Follow the default numbers.
With monthly rent of $2,400, the model gives vacancy rate: 5%.
The formula is vacant unit-days ÷ available unit-days. Open the breakdown to trace expenses and assumptions. Change one input at a time to see how your decision changes. This example uses scenario inputs; it is not an offer, tax bill, appraisal or legal determination.
Count unit-days, not properties
A four-unit property has four times as many available rental days as one unit. Add the vacant days for each unit, then divide by units multiplied by period length. A unit vacant for thirty days contributes thirty unit-days even if all other units remain rented. Vacancy and occupancy always add to one hundred percent. The lost-rent estimate assumes every unit has the same scheduled rent.
Vacancy is not the same as collection loss
An occupied unit with unpaid rent can have zero physical vacancy and substantial economic loss. Concessions, bad debt and partially occupied months also affect realized revenue. Use this tool for physical vacancy, then include collection losses and concessions in your income model. Do not deduct the same loss once here and again in NOI.
Plan for turnover
Compare the result with the period that matches your decision. A one-month turnover in a twelve-month period has a different annual impact than the same turnover during a three-month report. Seasonal rentals require a realistic availability denominator. Rent that could never have been collected should not inflate the loss estimate. Test longer turnover periods before relying on a tight cash-flow margin.
Keep your assumptions with the result
Save the calculation to your deal file to reuse compatible inputs in another tool. The file stays in this browser on this device. Download the CSV to open the complete inputs, results and schedule in Excel or Google Sheets. Use PDF to print the report or save it as a PDF. A share link includes entered financial figures in its URL, so use it only with people you intend to share those numbers with.