How to Estimate Vacancy Rate on a Rental Property Before You Buy It

National rental vacancy hit 7.3% in Q1 2026 (U.S. Census Bureau) — roughly one lost month of rent per year on average. If your pro forma still assumes 5% or zero, you're probably not buying the deal you modeled. This post walks through how to estimate the vacancy rate on a rental property before you close.

A property "cash flows $300/month." You run the numbers, the deal looks tight but workable, you sign the contract. Twelve months in, your tenant moves out, the unit sits empty for six weeks, and suddenly you've eaten your entire year's profit in turnover and lost rent. That's the most common way a "good deal" turns into a bad one — and almost every post-mortem traces back to vacancy being ignored or guessed at.

The regional spread matters as much as the national number: the South ran 9.0% in Q2 2025 while the Northeast sat at 5.2%. Plugging in a stale 5% rule of thumb in a 9% market isn't conservative — it's optimistic.

For the full income-and-expense workflow vacancy plugs into, start with how to analyze a rental property.

What Is Vacancy Rate — and What It Actually Costs You

Vacancy rate is the percentage of time a rental unit sits unoccupied and isn't producing income. For a single property, it's calculated over the year.

The reason vacancy matters more than almost any other expense line: it scales with your rent. A 1% interest rate swing changes your mortgage payment by a fixed dollar amount. A 5% jump in vacancy assumption wipes out 5% of your gross income — which, at thin margins, is often 100% of your cash flow.

Most rental property calculators include a vacancy line. Will It Flow includes it by default and lets you stress-test it against income — because the gap between "5% vacancy" and "10% vacancy" is the single biggest reason a deal that pencils on paper underperforms in real life.

What the National Numbers Actually Look Like in 2026

If you've read any blog post telling you to "just use 5% for vacancy," that number is roughly two years stale. Here's what the Census Bureau's Q1 2026 Housing Vacancy Survey actually shows:

• National rental vacancy rate: 7.3% (Q1 2026)
• Principal cities: 7.8%
• Suburbs: 7.1%
• Outside metropolitan areas: 5.4%

And by region (Q2 2025, most recent regional breakdown from Census Bureau data):

• South: 9.0% — highest in the country
• Midwest: 6.6%
• West: 5.7%
• Northeast: 5.2%

Three forces are driving the climb back up:

1. New multifamily supply. Construction completions from the 2021–2022 building boom hit the market in 2024–2025, loosening tight rental markets — especially across the Sun Belt.
2. Elevated mortgage rates. When rates rose, fewer renters became buyers — which sounds good for landlords, but the trade-off was overbuilding in markets that expected continued tightness.
3. Migration unwinding. The pandemic-era surge into Sun Belt metros has cooled, and markets like Austin, Phoenix, and Tampa are now seeing the highest vacancy increases.

If you're underwriting a deal in the South, plugging in 5% vacancy is no longer conservative — it's optimistic.

The Mistakes Beginners Make Estimating Vacancy

There are three patterns that wreck a pro forma.

Mistake 1: Using the seller's vacancy number. The seller's "current vacancy" is almost always 0% — because the unit is occupied right now, and they want it to look good on paper. That tells you nothing about what your vacancy will be after the current tenant turns over, which they often do within 12 months of a sale.

Mistake 2: Using a national average for a local market. The national number (7.3%) hides huge regional spreads. The South is at 9.0%. The Northeast is at 5.2%. Even within a single metro, Class A apartments can run 10% vacancy while a Class B duplex two miles away runs 4%. National averages are a starting point, not an answer.

Mistake 3: Forgetting that vacancy isn't just turnover days. Real vacancy includes the days between tenants (~14–30 days for an average single-family rental), plus any time spent on rent-ready repairs, plus the occasional non-paying tenant who takes weeks to remove. A "5% vacancy assumption" needs to cover all of that, not just the listing-to-lease gap.

This is the single most actionable visual you can run on a deal — see how a $1,800/month rental that cash flows $300 at 0% vacancy can turn negative at 10%. You can stress-test this yourself with Will It Flow's rental property calculator by flexing the vacancy slider on any deal.

