What the three amounts mean
Actual calendar days: for each month touched by your dates, divide monthly rent by the actual calendar days in that month, multiply by the chargeable days in that month, then add the monthly portions. February therefore uses 28 or 29 as applicable.
30-day month: divide monthly rent by 30 and multiply by all chargeable days. This keeps the daily rate fixed even when a calendar month has a different length.
Annual / 365: convert monthly rent to an assumed annual amount by multiplying by 12, divide by 365, then multiply by chargeable days. This calculator uses 365 as written; it does not switch to 366 in a leap year.
The “difference” is the highest displayed method total minus the lowest displayed method total. Its percentage is that rounded dollar difference divided by monthly rent. These are this page’s calculations, not a statement that one method governs your lease.
February and leap years
Example assumptions: monthly rent is $2,000 and 14 days are chargeable. With a 28-day February, actual-days rent is $2,000 ÷ 28 × 14 = $1,000.00. With a 29-day February and the same 14 chargeable days, it is $2,000 ÷ 29 × 14 = $965.52. The monthly rent and day count are held constant to show only the divisor’s effect.
For the 30-day method, the same assumed rent and 14 days produce $933.33 in either February. For annual / 365, the calculation is $2,000 × 12 ÷ 365 × 14 = $920.55 in either case. Intermediate arithmetic is not rounded; only each final amount is rounded to cents.
Which amount should you use?
There is no single amount that this calculator can identify as legally due everywhere. Check the proration language in your lease and the state or local rule that applies to your specific move-in or move-out. If they do not clearly establish a method, ask the landlord for the written day-count and divisor before relying on a calculator output.
The actual-days method tracks the real length of each calendar month and the dates charged, so its arithmetic maps directly to calendar occupancy. That explains why a tenant or landlord may prefer it for a transparent month-specific calculation; it does not prove that the method is more common, legally required, or controlling in your location. This page does not provide legal advice.
Rent proration questions
How do I calculate prorated rent for a mid-month move-in?
Enter the monthly rent and the first and last chargeable dates, then compare the three displayed methods. The actual-calendar-days method divides rent by each month’s actual calendar days, multiplies by the chargeable days in that month, and adds the monthly portions. Use the method named in your lease or billing terms.
Is the move-in date included in prorated rent?
This calculator counts both selected dates as chargeable. If your lease excludes the move-in date, set the first chargeable day to the following date; if it includes that day, use the move-in date. Check the agreement’s date-count rule.
Can prorated rent be more than one month’s rent?
Yes. A date range can cross a month boundary, and the actual-days total adds the portions for each month. The 30-day calculation can also exceed one monthly rent when it applies more than 30 chargeable days. Check the selected dates and divisor against your lease; a calculator result alone does not establish the amount owed.
What official examples do—and do not—settle
Minnesota Statutes § 504B.116 (2026) addresses a residential lease that ends before the last day of its final month: the final-month rent must be prorated at that month’s average daily rate so the tenant pays only for actual allowed occupancy. The statute says this provision applies even when a lease requires the last month’s rent to be paid in advance. Its subsection (b) specifies the actual calendar days in that expiration month, and says an attempted waiver is void and unenforceable. The section describes that final-month situation; it does not, by its text, prescribe a formula for every move-in. Minnesota Statutes § 504B.146 (2026) separately requires a written lease to state the prorated amount on its first page when it sets a non-first/non-last move date and prorated rent applies. Read these provisions only for the situations they name: one gives a calculation basis for certain lease endings, while the other requires disclosure for specified move dates.
Caltrans Exhibit 11-EX-5, “Rent Proration Examples” (revision 1/2020), instructs that its applicable rent and utility prorations use a 30-day month regardless of the calendar month’s length. It says no proration is needed when a tenancy starts on the first or is vacated on the last day of a month. Its steps include the tenancy start or vacate date in the chargeable-day count and round the final result to the nearest penny without first rounding the daily rate. The exhibit also caps partial-month rent at a full month’s rent. In its March example, a $500 monthly rent and a March 17 start produce a $16.67 daily rate and 15 chargeable days; multiplying those displayed values gives $250.05. In a separate June example, a $500 rent and June 23 start produce eight charged days and $133.36. Its February example uses a $500 rent, a February 25 start, and four charged days to produce $66.68; the exhibit says to use the same procedure in a leap year with 29 days. This is a Caltrans procedure for the situations covered by that exhibit, not proof of a rule for a private residential lease.
SEC-filed Exhibit 10.19 is a lease dated June 2, 2017, between HCP Torreyana, LLC and BioAtla, LLC for office and laboratory premises at 11085 Torreyana Road in San Diego. Section 3.1 sets fractional-month rent at 1/365 of applicable annual rent per day when a rent payment date is not the first of a month or a period is shorter than one month. The same section applies that basis to other payments or adjustments requiring time-based proration. That clause is a term of this filed commercial lease; it does not create a residential default. The same divisor can therefore appear as a narrow statutory rule, an agency procedure, or a negotiated contract term, and those sources do not make one another interchangeable.
Calculation scope
One rent amount and one continuous date range per calculation. Both endpoints count as chargeable days. Actual-days proration splits a range month by month; the other methods apply one daily rate across the full range. No account, fee, upload, saved history, or server calculation is used. The comparison cannot interpret a lease, decide whether a move-out day is owed, or apply a local legal rule for you. This tool prorates one rent amount over dates; it does not split rent by room, by area, or by income.
For the rule and lease questions behind partial-month rent, see How to Calculate Prorated Rent. To divide ongoing housing costs among roommates, use the rent split calculator.