Vacancy rate is the percentage of a rental property's gross potential income that is lost to unoccupied periods — time between tenants, slow lease-ups, or extended vacancies due to market softness or property condition. It is a critical input in any rental property analysis because overestimating occupancy is one of the most common ways investors overpay for properties and underperform expectations.
How Vacancy Rate Affects Cash Flow Analysis
Effective Gross Income = Gross Scheduled Income × (1 − Vacancy Rate)
If a property has a gross scheduled rent of $2,400/month and you apply a 7% vacancy rate, your effective gross income drops to $2,232/month — a $168/month reduction that flows directly to the bottom line. On a leveraged property with thin cash flow margins, a 7–10% vacancy assumption can be the difference between a cash-flowing deal and a break-even or negative one. Always model vacancy conservatively before making an offer, using the Rental Cash Flow Calculator to stress-test different scenarios.
National Average Vacancy Rates
The US Census Bureau tracks residential vacancy rates nationally. Historically, the national average for rental housing has hovered around 6–7%, though this varies significantly by market cycle and property type. During tight rental markets (high demand, low supply), vacancy rates can fall to 2–4% in certain metros. During softer periods or in overbuilt markets, rates can climb above 10%. Your local market vacancy rate matters far more than the national average — check your city's apartment association or real estate data providers for current local figures.
Vacancy vs Credit Loss
Vacancy (physical vacancy) and credit loss (economic vacancy) are related but distinct concepts. Physical vacancy is lost income from empty units. Credit loss is income lost from tenants who are present but not paying — whether due to eviction proceedings, partial payments, or written-off bad debt. In institutional underwriting, both are tracked separately. For individual investors, a combined vacancy and credit loss factor of 5–10% is the typical underwriting assumption. Markets with strong tenant protections (longer eviction timelines) warrant a higher credit loss assumption.
Vacancy's Impact on Yield and Break-Even
Every percentage point of vacancy directly reduces your net rental yield and cash-on-cash return. A property underwritten at 5% vacancy that consistently runs at 10% vacancy will deliver meaningfully lower actual returns than projected. Use the Rental Yield Calculator to model yield at different vacancy assumptions, and the Break-Even Rent Calculator to determine the minimum rent needed to cover all costs — including a realistic vacancy buffer — before committing to a purchase.