Vacancy Rate: How to Calculate It and What It Tells You

What Is Vacancy Rate?

Vacancy rate is the share of available rental time a unit sits unoccupied, expressed as a percentage. It measures lost income from empty units, which is one of the largest recurring costs of operating a rental property.

There are two related concepts. Physical vacancy is the time a unit is literally empty. Economic vacancy includes rent lost to non-payment, concessions, and the days a unit is listed but not yet leased. Economic vacancy is the figure that belongs in a cash flow analysis, because it captures all the rent you fail to collect.

Vacancy Rate = Vacant Time ÷ Total Available Time

Why Vacancy Rate Matters

Vacancy matters because it is a direct income loss that compounds with turnover costs. A single turnover can cost one to two months of rent plus paint, cleaning, and minor repairs, and owners who model steady-state cash flow get blindsided because year one often has no turnover at all.

Treating vacancy as a recurring expense line, rather than an occasional accident, is what separates an honest cash flow projection from a rosy one. Plan for one turn per unit every two to three years and hold the cost against the reserve.

The Formula and Each Variable

• Vacant Time: the number of days (or months) a unit is unoccupied and not earning rent during the period.
• Total Available Time: the full period the unit could have been rented, typically 365 days or 12 months.

For underwriting, use economic vacancy, which adds non-payment and concessions to physical vacancy. Physical vacancy alone understates the rent you actually lose.

Worked Example: Vacancy Rate

The following hypothetical example shows both a single-unit calculation and how vacancy feeds a cash flow projection. The numbers are illustrative only.

A 5.8% physical vacancy rate becomes a 6.8% economic vacancy rate once non-payment and concessions are included. Use the economic figure in your cash flow analysis so the projection reflects the rent you actually collect.

What a Healthy Vacancy Rate Looks Like

In stable markets, plan for 5–8% economic vacancy. Student and seasonal markets run higher. A property with consistently low vacancy may reflect strong retention, or it may reflect below-market rents that keep tenants in place but leave income on the table.

Compare your vacancy rate to the local market norm. Running well below market may mean your rent is too low; running above market signals a retention, pricing, or property-condition problem worth fixing.

Turnover Costs That Compound Vacancy

Vacancy loss is only part of the cost of an empty unit. Turnover adds make-ready costs that compound the hit.

• Lost rent during the days the unit is listed and empty.
• Paint, cleaning, and minor repairs to make the unit rent-ready.
• Advertising and tenant placement costs, including leasing fees.
• Utilities you pay while the unit is vacant.

Model one turnover per unit every two to three years, and hold the combined vacancy plus make-ready cost against the reserve rather than treating it as a surprise.

Retention Is the Cheapest Vacancy Cure

Renewing a good tenant costs a fraction of replacing one. The cheapest way to reduce vacancy loss is to keep the tenant you already have.

• Respond to maintenance requests quickly; slow responses drive move-outs.
• Renew leases early at fair increases rather than waiting for the lease to expire.
• Do a walkthrough before the renewal decision so small issues get fixed before they become reasons to leave.
• Price renewals at market; below-market rents retain tenants but leave income on the table, while above-market increases trigger turnover.

Using Vacancy Rate in Underwriting

In a cash flow projection, apply a vacancy percentage to gross scheduled income to estimate vacancy loss, then subtract it before operating expenses. Pair the vacancy assumption with break-even occupancy to stress-test the deal: the gap between your assumed vacancy and the break-even occupancy is your margin of safety.

Rerun the deal with vacancy at double your assumption to see whether it survives a soft market. If it only works at the optimistic vacancy figure, you are buying an assumption, not a deal.

Common Mistakes

• Assuming 100% occupancy forever in a cash flow projection.
• Using physical vacancy when economic vacancy is the relevant figure.
• Ignoring turnover costs that compound vacancy loss.
• Setting rent above market, which raises vacancy and can cost more than the extra rent earns.
• Treating low vacancy as success when it actually reflects below-market rent.

Frequently Asked Questions