This DSCR calculator computes the debt service coverage ratio — net operating income ÷ total debt service (principal + interest) — the number real-estate and business lenders underwrite to. Where interest coverage ignores principal, DSCR counts the whole payment: it asks whether the property or business earns enough to pay ALL of its debt bill, with margin.

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Why Lenders Underwrite to Coverage, Not Collateral

A loan repaid by a property’s income is only as safe as the income’s margin over the payment — that margin IS DSCR. The defaults: NOI $120,000 against debt service of $55,000 interest + $35,000 principal = $90,000 → 1.33×, meaning NOI can fall about 25% before the payment goes uncovered. Lender minimums cluster at 1.20–1.25× for stabilized commercial real estate (SBA business-acquisition loans often underwrite 1.10–1.25× on global coverage), and the ratio runs loan sizing backwards: at a required 1.25×, this NOI supports maximum annual debt service of $96,000 — which, at a given rate and amortization, caps the loan amount itself. DSCR, not the borrower’s enthusiasm, writes the term sheet.

Its numerator discipline matters: NOI excludes debt service and income taxes but must honestly include vacancy allowance, management, reserves for replacement and realistic expenses — the seller’s “NOI” in a brochure and the lender’s underwritten NOI are famously different documents, and the gap is where deals re-trade. Note also what DSCR does to interest-only loans: with principal at zero, DSCR inflates toward interest coverage — which is precisely the maturity-day risk (the whole principal still due at the end) the ratio then hides. Read DSCR with the amortization schedule attached.

Worked Examples (Verified)

  • Defaults: 120,000 ÷ 90,000 = 1.33× — inside the bankable band, cushion 25%.
  • The loan-sizing inverse: NOI $120k at a 1.25× minimum supports $96,000/yr of debt service; at 7% on a 25-year amortization (annual mortgage constant ≈ 8.48%), that’s ≈ $1.13M of loan — coverage arithmetic converting directly into proceeds.
  • The rate-shock case: refinancing lifts debt service to $115,000 → DSCR falls to 1.04× — the same property, the same rents, suddenly unbankable at standard terms. DSCR is an interest-rate exposure measure as much as a property metric.

DSCR Discipline

  • Underwrite NOI, don’t transcribe it: normalize vacancy (5%+ even when full), management fees (even if self-managed) and replacement reserves, or the ratio flatters reality.
  • Global vs property DSCR: business loans (SBA) typically add the owner’s other income/debts and personal living draw — know which universe your lender is computing in.
  • Interest-only periods flatter DSCR temporarily; compute the ratio at the amortizing payment too before celebrating eligibility.
  • Trailing vs forward: lenders stress NOI (haircuts to market rents, expense loads); your best-case forward DSCR and their stressed DSCR can differ by 0.3× — negotiate from theirs.
  • Breakeven occupancy is DSCR’s cousin: (operating expenses + debt service) ÷ gross potential income — the vacancy the property can survive; useful sanity check alongside.

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Frequently Asked Questions

How do you calculate DSCR?

Net operating income ÷ total annual debt service, where debt service = scheduled principal + interest. Defaults: $120,000 ÷ ($55,000 + $35,000) = 1.33×. This calculator takes NOI and the two payment components separately so the full payment structure stays visible — and reports the NOI cushion percentage alongside the multiple.

What DSCR do lenders require?

Most commercial real-estate lenders set minimums around 1.20–1.25× for stabilized properties; stronger assets/sponsors sometimes clear 1.15×, weaker ones are held to 1.35×+. SBA 7(a) business loans commonly underwrite around 1.10–1.25× on a global basis. Below 1.0× the operation doesn’t cover its own payment and conventional credit is effectively closed. Requirements flex with rate environment and asset class — hotels and special-use properties sit at the strict end.

How is DSCR different from interest coverage?

Denominator completeness: interest coverage divides by interest alone; DSCR divides by interest PLUS scheduled principal — the entire contractual payment. A loan can show 2.2× interest coverage and only 1.15× DSCR when amortization is aggressive. Corporate analysis leads with interest coverage (principal is refinanced, not amortized, in bond-land); real-estate and small-business lending leads with DSCR because their loans actually amortize.

How does DSCR size a loan?

Divide NOI by the required coverage to get maximum allowable debt service, then convert that payment into a loan amount at the market rate and amortization. $120,000 ÷ 1.25 = $96,000/yr; at 7%/25-year amortization (annual constant ≈ 8.48% of the loan) that’s ≈ $1.12M. Raise rates or shorten amortization and the same NOI supports less debt — the mechanism by which rate hikes shrink commercial real-estate proceeds before prices adjust.

What NOI should I use?

The underwritten kind: rental income at realistic (not pro-forma peak) levels, minus vacancy allowance, operating expenses, management fees and replacement reserves — excluding debt service, income taxes and depreciation. Seller NOI in marketing packages systematically omits reserves and management and assumes zero vacancy; normalizing those three items is the difference between your DSCR and the lender’s, and the lender’s is the one that funds.

Does an interest-only loan have a better DSCR?

Mechanically yes (principal = 0 shrinks the denominator) and economically not really: the principal hasn’t vanished, it’s been deferred to a balloon the borrower must refinance or repay, often under unknowable future conditions. Sophisticated lenders compute DSCR on a hypothetical amortizing payment even for IO structures. When you evaluate an IO deal yourself, run this calculator both ways — contractual payment and shadow-amortized payment — and respect the uglier number.

What is global DSCR?

The SBA/small-business variant: (business cash flow + owner’s other income) ÷ (business debt service + owner’s personal debts and draws). It recognizes that in owner-operated businesses the firm’s coverage and the family’s finances are one system. A business posting 1.40× standalone can fail globally if the owner carries heavy personal obligations — and pass at 1.15× business-only with a clean personal balance sheet. Ask your lender which definition governs before optimizing the wrong one.

Is this DSCR calculator free?

Yes — free, instant, no sign-up. Enter NOI, annual interest and scheduled principal for DSCR, the cushion and the lender-band read.