How to Calculate Prorated Rent: Three Methods, Three Different Answers

Your lease starts January 16, rent is $2,100, and the move-in ledger says you owe $1,120 for the rest of January. You ran it on your phone and got $1,083.87. One of you is wrong, or you are both right and using different math, and knowing how to calculate prorated rent yourself is the only way to tell.

That is the whole problem with prorated rent. There is no single formula. Here is how to calculate prorated rent three ways, which one your landlord is probably using, and what to do when the number does not match your lease.

The short answer: prorated rent equals monthly rent divided by the days in the period, times the days you actually occupy. The fight is always over the divisor.

TL;DR

• Three methods exist. Actual days in the month, a flat 30-day month, or yearly rent divided by 365.
• They give different answers. On $2,100 rent for 16 days of January: $1,083.87, $1,120.00, or $1,104.66.
• The lease controls. Look for a prorated rent box or a "partial month" sentence near the rent clause.
• Count the move-in day. January 16 through 31 is 16 days, not 15.
• Move-out has its own rules. Minnesota requires actual calendar days for a final partial month, and the requirement cannot be waived.

The one formula behind every prorated rent number

Every method works the same way:

1. Find a daily rate.
2. Count the days you are responsible for.
3. Multiply.

Only step one changes between methods. Step two is where most honest mistakes happen. If you get the keys on January 16, you owe for the 16th itself, so the count is 31 minus 16, plus 1, which gives 16 days. Forgetting the plus one undercharges by a day. Some landlord software counts from the day after move-in, which also undercharges. Either way, the lease start date decides day one, not the day the moving truck arrives. The difference between those two dates is covered in lease start date vs move-in date.

For all three examples below: rent is $2,100 a month, the lease starts January 16, and you owe 16 days.

Method 1: Actual days in the month

The daily rate is the monthly rent divided by the real number of days in that calendar month.

• Daily rate: $2,100 ÷ 31 = $67.74
• Prorated rent: $67.74 × 16 = $1,083.87

This is the most common method and the one most renters calculate on their own. It is also the method Minnesota writes into law for a final partial month. Its quirk is that the daily rate moves every month. The same apartment costs $67.74 a day in January and $75.00 a day in a 28-day February.

Method 2: The 30-day banker's month

The daily rate is the monthly rent divided by 30, no matter how many days the month has.

• Daily rate: $2,100 ÷ 30 = $70.00
• Prorated rent: $70.00 × 16 = $1,120.00

Landlords like it because the daily rate never changes and the math is easy. In a 31-day month it costs you more. It also creates an odd result: under a strict 30-day method, a January 2 move-in is 30 days at $70, which is the full $2,100, even though you missed a day. In February it flips in your favor. Fourteen days of a 28-day February costs $980 under this method, against $1,050 under actual days.

Method 3: The 365-day year

The daily rate is a full year of rent divided by 365.

• Yearly rent: $2,100 × 12 = $25,200
• Daily rate: $25,200 ÷ 365 = $69.04
• Prorated rent: $69.04 × 16 = $1,104.66

This one is the least common in residential leases but shows up in commercial leases and some property management software. Its rate is the same every day of the year, which makes it the most even-handed of the three. It lands between the other two in a 31-day month and is the cheapest of the three in February.

How to calculate prorated rent for your own move

Put the three side by side, same $2,100 rent:

Scenario	Actual days	30-day month	365-day year
Move in Jan 16, 16 days	$1,083.87	$1,120.00	$1,104.66
Move in Feb 15, 14 days, non-leap year	$1,050.00	$980.00	$966.58
Move out Mar 10, 10 days	$677.42	$700.00	$690.41

The spread is $23 to $83 on these examples. That is not life-changing, but it is exactly the size of gap that shows up on a move-in ledger without explanation. If the landlord's number matches one of the three columns, they are using that method, and the only question is whether your lease allows it. If it matches none of them, something else is going on: a wrong day count, a fee folded in, or a full month billed with a credit promised later.

Where your lease names the method

Most leases settle this in one sentence near the rent clause. A common commercial-style version reads like this:

A typical partial-month clause:

If the Commencement Date is a day other than the first day of a
calendar month, Rent for such partial month shall be prorated on the
basis of a thirty (30) day month and shall be due and payable on the
Commencement Date.

What it means: This lease uses the 30-day method. A January 16 start at $2,100 is $1,120, due the day the lease starts. The landlord's number is correct even though it is not what your phone said.

Apartment-style leases often show it as a fill-in box instead. The Texas Apartment Association lease, the standard form across much of Texas, has a line labeled "Prorated Rent" with a dollar amount and two checkboxes: due for the remainder of the first month, or due with the second month. That form records the amount but does not state a method, so you are checking the landlord's arithmetic, not a formula.

If your lease says nothing at all, actual days in the month is the most widely used default and the easiest one to defend. Ask the landlord which method they used and why. The how to read a lease walkthrough shows where the other money clauses usually sit around this one.

Prorated rent when you move out

Move-out proration follows a different rule: you pay through the date your tenancy legally ends, not the day you hand back keys.

On a fixed-term lease, that is the end date in the lease. Moving out early does not prorate anything, and the options for leaving before that date are in how to break a lease.

On a month-to-month tenancy, it is the end of your notice period. California's Department of Real Estate gives a clean example. A tenant who gives 30 days' notice on September 10 owes rent through October 10, meaning 20 days of September and 10 days of October.

Minnesota goes further and writes the method into statute:

Minnesota Statutes § 504B.116:

When a lease term for a residential unit ends on a date before the
last day of the final month, the amount of rent to be paid for the
final month must be prorated at the average daily rate for that month
so that the tenant only pays for the actual number of days that
occupancy is allowed. ... Any attempted waiver of this section by a
landlord and tenant, by contract or otherwise, shall be void and
unenforceable.

What it means: In Minnesota, a lease ending March 10 at $2,100 costs $677.42 for March, using 31 days, even if the lease says to divide by 30 or to pay the full month. The statute also says it applies when you prepaid last month's rent, so any overpayment should come back to you.

Most states have no statute this specific, which leaves the lease in charge. That is the reason to check the partial-month clause before you sign, not after.

When the landlord's number is wrong

Run the three methods. If the charge matches none of them, or matches a method your lease does not allow, put it in writing:

A short email that gets a corrected ledger:

My lease starts January 16 at $2,100 per month. Section [X] says
partial months are prorated by [actual days / a 30-day month]. That
gives [16] days at [$67.74], or [$1,083.87]. The ledger shows
[$1,120.00]. Please correct the move-in charge or show me the
calculation you used.

What it means: You have named the clause, shown your math, and asked for theirs. Most ledger errors get fixed at this step.

Ask for the correction on the current invoice, not as a future credit. If the landlord refuses and the amount is meaningful, pay under protest in writing and keep the email thread. A charge you disputed at the time is far easier to recover later from the deposit accounting than one you paid without comment. Move-in ledgers also carry the fees described in hidden apartment fees, so check the rest of the bill while you have it open.

Redline reads your lease in plain English. Photograph it, paste it, or upload it, and Redline finds the partial-month clause, names the proration method, and flags move-in or move-out terms that cost you more than the math says. One scan, one dollar. Available on iOS and Android.