How to read this result
In the default example, vacancy rate is 8.22%. Results describe this input scenario; they are not a recommendation.
Change one assumption at a time to see how it affects the scenario. Compare periods and cost definitions consistently. Negative results show a modeled shortfall; an unavailable ratio needs a valid denominator.
Formula and methodology
Choose vacant days divided by available days or vacant units divided by total units. Multiply the selected ratio by 100. Occupancy is the remaining percentage of the same selected physical capacity.
Enter percentages as whole numbers: 5 means 5%. When used as a factor, the calculation divides a percentage by 100. Percentage outputs multiply the final ratio by 100. Calculations retain precision internally; displayed amounts and rates are rounded to two decimals.
Variables and input definitions
- Mode (select)
- Default mode is vacant days; also support unit-based mode.
- Vacant days (days)
- Total unrented days in the analysis period. Minimum: 0. Maximum: 365.
- Available days (days)
- Total rentable days in the same period. Minimum: 1. Maximum: 366.
- Vacant units (units)
- Used only in units mode. Minimum: 0.
- Total units (units)
- Used only in units mode. Minimum: 1.
Worked example
This example uses the exact prefilled inputs above. Reset defaults to restore this scenario after making changes.
| Item | Default scenario |
|---|---|
| Mode | Vacant days |
| Vacant days | 30 |
| Available days | 365 |
| Item | Default scenario |
|---|---|
| Vacancy rate | 8.22% |
| Occupancy rate | 91.78% |
Assumptions and limitations
Physical vacancy and economic vacancy are different concepts; label the selected method clearly.
Results describe this input scenario; they are not a recommendation.
The tool uses values you supply. It does not retrieve market prices, verify leases or inspect a property. Results exclude items outside the listed inputs. Review local requirements and the relevant contract when a payment, fee or allocation depends on them.
Common mistakes
Do not combine a count of vacant units with a count of available days. Physical vacancy also differs from economic vacancy measured in lost rental dollars.
Sources and method references
These references provide context for the method and terminology. They do not endorse this tool or validate your property assumptions.
- IRS — Publication 527 (2025), Residential Rental PropertyRental income and expense concepts; operating/rental expense context.
Frequently asked questions
Why are the unused vacancy fields hidden?
Each mode has its own numerator and denominator. Only the selected day or unit fields affect the calculation, so inactive values cannot invalidate the other mode.
Is this an economic vacancy calculator?
The two supported modes measure physical vacancy. Economic vacancy would compare lost rent with potential rent and can also reflect concessions, nonpayment or below-market rents.