How to calculate DSCR: the formula, PITIA, and worked examples

The formula is one line:

DSCR = monthly rent ÷ monthly PITIA

That's the whole calculation. A property renting for $1,700 against a $1,360 total monthly payment has a DSCR of 1.24. Everything else in this post is about what belongs in each of those two numbers, because that's where the mistakes live. If you'd rather skip the arithmetic, the DSCR loan calculator runs it from your rent, price, and rate.

The reason lenders reduced an entire underwriting decision to one fraction is that on a DSCR loan, the property is the borrower. Your salary isn't in the equation. So the equation has to answer the only question that matters: does the rent cover the debt.

What PITIA actually means

PITIA is the acronym doing most of the work in that formula, and it's worth breaking apart because every letter is a place the number can go wrong.

P and I are principal and interest, the amortizing loan payment. Not the interest-only payment, unless that's the structure you're actually closing on.

T is property taxes, monthly. The reassessed figure at your purchase price, not the seller's current bill.

I is the insurance premium, monthly. A real quote, not a placeholder.

A is association dues. HOA, condo association, or any mandatory community fee. If the property has them, they're in the denominator whether or not you think of them as part of the mortgage.

Add those five and you have the full monthly cost the lender holds the rent against. Some lenders and some glossaries will say PITI instead of PITIA, which is the same thing minus association dues. If the property has an HOA, use PITIA and don't let the shorter acronym talk you out of a line item that can run $300 a month.

Walking through a real example

Take a $215,000 single-family with 25% down at a 7% rate on a 30-year fixed.

The loan is $161,250. Principal and interest come to $1,073. Property taxes are $200 a month and insurance is $100 a month. No HOA. Total PITIA is $1,373.

The property rents for $1,700.

$1,700 ÷ $1,373 = 1.24.

The rent covers the payment with about 24% to spare. Most lenders approve this deal, and it sits a rounding error below the 1.25 mark where pricing improves. Most lenders approve at 1.0 and price better at 1.25, and the thresholds each lender works from are worth knowing before you run your own number.

What counts in the denominator, and what doesn't

This table is the single most useful thing on this page, because the exclusions are what surprise people.

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The right-hand column is why a property can clear the lender's ratio and still disappoint you. Management, maintenance, and vacancy are real money leaving your account every year. They belong in your investment analysis, and every Lineage pro forma deducts them. They are simply not in the lender's DSCR calculation, because that calculation is asking a narrower question than you are.

The ratio asks whether the rent covers the debt. You still have to ask whether it covers everything else with margin left over, and the honest version of that answer is a cash-on-cash return, not a DSCR.

The gross-versus-NOI trap

You'll find two DSCR definitions in circulation, and they give different answers for the same property. This is the most common reason an investor's number doesn't match their lender's.

Residential DSCR loan programs use gross monthly rent ÷ PITIA. Commercial real estate and the finance textbooks use net operating income ÷ annual debt service, where the net operating income formula subtracts operating expenses from gross income first.

Neither is wrong. They're different tools built for different loans. But the gap between them is not small, and running the wrong one will make you think a fundable deal is a weak one. Same property from the example above, both ways:

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Identical house. Identical loan. A 0.22 spread, purely from convention. The operating expenses in the right-hand column assume 8% management, 5% maintenance, and a 5% vacancy allowance, which is a reasonable set of assumptions and exactly the set the residential formula ignores.

So when someone quotes you a DSCR, ask which convention they're using. When a residential DSCR lender quotes one, it's gross rent over PITIA.

Illustrative example. Actual rates, taxes, insurance, rents, and operating expenses vary by property and market.

Where each number actually comes from

The formula is easy. Sourcing the four inputs is where deals get delayed, and each one has an owner who isn't you.

Rent comes from the signed lease if the property is tenanted, or from the appraiser's market rent schedule if it isn't. On the Lineage marketplace, rent figures come from the local property manager's signed leases rather than an estimate, which matters because the lender is going to verify it against someone independent regardless.

Taxes come from the county at the reassessed value, and reassessment happens at sale in most jurisdictions. Underwriting off the seller's tax bill is the most expensive shortcut on this list.

Insurance comes from a bound quote on the actual property, with the actual deductible and the actual coverage. A placeholder number that's off by $80 a month moves the ratio in the example above by roughly 0.07, which is enough to cross a pricing tier. In high-premium markets this is the line that decides the deal, which is why insurance belongs in the transaction rather than after it.

Association dues come from the HOA or condo docs, and they can be raised by a board vote you have no say in.

How to work the formula backwards

Most investors run DSCR forward: here's the property, what's the ratio. Running it backward is more useful when you're shopping, because it tells you what you can actually afford before you fall for a listing.

Start with the rent and the ratio you need. A property renting for $1,700 at a target of 1.25 gives you a maximum PITIA of $1,700 ÷ 1.25, or $1,360. Subtract the $300 you're expecting in taxes and insurance and you have $1,060 to spend on principal and interest. At 7% over 30 years, $1,060 a month supports a loan of roughly $159,300. At 25% down, that's a purchase price around $212,400.

