What this calculator does
Pro rata rent is the proportional share of a full period rent owed when a tenancy does not start or end exactly on the boundary of that period, most commonly a move-in date partway through a month. Rather than charging a full month for a partial stay, the rent is scaled down to match the actual number of days occupied.
The calculation itself is simple once the two reference numbers are clear: how many days are in the full period being pro rated (a specific month's length, or a standard 30-day convention some leases use), and how many of those days are actually being paid for. Getting the days-in-period figure wrong is the most common source of a wrong pro rata rent figure, since February, a 30-day month and a 31-day month all divide the same rent differently.
The formula
Divide the full period rent by the number of days in that full period to get a daily rate, then multiply the daily rate by the number of days actually occupied. The result is the proportional rent owed for the partial period.
| Term | Meaning |
|---|---|
| Daily rate | Full period rent divided by the days in that period. |
| Days in the full period | The actual number of days in the specific month (or other period) being pro rated, not a fixed assumption. |
| Days occupied | The number of days actually being paid for within that period. |
The inputs explained
| Field | What to enter |
|---|---|
| Full period rent ($) | The rent charged for a full period, such as a full calendar month. |
| Days in the full period (e.g. days in that month) | The number of days in that full period, e.g. 28, 29, 30 or 31 for a calendar month, or 30 if the lease uses a flat 30-day convention. |
| Days actually occupied | The number of days actually occupied within that period, that the pro rata charge covers. |
When to use it
Moving in partway through a month
A tenant starting on the 19th of a 30-day month owes rent for 12 days rather than the full month, worked out as the daily rate multiplied by those 12 days.
Moving out before the end of a period
The same calculation applies to a partial final month: the daily rate multiplied by the number of days actually occupied before vacating.
Checking a landlord or agent's figure
Recomputing pro rata rent independently, using the actual days in that specific month rather than a flat assumption, is a quick way to check a move-in statement or final invoice.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How pro rata rent changes with days occupied, in a 30-day month
A fixed $2,000 monthly rent and a 30-day month, across a range of days occupied.
| Days occupied | Pro rata rent owed | Share of full period |
|---|---|---|
| 5 days | $333.33 | 16.7% |
| 10 days | $666.67 | 33.3% |
| 12 days | $800.00 | 40.0% |
| 15 days | $1,000.00 | 50.0% |
| 20 days | $1,333.33 | 66.7% |
| 25 days | $1,666.67 | 83.3% |
How pro rata rent for the same partial stay changes with the days in that month
A fixed $2,000 monthly rent and 12 days occupied, across the range of days a calendar month can actually have.
| Days in the month | Pro rata rent owed | Daily rate |
|---|---|---|
| 28 days | $857.14 | $71.43 |
| 29 days | $827.59 | $68.97 |
| 30 days | $800.00 | $66.67 |
| 31 days | $774.19 | $64.52 |
Questions
Should I use the actual days in the month or a flat 30-day figure?
Check the lease. Some leases explicitly pro rate using the actual calendar days in that specific month; others use a flat 30-day (or 360-day-year) convention regardless of the real month length. The two can give slightly different figures, so use whichever basis the lease specifies.
Does pro rata rent apply to fees other than base rent?
It depends on the lease and jurisdiction. Some agreements pro rate the base rent only, while others also pro rate parking, utilities or other recurring charges over the same partial period. Check what the lease actually covers.
How is pro rata rent different from a security deposit adjustment?
Pro rata rent is simply the rent owed for a partial period, calculated proportionally. A security deposit is a separate, usually refundable amount held against damage or unpaid rent, and is not adjusted using this same daily-rate calculation.
What if the move-in and move-out dates are both partial?
Run this calculator separately for each partial period using that period's own days-in-month figure and days occupied, then add the two results together for the total rent owed across both partial months.
For the urine-output style rate calculation using the same per-unit logic, see the urine output calculator. For weighing renting against buying over the longer term, see the rent or buy calculator.