How to Actually Estimate Vacancy Rate on a Property You Haven't Bought Yet

Here's the workflow if you're underwriting a deal in the next 30 days.

Step 1: Pull the metro-level vacancy rate. The U.S. Census Bureau publishes quarterly vacancy data for the 75 largest metropolitan statistical areas. That's your floor. If you're in Houston, your starting number is the Houston-specific rate — not the national one.

Step 2: Adjust for location within the metro. The Q1 2026 Census release breaks vacancy down further: principal cities ran 7.8%, suburbs ran 7.1%, and areas outside metropolitan statistical areas ran 5.4%. If you're buying in a principal city, your starting number is higher than the metro average; in a rural area outside any MSA, it's lower. Property class and asset type also matter — older Class C properties tend to turn over more often than Class B single-family rentals — but those are directional adjustments to apply with judgment, not published averages.

Step 3: Adjust for property-specific risk factors. Bump your assumption up if any of these are true:

• The property has had 3+ tenants in the last 5 years (high turnover signal)
• The neighborhood has new competing supply coming online
• The unit needs cosmetic work that will extend your first lease-up
• Rent is being marketed at the top of the local range (harder to lease)

Step 4: Stress-test it. Run the deal at your base assumption, then again at +3% and +5%. If the deal still cash flows at the higher assumption, you've found something durable. If it doesn't, you haven't built in enough margin.

What a Realistic Vacancy Assumption Looks Like in 2026

There isn't a single right number, but you can build a defensible one from published data. Start with your regional vacancy rate, then apply the location adjustment Census already measures.

Then apply the location adjustment from the Q1 2026 Census release. Principal cities ran 0.5 pp above the national rate (7.8% vs. 7.3%). Suburbs ran roughly at the national rate (7.1%). Areas outside metropolitan statistical areas ran 1.9 pp below (5.4%). If you're underwriting a suburban Houston duplex, your baseline is the South number (9.0%); if you're underwriting a rural Tennessee single-family, you'd subtract roughly 1.9 pp from the regional figure.

From there, judgment takes over. Property condition, asset class, tenant turnover history, and competing supply all push your number up or down — but those are deal-specific adjustments, not published averages, and that's why the stress test in Step 4 matters more than chasing a precise starting figure.

What matters more than the exact percentage: whether your deal still cash flows when you bump the assumption. A property that flows at 5% but breaks even at 8% is not a strong deal — it's a fragile one.

When you run a deal through Will It Flow, vacancy is built into the monthly cash flow calculation automatically, and you can flex the rate to see how the verdict ("It Flows / Neutral / Doesn't Flow") changes.

The Honest Takeaway

Vacancy is the most underestimated expense in beginner rental underwriting. In 2026 — with national vacancy at 7.3% and Southern markets at 9.0% — the old rules of thumb (3%, 5%) are too low for most deals.

The fix isn't complicated. Pull the local metro number, adjust for property class and risk factors, stress-test at +3% and +5%, and require the deal to still cash flow at the higher assumption. Will It Flow handles the math on every deal you run — but the assumption is yours to make.

If your deal only works at 0% vacancy, it doesn't work.

Run Your Numbers With a Realistic Vacancy Assumption

Will It Flow is built for exactly this workflow. Enter your property details, income, expenses, and financing in one place — get instant monthly cash flow, Cap Rate, DSCR, and Cash-on-Cash Return with vacancy baked into every figure. Flex the vacancy slider to see how durable the deal really is.

Open Will It Flow Calculator →

Related Reading

• How to Analyze a Rental Property Before You Buy — The five-step workflow where vacancy feeds into effective gross income and every downstream metric.
• Rental Property Analysis Checklist — A one-page pre-offer screen that includes vacancy in the income and expense lines so nothing gets skipped.
• Is the 1% Rule Still Relevant in 2026? — Why passing a rent-to-price screen still isn't enough if your vacancy assumption is two years stale.
• Best States for Rental Property Investors in 2026 — Regional market context that pairs with Census vacancy data when you're comparing where to buy.