So on that rent, in that market, at that rate, your ceiling is about $212,000. A $230,000 listing renting for the same $1,700 doesn't work at 1.25 no matter how much you like the kitchen, and no amount of underwriting creativity changes it.

That's the calculation worth doing before you tour anything. It converts a rent number into a price number, which is the form the decision actually takes. The calculator will run it in either direction.

Illustrative example. Actual rates, taxes, insurance, and lending terms vary by property, market, and program.

How to calculate DSCR on a vacant property

No lease means no rent figure, so the appraiser supplies one. The appraisal comes with a rent schedule, sometimes called a 1007, giving the appraiser's opinion of market rent based on comparable rentals in the area.

That number is the numerator. Not your estimate. Not the seller's projection. Not what the listing says it "could rent for."

This is a feature rather than a hurdle. The rent figure in your DSCR is being set by someone with no stake in whether the deal closes, which means a ratio that clears on an appraiser's rent schedule has already survived one independent check.

How to calculate DSCR on a duplex or fourplex

Multi-unit works the same way with one addition: you total the gross scheduled rent across all units, then divide by the single PITIA for the whole property.

A $260,000 duplex with 25% down at 7.25% carries a $195,000 loan and about $1,330 in principal and interest. Add $260 in taxes and $150 in insurance and PITIA is $1,740. Unit A rents for $1,050 and Unit B for $1,100, so gross scheduled rent is $2,150.

$2,150 ÷ $1,740 = 1.24.

Note what the calculation does not do. It doesn't discount for the fact that one of the two units will probably turn over this year. Vacancy isn't in the residential formula, on one unit or on four. Whether you buy a single-family or a multifamily property first, the arithmetic is identical. Only the number of leases changes.

If a unit is vacant at the time of underwriting, that unit's rent comes from the appraiser's schedule and the leased units come from their leases. Lenders will mix the two sources in the same calculation.

Illustrative example. Actual rates, taxes, insurance, and rents vary by property and market.

How to calculate DSCR on a short-term rental

This is where programs diverge, so the honest answer is that you have to ask.

Some lenders won't count short-term rental income at all and will underwrite the property on its long-term market rent, which usually produces a lower ratio than the property actually earns. Others accept a trailing 12-month revenue history on a property with an operating record. Others accept third-party market data for a property without one, typically with a haircut.

Three questions settle it before you spend money on an appraisal. Does the program accept short-term rental income. What document proves it. And is the figure used gross revenue or revenue net of platform fees and cleaning. The answers change the numerator enough that two lenders can quote you ratios 0.30 apart on the same property.

Interest-only changes the denominator

An interest-only payment is smaller than an amortizing one, so it produces a higher DSCR on the identical loan. This is worth understanding because it's the most common reason a quoted ratio looks better than you expected.

The $161,250 loan at 7% costs $1,073 a month amortizing. Interest-only, it costs $941. Add the same $300 in taxes and insurance and PITIA drops from $1,373 to $1,241, which takes the ratio from 1.24 to 1.37.

Same house, same rent, same loan amount, 0.13 of additional ratio from the payment structure alone. That's real, and some programs will underwrite to it. It's also worth remembering that you aren't paying down principal during the interest-only period, which is a different conversation about debt paydown than the one the ratio is having. When you see a DSCR quoted, confirm which payment structure it assumes.

Five ways the calculation goes wrong

Every one of these produces a number that looks fine and isn't.

Mixing monthly and annual. Monthly rent over annual debt service is off by a factor of 12. Pick one unit and hold it on both sides.

Using the seller's tax bill. Reassessment at your purchase price can move the tax line meaningfully, and it moves it in one direction.

A placeholder insurance number. Real quote or the ratio is fiction, particularly in coastal and high-premium markets.

Forgetting association dues. They're in PITIA. A $300 monthly HOA on the example property drops the ratio from 1.24 to 1.02.

Running the NOI version by accident. You'll conclude the deal is weaker than the lender does and walk away from something fundable.

How to raise a DSCR

Only three levers move a DSCR, and which one to pull first depends on how far the deal sits from your target: a larger down payment, a lower rate, or higher rent.

Everything else about you and your finances leaves the number exactly where it was. That's the point of the product. The six things lenders check on a DSCR file are a short list, and your employer isn't on it.

Check your math against the lender's before you spend anything

Run your own number first. Then run the lender's version, meaning gross rent over full PITIA with a real tax figure and a real insurance quote. If those two disagree by more than a rounding error, find out which input is different before you order an appraisal.

There's a broader point in the ratio worth sitting with. A lender approving your DSCR loan is independently confirming that the deal math works, which is a second opinion you're getting for free. If you have to strain and round in your favor to reach 1.0, that isn't a paperwork problem. That's the deal talking. Getting lending and insurance quoted inside the same transaction is what keeps the denominator from moving on you three days before closing.

Examples are illustrative. Actual rates, taxes, insurance, and rents vary by property and market. This is educational content, not financial advice.