Prorated Rent Calculator

What is a prorated rent calculator?

A prorated rent calculator finds the dollar amount owed for a partial month at the same effective rate as the monthly rent. It is the standard math for moving in or out partway through a month, for short partial-month periods, and for any other case where the time billed is less than a full calendar month.

How the prorated rent calculator works

Pick a mode and enter the values:

• Move-in proration: enter the move-in date. The calculator counts days from that date through the end of the month (inclusive both ends).
• Move-out proration: enter the move-out date. The calculator counts days from the first of the month through that date (inclusive both ends).
• Custom date range: enter a start date and an end date. The calculator counts every day in between, inclusive of both ends.
• Method: actual days in the billing month, or a flat 30-day month.

Prorated rent formula

The formula has two parts. First, compute a daily rate: daily rent = monthly rent / days. Second, multiply by the number of billable days: prorated rent = daily rent × billable days.

The days denominator depends on the method. The actual-days method uses the real number of days in the billing month: 28 in February of a non-leap year, 29 in February of a leap year, 30 in months like April or November, and 31 in months like March or July. The 30-day method uses a flat 30 for every month.

Move-in proration

When you move in mid-month, the first month bills only the days from the move-in date through the end of the month. With a monthly rent of $2,000 and a move-in date of March 15:

• Days in March: 31. Daily rent = $2,000 / 31 ≈ $64.52.
• Billable days from March 15 through March 31, inclusive = 17.
• Prorated rent = $64.52 × 17 ≈ $1,096.77.

Move-out proration

When you move out mid-month, the last month bills only the days from the first of the month through the move-out date. With $2,400 monthly rent and a move-out date of April 10:

• Days in April: 30. Daily rent = $2,400 / 30 = $80.
• Billable days from April 1 through April 10, inclusive = 10.
• Prorated rent = $80 × 10 = $800.

Actual-days method vs 30-day method

The two common denominators produce slightly different daily rates. With $2,000 monthly rent in March:

• Actual-days method: $2,000 / 31 ≈ $64.52 per day.
• 30-day method: $2,000 / 30 ≈ $66.67 per day.

For a 17-day move-in proration in March, the methods produce roughly $1,096.77 (actual) versus $1,133.33 (30-day). Check your lease for the agreed-upon method; if the lease is silent, the actual-days method is the more common residential default.

Date and counting conventions

• Move-in date is inclusive. The move-in date itself counts as a billable day.
• Move-out date is inclusive. The move-out date counts as a billable day in the move-out month.
• Custom ranges are inclusive on both ends. Both the start date and the end date count.
• Local calendar math only. The calculator parses each date as a plain calendar date (year, month, day) and computes the day difference directly, so daylight saving transitions and timezone offsets cannot shift the answer.
• Leap years handled. February has 29 days in a leap year and 28 days otherwise; the actual-days method picks this up automatically.

Worked examples

• Move-in March 15, $2,000/mo, actual days: 17 billable days at $64.52/day ≈ $1,096.77.
• Move-out April 10, $2,400/mo, actual days: 10 billable days at $80/day = $800.
• 30-day method, move-in March 15, $2,000/mo: 17 billable days at $66.67/day ≈ $1,133.33.
• Custom range March 15 to March 20, $2,000/mo, actual days: 6 billable days at $64.52/day ≈ $387.10.
• February leap year, move-in February 20, $1,800/mo, actual days: 29 days in February. Daily rent ≈ $62.07. 10 billable days = $620.69.

Common mistakes

• Forgetting that the move-in or move-out date counts. Some leases use exclusive end dates; if yours does, the billable day count drops by one.
• Using the wrong denominator. February with 28 days produces a higher daily rate than March with 31 days, even for the same monthly rent.
• Mixing methods within one calculation. Use either actual days or the 30-day method consistently.
• Forgetting leap year. February has 29 days in 2024, 2028, 2032, and so on; the actual-days method accounts for that automatically.
• Treating prorated rent as a separate negotiated number. It is a math result from the monthly rent and the dates; disputes are usually about which dates or method applies, not about the multiplication itself.

When prorated rent shows up

The two most common cases are moving into a new place partway through a month and moving out before the end of the lease. Less common cases include a lease that starts or ends on an unusual day, a roommate change mid-month, or a short-term arrangement priced at a monthly rate but billed for a partial period.

For other rent and money math, see the savings calculator for setting aside money toward rent, the date calculator for counting days between any two dates, and the percentage calculator for the related percent math (such as figuring out what fraction of a full month a prorated period represents).

Related tools

• Rent split calculator for dividing rent and utilities between roommates by even, income, room size, or custom percentage.
• Rent increase calculator for the math behind a rent change: new rent, percentage change, or annual cost.
• Date calculator for counting days between any two dates.
• Savings calculator for projecting how to save toward a rent or deposit goal.
• Percentage calculator for the three standard percent calculations.
• All money calculators.