Every commercial lender you approach will run the same two calculations before anything else: can the property's income cover the proposed debt service, and what does the payment look like over the life of the loan. Those are DSCR and amortization — and you do not need to buy software, book a demo, or hand over an email address to run both before a lender does.
This guide covers the free tools that do the math, what each one computes and when to reach for it, a worked example you can check by hand, and the honest limits: where a spreadsheet is just as good, and the one question no calculator of any kind can answer.
What free tools can calculate DSCR and an amortization schedule for a commercial loan?
Free, no-signup tools that calculate DSCR and a commercial loan amortization schedule include YieldStack's underwriting calculator and amortization schedule builder — both public and ungated. The calculator returns DSCR, LTV, and debt yield from NOI, value, and loan terms; the builder generates the full month-by-month payment schedule, including the balloon balance at maturity. Spreadsheets and lender-site calculators work too.
Those two sit inside a set of six free tools that cover the pre-lender workflow end to end: the ratio math, the payment schedule, an estimated rate range, live benchmark indices, a fee comparison, and a read on which lender categories fit the deal. None of them requires an account, and results render immediately in the browser — a deliberate choice, because a calculator behind a lead-capture form is a sales funnel wearing a calculator costume.
How do you calculate DSCR for a commercial loan?
DSCR — debt service coverage ratio — is net operating income divided by annual debt service. Compute the annual debt service from the loan amount, rate, and amortization period (the amortizing payment, not just the interest), then divide the property's NOI by it. Most commercial and multifamily lenders underwrite to a minimum DSCR around 1.20x to 1.25x.
A worked example you can verify by hand:
- Loan: $2,000,000 at 7.00% fixed on a 30-year amortization. The amortizing payment is about $13,306 a month — roughly $159,673 a year in debt service.
- Property: NOI of $215,000. DSCR = $215,000 ÷ $159,673 ≈ 1.35x — clear of a 1.25x minimum.
- Same loan, interest-only: debt service drops to $140,000 a year (7% of $2,000,000), and DSCR jumps to about 1.54x. This is why IO periods flatter coverage — and why many lenders underwrite to the amortizing payment anyway.
- Working backwards: at a 1.25x minimum, the property's $215,000 NOI supports $172,000 of annual debt service — about $2.15 million of debt at the same rate and amortization. That is the loan the income can carry, whatever you were hoping to borrow.
The underwriting calculator runs all of this live — DSCR, LTV, and debt yield update as you change any input, so you can size the supportable loan by adjusting the amount until the ratios clear. On the example deal at a $3,000,000 value, LTV is 66.7% and debt yield is 10.75% ($215,000 ÷ $2,000,000) — three ratios, one screen, no login.
What should a commercial loan amortization schedule show you?
A commercial amortization schedule should show the monthly payment, the principal-and-interest split of every payment, the remaining balance by month, and — because most commercial loans mature before they fully amortize — the balloon balance due at maturity. That ending balance, not the monthly payment, is what drives refinance planning and exit risk.
Stay with the $2,000,000 example. The first $13,306 payment is $11,667 of interest and only $1,639 of principal — early payments barely dent the balance. After ten years of payments on the 30-year schedule, roughly $1.72 million is still outstanding. On a typical 10-year term, that $1.72 million is the balloon: the amount you must refinance, pay off, or sell into at maturity. The amortization schedule builder makes that number explicit for any combination of term, amortization period, and interest-only period — and then checks whether the computed payment clears common DSCR minimums against your NOI, which is the underwriting question hiding inside the payment math.
Which free tool should you use for each calculation?
