rent

Find the move-in date, count the days from that date through the end of the month including the move-in day itself, and multiply those days by the daily rate from the method in the lease. That single line is the whole calculation, and the page above runs it live as the date changes.

Collect the prorated first month with the rest of the move-in money. The security deposit, pet fee, parking, and any other one-time charges are flat, not prorated, so they are added to the partial month rather than divided by it. On the $1,800 example those extras are $2,000 and they do not change with the move date, which is why the total due at move-in moves by far less than the rent line does.

Decide when the first full month starts. The usual convention is that the partial month is billed at move-in and the next full month is billed on its own first day, so the tenant pays a small month followed by a full one. Some leases instead roll the prorated amount into the first full month’s payment; either is fine as long as the lease says which.

If a concession is in play, apply it to the partial month before collecting, not after. A “first month free” offer usually means the prorated amount is waived as well, and a “six weeks free” offer is handled in its own section below.

How to prorate the last month’s rent on move-out

Count the days from the 1st of the final month through the move-out day, including the move-out day, and multiply by the daily rate. Moving out on the 20th of a 30-day month means 20 days of rent, not 19, and not a full month.

Prorating the final month is standard when a fixed lease ends mid-month or a month-to-month tenancy ends on a date other than the last day. It is less automatic when a tenant breaks a lease early. In that case the lease may require rent through the end of the notice period, through the end of the term, or until a replacement tenant is found, and the prorated partial month is only one line inside a larger settlement.

Keep the deposit separate from the rent math. The security deposit is held, not earned, so it is returned or applied to damages under the lease and local rules, and it is not the same thing as the last month’s rent. Mixing the two is how a move-out accounting argument starts.

The same three methods apply to a move-out as to a move-in, and the same rule holds: whatever the lease names is the answer. If it names nothing, the calendar method is the defensible default because it charges the actual days of the actual month.

Prorating when rent is due on a day other than the 1st

A lease can start mid-cycle with a billing date that is not the 1st. If rent is due on the 15th, the first “month” runs from the 15th to the 14th of the next month, and a move-in on the 20th means only the days from the 20th to the 14th belong to that first cycle.

The arithmetic is unchanged, only the window is. Count the occupancy days inside the billing cycle, multiply by the daily rate, and that is the prorated amount. The calculator here models the calendar month, which is the overwhelming majority of leases; for an off-cycle billing date, count the days between the start date and the next due date and apply the same daily rate.

The practical advice is to write the billing cycle into the lease explicitly: the day rent is due, what the first partial cycle covers, and which method sets the daily rate. A billing date other than the 1st is where most proration disputes actually start, because two people can disagree about which month is being billed before they ever argue about the divisor.

Free rent and concessions: how “six weeks free” works

A free-rent concession is rent the landlord agrees not to collect, usually to fill a unit faster than the market would on price alone. Six weeks free is about 42 days, and it is applied in one of two ways, which is why two people can read the same offer differently.

The first way is a headline month: the first month and part of the second are free, and the tenant pays nothing until the concession runs out. The second way is an amortized concession: the value of the free weeks is spread across the whole term, so the effective monthly rent is lower than the face rent for every month. A $2,000 rent with six weeks free is worth about $2,308, which amortized across a 12-month lease is roughly $192 a month off.

For a partial month the concession interacts with the proration, and the order matters. Waive the free days first, then prorate the remaining days, or prorate first and then apply the concession, and check which your lease intends. The free-rent field in this calculator takes whole days off the partial month before the rent is figured, which matches the headline-month reading.

Read the fine print on any concession. Many are conditioned on paying on time, staying the full term, or not breaking the lease, and a broken condition can turn the free rent into a balance due. A concession is a discount with strings, not a gift.

Do landlords have to prorate rent?

Often, but not always, and the answer usually lives in the lease rather than in a single law. Prorating at the natural end of a fixed term, when the lease ends mid-month, is near-universal practice. Prorating when a tenant breaks a lease early is frequently not required, because the tenant owes for the term they agreed to, not for the days they chose to stay.

That is why the lease is the first place to look and the local housing authority is the second. Some jurisdictions have statutes or ordinances that speak to proration directly, and a few set a method. Most leave it to the agreement, which means a well-drafted lease ends the question before it starts.

Write three things into the lease: the method (calendar, 30-day, or 365-day), when the prorated amount is due, and how a mid-lease termination is settled. Those three lines remove almost every proration dispute, because each one pins down a number that would otherwise be negotiable at the worst possible moment.

This page is educational, not legal advice. Local rules vary and change, so confirm the specifics for your state and city before you rely on any single method, and have a lawyer review the lease if the stakes are large.

How these numbers are calculated

Prorated rent = (monthly rent ÷ the billing basis) × days occupied. The calendar method divides by the real length of the move month, read from the calendar so leap years are handled; the 30-day method divides by 30; the 365-day method divides annual rent by 365. Days occupied counts both the first and the last day of occupancy, so a move-in on the 10th of a 31-day month is 22 days.

Money is shown to the cent, because rents and daily rates are quoted that way. Free-rent days are subtracted from the occupancy days before the rent is figured, never from the dollars after. The move-in total adds the security deposit and any other one-time costs to the prorated rent; those extras are flat and are never divided by the month.

The comparison table shows all three methods on the same date, and the month curve plots the prorated rent for every day of the move month, so the shape of the discount is visible at a glance. Everything runs in your browser: no input is sent anywhere, and the saved comparisons live in local storage on your own device.

Which calculator to use next

Prorated rent settles one month. If the question is what a property earns over a whole hold, the rental cash flow calculator projects every year of rent, the mortgage, and the sale in one pass. That is the landlord’s version of the same rent figure, carried out over a decade instead of a fortnight.

If the question is whether the rent covers the price at all, the 1% rule is the one-line screen and the cap rate calculator is the fuller answer: what the building earns per dollar of its price, before any loan. Both start from the same monthly rent this page prorates, so the numbers move together.

And if the concern is whether a lender will finance the property, the DSCR calculator runs the coverage test that decides it. Rent is the numerator in all of them, which is why getting the rent right, including its partial months, is the first step rather than a footnote.