How it works
How this tool works.
Most landlords remember a vacancy as an event — “the unit sat empty in March.” A vacancy rate turns those events into a number you can track year over year: of all the time the space was available to rent, what share of it was actually empty? It’s the difference between a vague sense that turnover was rough and knowing your building ran at 6% vacancy last year versus 3% the year before.
This calculator works two ways. For a single unit, enter the days vacant and the period you’re measuring (a year, a quarter, any stretch). For a small portfolio, count in unit-months: four units over twelve months is 48 unit-months of availability, and each month a unit sat empty adds one to the vacant count. Either way the output is your physical vacancy rate and its flip side, your occupancy rate — computed from your records, not compared to anyone else’s.
Pick a mode: one unit measured in days, or a portfolio measured in unit-months.
For a unit, set the days vacant and the length of the period you’re measuring. For a portfolio, set the unit count, the months in the period, and the total vacant unit-months across all units.
The tool divides vacant time by available time: days vacant ÷ days available, or vacant unit-months ÷ total unit-months, and shows the occupancy rate alongside.
Track the number over time — the same calculation run on last year and this year tells you whether your turnovers are getting faster or slower.
Make the result useful
Vacancy-rate measurement
Available units or days define the denominator and must match the reporting period.
Vacant units or days are the numerator; distinguish a point-in-time count from a period total.
Physical vacancy does not automatically capture unpaid or discounted rent.
Use the rate with lost-rent dollars and turnover timing for operational decisions.
The assumptions that move this result
Vacant units/days
Vacancy count for the chosen period.
Available units/days
Total inventory for that same period.
Period
Point-in-time or matching reporting period.
Basis
Physical versus economic vacancy definition.
vacancy rate = vacant inventory ÷ available inventory
Use the output as a documented scenario result, not a guarantee.
Read the number in context
Worked scenario
Scenario: 1 vacant unit ÷ 10 units = 10%.
Edge case
Edge case: a small portfolio can swing sharply from one vacancy.
Does not predict lease-up or quantify all economic loss.
Before you act
• Use a consistent denominator.
• Track days and dollars beside percent.
• Separate unpaid rent from physical vacancy.
Worked formula
vacancy rate = vacant inventory ÷ available inventory
Is this a forecast?
No. It calculates the assumptions you enter.
Can it replace professional review?
No. Use current records and qualified advice.
What should I save?
Keep the assumptions and source records used for the decision.