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"The seller's pro forma said $78,000 a year. The actual revenue after we bought it was $41,000. We trusted someone else's numbers instead of building our own."
That quote comes from a forum member who lost money on a lakefront cabin in 2023. It is not an unusual story. STR investing has a higher upside than long-term rentals, but it also has more ways to fail, and most of them happen during underwriting, before you ever sign a contract.
This guide walks through how to underwrite a short-term rental from scratch. You will learn how to estimate revenue without trusting seller projections, how to build an expense stack that includes costs most beginners miss, and how to stress-test a deal so you know exactly how bad things have to get before you lose money.
By the end, you will have a repeatable framework you can run on any STR deal in any market.
1Why STR Underwriting Is Different
Long-term rental analysis is relatively straightforward. You collect a fixed monthly rent, subtract predictable expenses, and calculate your net operating income. The variables are mostly stable.
STR analysis has four layers of complexity that long-term rentals do not:
Revenue is variable by definition
A long-term rental earns $1,800/month in January and $1,800/month in August. An STR might earn $6,400 in July and $1,100 in January depending on the market. Projecting annual revenue requires understanding seasonality, not just average daily rates.
The expense stack is deeper
Platform fees, cleaning costs, supply replenishment, professional photography amortization, dynamic pricing software, and higher insurance all add up to an operating expense ratio of 35 to 55 percent of gross revenue for a well-run STR. Long-term rentals typically run 35 to 45 percent. The margin for error is smaller.
Regulations can change your numbers overnight
A city can pass an STR ordinance that requires a permit cap, bans non-owner-occupied listings, or restricts minimum stay lengths. A property that cash-flows at 65% occupancy as a nightly rental might cash-flow at negative $800/month as a long-term rental if the rules change.
Seller projections are almost always wrong
Many sellers list an STR after one good summer and project that peak performance forward as annual income. Others use the platform's built-in revenue estimator, which is notoriously optimistic. Your job is to build independent revenue projections using third-party market data.
2Step 1: Estimating Gross Revenue
Gross revenue is the total amount guests pay before any expenses. Your two inputs are average daily rate (ADR) and occupancy rate. The formula is simple:
// STR Gross Revenue Formula
Gross Revenue = ADR x Occupancy Rate x 365
Example: $220 ADR x 62% occupancy x 365 = $49,753/yr
Where to get real market data:
| Tool | What It Shows | Cost | Best For |
|---|---|---|---|
| AirDNA | ADR, occupancy, RevPAR, market score by zip code and bedroom count | $40–$80/mo | Primary underwriting research |
| Rabbu | Free STR data by market, comp set analysis | Free tier available | Quick market scan before going deeper |
| Mashvisor | Investment metrics layered on MLS listings | $74–$149/mo | Finding on-market STR candidates |
| STR Insight | Hyper-local comp data, forward-looking calendar occupancy | $49/mo | Validating specific property comps |
| Manual Airbnb comps | Pull 6–10 comparable active listings and check their calendars | Free | Ground-truth check on any data source |
⚠️ Always build three scenarios
Never underwrite to a single revenue number. Build a conservative case (10% below market ADR, 5% below market occupancy), a base case (market ADR, market occupancy), and an optimistic case (5% above market ADR, 5% above market occupancy). Your offer should work in the conservative case.
Do not forget platform fees on the revenue side:
Airbnb charges hosts approximately 3% of the booking subtotal. VRBO charges 8%. These come off the top before you see a dollar. If you list on both platforms, weight your blended fee based on your expected booking mix. Most STR operators generate 70 to 85 percent of bookings through Airbnb, with VRBO and direct bookings filling the rest.
Effective Gross Income (EGI) Calculation
Gross Revenue: $49,753
Less Airbnb fees (3%): -$1,493
Less VRBO fees (8% x 15% of bookings): -$597
Effective Gross Income: $47,663
3Step 2: Building the Full Expense Stack
This is where most beginner STR underwriting falls apart. The expenses are more numerous and more variable than long-term rental expenses. Below is every cost category you need to account for, with realistic ranges.
Mortgage (PITI)
Depends on purchase price and down paymentFor a non-owner-occupied investment property, expect 7.5–8.5% rates in 2026 on a 30-year fixed. Use 25% down as your baseline assumption.
⚠️ Property Management / Co-Host Fee
18–30% of gross revenueIf you are not self-managing, this is often the single largest expense after the mortgage. Local co-hosts typically charge 20–25%. Full-service remote management companies charge 25–30%.
Cleaning Costs
$80–$250 per turnoverCleaning cost depends on property size and market. Budget by multiplying your cleaning fee by projected annual turnovers. A 3BR at 62% occupancy with an average 3-night stay generates roughly 75 turnovers per year. At $130/clean, that is $9,750 annually.
⚠️ STR Insurance
1.5–3x the cost of standard homeowner's insuranceStandard homeowner's policies exclude STR activity. You need a specialized policy. Providers include CBIZ, Proper Insurance, and Steadily. Budget $2,500–$6,000 per year for a single-family STR depending on location and property value.