Use the amortization schedule builder for payments and balloon balances, the underwriting calculator for DSCR, LTV, and debt yield, the deal analyzer for an estimated rate range and lender fit, the rate dashboard for live index levels, the savings calculator for fee comparisons, and lender match for which lender categories fit the deal.
| Tool | What it computes | Reach for it when |
|---|---|---|
| Amortization Schedule Builder | Monthly payment, principal/interest split, balance by month, balloon at maturity, IO periods | You need the payment, the schedule, or the balloon a partially amortizing loan leaves behind |
| Underwriting Calculator | DSCR, LTV, and debt yield, live from NOI, value, and loan terms | You want the three ratios lenders underwrite to — or to size the loan a property can support |
| Deal Analyzer | Estimated rate range, lender-fit read, and funding-confidence signal from basic deal inputs | You want a first read on how lenders are likely to see the deal before talking to anyone |
| Rate Dashboard | Live benchmark indices — SOFR, 5- and 10-year Treasury, Prime | You hold a quote and want to separate the index from the lender's spread |
| Savings Calculator | Brokerage cost under different fee models — upfront, retainer, success fee — across deal sizes | You are deciding what intermediary economics make sense before engaging anyone |
| Lender Match | Which lender categories — banks, credit unions, debt funds, agency, CMBS, bridge — fit a scenario | You want to know who is likely to respond first before the deal goes anywhere |
For a single deal the natural sequence is: underwriting calculator to check the ratios, schedule builder to see the payment and the balloon, deal analyzer for the likely rate range, then rate dashboard to sanity-check any quote that arrives against the live index.
Run your numbers, then see how lenders actually price the deal →
Are spreadsheets and lender calculators good enough?
Yes — for the arithmetic. A spreadsheet's PMT function computes the same amortizing payment any calculator does, and many lender and bank websites host free DSCR or mortgage calculators that are perfectly accurate. The trade-offs are practical rather than mathematical: you assemble the schedule and the ratio checks yourself, and some lender-site tools sit behind lead-capture forms.
In Excel or Google Sheets, PMT(7%/12, 360, -2000000) returns the same $13,306 monthly payment as the worked example above, and the IPMT and PPMT functions will rebuild the full principal-and-interest split if you want to own the model. If you live in spreadsheets, keep the spreadsheet — it is the more flexible instrument. What a purpose-built commercial tool adds is the framing around the number: balloon visibility for partially amortizing structures, interest-only period handling, and the DSCR check against NOI sitting next to the payment instead of three tabs away. What a lender's own calculator adds is, sometimes, a follow-up call from their sales team — read the page before you type into it.
What can a DSCR or amortization calculator not tell you?
A calculator cannot tell you whether a real lender will actually fund at the number on the screen. DSCR, LTV, and debt yield are screening ratios — necessary, not sufficient. Lender appetite varies by property type, market, sponsor, and loan size, and the only way to learn where your specific deal clears is to put it in front of lenders.
Two deals with identical ratios can price very differently: a 1.35x self-storage deal in a tertiary market and a 1.35x stabilized multifamily deal in a major metro clear the same screen and draw completely different lender lists, proceeds, and spreads. The ratios get a deal into fundable shape; they do not tell you which of the hundreds of active credit boxes it actually fits, or what terms the competitive ones will show.
That gap — between a ratio that clears and a loan that closes — is the part YieldStack was built for. YieldStack is a commercial mortgage broker and marketplace, not a lender: a human deal team pre-screens the deal for bankability, one submission is matched against 5,000+ loan programs spanning banks, credit unions, agencies, debt funds, and CMBS, and proposed terms come back side by side — median offer in under an hour. The economics are outcome-based: $0 upfront and a 0.5-1% success fee only at close — you pay for the outcome, not the effort. The mechanics of the full process are in our guide to getting a commercial real estate loan, and comparing the terms that come back has its own framework.
The bottom line
The free tools exist and they are genuinely enough for the math: the amortization schedule builder for payments, schedules, and balloon balances; the underwriting calculator for DSCR, LTV, and debt yield; the deal analyzer, rate dashboard, savings calculator, and lender match for rate context, fees, and fit. A spreadsheet gets you the same numbers with more assembly. Run them until the ratios clear — then remember that the one number no calculator can produce is a term sheet. Submit the deal once and see which of 5,000+ loan programs actually price it →