Vacancy Rate Calculator

How to use the vacancy rate calculator

Enter:

• Units: how many rentable units you have.
• Period: the number of days you’re measuring, usually a year (365 days) or a quarter.
• Vacant unit-days: the total days units were empty during that period. If one unit was empty 30 days and another 15, enter 45.
• Monthly rent, if you want the lost-rent figure. Use the average rent if your units differ.

The calculator returns your vacancy rate and the rent lost to vacancy.

The vacancy rate formula

• Total unit-days = units x days in the period
• Vacancy rate = vacant unit-days / total unit-days x 100
• Daily rent = monthly rent x 12 / 365
• Lost rent = vacant unit-days x daily rent

Counting unit-days, rather than counting units that are vacant on one particular day, gives you a fair picture for a small portfolio. One empty unit on the day you check would show a four-unit building as 25% vacant.

A worked example

You own a fourplex. Each unit rents for $1,400. Over the past year, one unit sat empty 30 days between tenants and another sat empty 15 days.

• Total unit-days: 4 x 365 = 1,460
• Vacant unit-days: 30 + 15 = 45
• Vacancy rate: 45 / 1,460 = 3.08%
• Daily rent: $1,400 x 12 / 365 = $46.03
• Lost rent: 45 x $46.03 = about $2,071

Next year, if you cut the 30-day gap to 10 days by listing during the notice period, vacancy falls to 25 unit-days, or 1.71%, and lost rent drops to about $1,151.

What a good vacancy rate looks like

For a small landlord, a good vacancy rate is below what you assumed when you bought the property. If you underwrote at 5% and you’re running at 3%, the property is doing better than planned.

For context, the U.S. Census Bureau put the national rental vacancy rate at 7.3% in the second quarter of 2026. That figure counts every vacant unit for rent, including large apartment buildings in markets with a lot of new supply. A well-run single-family home or small multifamily building with long-term tenants is often well below it, but your local market sets the bar.

If your rate is high, look at the cause:

• Long gaps between tenants: start marketing during the notice period and price to the market.
• Frequent turnover: look at renewal pricing, maintenance response times and screening.
• One problem unit: check its condition and price against similar listings.

Limits and caveats

• Short periods are noisy. One move-out in a two-unit building makes a quarter look terrible. A year is a better measure.
• Unrentable time. Decide whether days spent on a major renovation count as vacancy. Most landlords track them separately.
• Credit loss isn’t included. Rent you’re owed but never collect is a separate loss.
• Rent differences. If your units rent for very different amounts, lost rent from an average rent is an approximation. Calculate each unit separately for an exact figure.