Utilities
$250–$600/monthYou pay all utilities — electric, water, gas, internet, and often streaming services. Guests use more electricity and water than long-term tenants. Budget conservatively, especially for properties with pools or hot tubs.
Supplies and Consumables
$100–$250/monthToiletries, paper goods, coffee, cleaning supplies, batteries, light bulbs, and similar items. Easy to underestimate. Most experienced STR operators budget 2–3% of gross revenue for consumables.
Maintenance and Repairs
1–2% of property value per yearSTRs have more wear and tear than long-term rentals due to higher turnover. Budget at the higher end of the standard 1% rule for STRs. A $400,000 property should carry a $6,000–$8,000 annual maintenance reserve.
⚠️ Furnishing Replacement Reserve
3–5% of gross revenueFurniture, linens, small appliances, and decor wear out faster than you expect. Budget a monthly reserve so replacements don't come as a cash surprise. Couches, mattresses, and outdoor furniture are the biggest recurring costs.
Dynamic Pricing Software
$20–$60/month per listingPriceLabs, Wheelhouse, and Beyond are the three main options. Not optional if you want to compete on revenue. Budget $30/month ($360/year) as a baseline.
Property Taxes
Varies by county — use actual assessed valuePull the current tax bill from the county assessor. Be aware that some counties reassess at sale and your tax bill may increase significantly after closing.
⚠️ HOA Fees (if applicable)
$50–$500+/monthSome HOAs prohibit STR activity entirely. Always review the HOA CC&Rs before underwriting. If the HOA bans rentals shorter than 30 days, the deal is dead before the numbers start.
Permit and License Fees
$100–$1,000+/year depending on jurisdictionMany cities require annual STR permits. Some markets have caps on permits — which means you may not be able to operate legally even if you wanted to.
The items marked ⚠️ are the ones beginners most commonly underestimate or skip entirely.
Property management fees, STR insurance, and the furnishing reserve alone can add $12,000 to $20,000 in annual costs that do not appear in the seller's pro forma. Include all of them every time.
4Step 3: The Three Metrics That Matter
Once you have revenue and expenses built, you calculate three numbers. These tell you whether the deal is worth pursuing, what return you are buying, and how much cushion you have if things go wrong.
Cash-on-Cash Return (CoC)
Annual Cash Flow / Total Cash Invested
Cash-on-cash is the most important metric for a leveraged STR purchase. It tells you what percentage of your invested capital you are getting back as cash each year. Total cash invested includes down payment, closing costs, and furnishing costs. A deal that returns 6% CoC at base case occupancy is marginal. A deal that returns 12% CoC is strong.
Break-Even Occupancy Rate
Total Annual Fixed Costs / (ADR x 365)
Break-even occupancy tells you how full the calendar needs to be before you stop losing money. This is the single most important risk metric for an STR deal. If your break-even occupancy is 55% and the market average is 60%, you have almost no cushion. If your break-even is 38% and the market average is 62%, you can weather a significant demand downturn or a bad regulation environment.
Revenue Per Available Night (RevPAN)
Gross Annual Revenue / 365
RevPAN is used to compare properties in the same market regardless of their occupancy or ADR individually. A property with a high ADR but low occupancy may have a lower RevPAN than one with a moderate ADR and consistently high occupancy. RevPAN is also the metric AirDNA uses for its market scoring, so it gives you an apples-to-apples comparison against market comps.
5Step 4: A Full Worked Example
Below is a complete underwriting for a real deal type: a 3-bedroom, 2-bath cabin near a popular mountain destination. Purchase price is $415,000. The seller is claiming $76,000 in annual income. You are going to build your own numbers.
Mountain Cabin — 3BR/2BA — Purchase Price: $415,000
AirDNA market data: $218 ADR / 61% occupancy / $133 RevPAN for comparable 3BR properties
Revenue (Conservative Case)
Operating Expenses (Annual)
Net Operating Income and Debt Service
Verdict on this deal at $415,000: Do not buy.
The conservative case produces a loss of $21,598 per year. Even the base case (market ADR and occupancy) produces negative cash flow after debt service at this purchase price. The seller's $76,000 revenue claim assumed peak-year performance and did not account for a full expense stack. This deal fails at any reasonable offer price without a significantly lower purchase price or a much stronger revenue market.
What purchase price makes this deal work?
Working backwards from a target 8% cash-on-cash return at conservative case revenue requires getting the debt service low enough that cash flow exceeds $0 with meaningful cushion. At $320,000 purchase price with a $240,000 loan at 8.1%, annual debt service drops to approximately $21,408, and base-case cash flow turns positive. The gap between the $415,000 ask and the $300,000 to $320,000 price needed tells you everything you need to know about whether this is a negotiable deal or one to walk away from.
6Step 5: Stress-Test the Deal
Every STR deal needs a sensitivity table. Revenue can drop in year one if reviews are not established, if a new competitor opens nearby, if regulations tighten, or if the broader travel market softens. Here is how to build one.
Take your base-case ADR and hold it constant. Then run five occupancy scenarios from 45% to 65% and calculate cash flow at each level. This tells you your downside tolerance.
| Occupancy | Gross Revenue | Eff. Gross Income | Total OpEx | NOI | Cash Flow* |
|---|---|---|---|---|---|
| 45% | $36,135 | $34,890 | $30,900 | $3,990 | -$19,530 |
| 50% | $40,150 | $38,745 | $31,800 | $6,945 | -$16,575 |
| 55% | $44,165 | $42,619 | $32,700 | $9,919 | -$13,601 |
| 60% | $48,180 | $46,494 | $33,600 | $12,894 | -$10,626 |
| 65% | $52,195 | $50,368 | $34,500 | $15,868 | -$7,652 |
*Cash flow assumes $311,250 loan at 8.1% on 30yr fixed = $27,576 annual debt service. ADR held at $218.
In this example, the deal is cash-flow negative at every occupancy level from 45% to 65% because the purchase price is too high relative to the revenue the market supports. A good deal should be cash-flow positive in the base case and only slightly negative in the worst-case scenario. If your table looks like this one, either negotiate the price down significantly or move on.
7The 5 Numbers Your Offer Must Clear
Before submitting any offer on an STR property, confirm the deal passes all five of these thresholds at conservative case assumptions. A deal that passes four of five is a deal to negotiate, not a deal to buy.
Cash-on-Cash Return: 8% or better at conservative occupancy
This is your minimum acceptable return for the risk and management intensity of operating an STR. Deals below 8% CoC at conservative projections do not have enough margin to survive a slow season or a regulation change.
Break-Even Occupancy: 50% or lower
If you need 58% occupancy to break even and the market average is 61%, a 5% market downturn puts you in the red. Break-even below 50% means you can survive a rough year without feeding the property from your personal income.
RevPAN: At or above the market median for comparable bedroom count
RevPAN below the market median means you are buying a property that underperforms its peers. That can be fixed with better photography and pricing, but only if the property itself is comparable quality. If it is already well-presented and still below median RevPAN, the location or property type is the problem.
Debt Service Coverage Ratio: 1.25 or higher at base case
DSCR = NOI / Annual Debt Service. A ratio of 1.25 means your NOI covers the mortgage with 25% to spare. Lenders require 1.25 DSCR for most investment property loans. More importantly, anything below 1.0 means you are covering mortgage shortfall from your own pocket every month.
Regulatory environment: STRs permitted without a cap or pending ban
This is not a number but it is the most important box on the checklist. If the city has capped permits at 200 and 195 are already issued, you may not be able to get a permit at all. If there is an active city council proposal to ban non-owner-occupied STRs, that needs to be factored into every number in your model.
8Green Flags vs. Red Flags
Green Flags
- ✓Market has demand from multiple independent sources (outdoor recreation, tourism, events, proximity to a major city)
- ✓Existing reviews on the listing are strong and numerous (reduces first-year revenue risk)
- ✓Market RevPAN has been stable or growing for 3+ years
- ✓Local STR ordinance is well-established with a clear permit process
- ✓Property has a differentiator: hot tub, game room, lakefront, mountain view, or sleeps 8+ guests
- ✓Seller has actual Airbnb payout statements, not estimated revenue
- ✓Break-even occupancy is below 45% at base case ADR
Red Flags
- ✕Seller provides only a single-year revenue number during peak COVID travel years (2021–2022)
- ✕HOA has pending vote on STR restrictions or recently added language about short-term rentals
- ✕Market is in an oversupply cycle (AirDNA market score declining, RevPAN falling year over year)
- ✕City has an active permit cap with a waiting list
- ✕Property is in a state with extremely high STR insurance requirements or frequent guest litigation
- ✕Numbers only work at the seller's optimistic revenue projection, not at independent market data
- ✕No data on competing listings in the immediate area — hard to validate your ADR and occupancy assumptions
The discipline that separates experienced STR investors from beginners
Experienced STR investors kill more deals than they close. They underwrite fast, stress-test hard, and walk away when the numbers do not work at conservative assumptions. The patience to pass on ten mediocre deals to find one great deal is the skill. The underwriting framework above is just the tool.
Post your deal analysis in the Short-Term Rentals forum before you make an offer. Members who have closed dozens of STR deals will review your numbers and tell you what you missed. That feedback is free and often worth more than any paid course.
Jordan Vance
STR Investor · 22 Properties · 412 points · REICommunity Contributor
Jordan has been investing in short-term rentals for 8 years across the Smoky Mountains, Gulf Coast, and Scottsdale markets. He has analyzed 300+ deals and built a 22-property portfolio averaging 14% cash-on-cash return. He posts deal breakdowns and underwriting walkthroughs in the Rentals forum weekly.
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