Good Debt Calculator for Small Businesses (2026)

Debt for a small business is a tool, not a moral question. The right framing is ROI math: does the use of borrowed capital produce returns greater than the cost of capital, with survivable downside? This calculator runs Brian Kim's 4-number test against your specific deal.

Quick answer: Run the ROI test on any business debt: enter the all-in cost of capital, the cash flow it should produce, your term, and a downside scenario — get a productive / workable / doesn't-pencil verdict.

How it works

Productive-debt verdict:
  • incremental cash flow ÷ cost of capital ≥ 1.5×  AND
  • downside cash flow ≥ debt service (i.e., DSCR ≥ 1.0 in the bad case)
  → productive debt

Workable-debt verdict (between productive and unworkable):
  • incremental cash flow ÷ cost of capital ≥ 1.0× but < 1.5×  OR
  • downside cash flow barely covers debt service

Doesn't-pencil verdict:
  • incremental cash flow < cost of capital  OR
  • downside cash flow can't service the debt
  • All-in dollar cost of capital: Total interest + fees + opportunity cost over the life of the loan or advance. Use the dollar number, not the APR — it forces an honest accounting.
  • Expected incremental cash flow: Net additional cash flow attributable to the use of funds (new revenue × gross margin − incremental operating cost). Should be plan-case, not best-case.
  • Downside scenario cash flow: What the same use of funds produces at 30% below plan — the survivability test.
  • Cost of not doing it: Lost revenue, capacity, or competitive position if you don't fund the project at all. Often understated.

Assumptions

  • The math is only as honest as the inputs — projections get cross-checked against historic gross margin and conversion data, not optimistic forecasts.
  • Ramp time is reflected in the incremental cash flow input (use the 12-month average, not month-12 run rate).
  • Cost of capital includes origination fees, closing costs, and prepayment penalties — not just stated APR.

Worked examples

Restaurant equipment — productive debt
  • All-in cost of capital: $8,000
  • Incremental cash flow (year 1): $22,000
  • Downside cash flow (30% under): $15,000
  • Cost of not doing it: $30,000 in deferred revenue

Productive — 2.75× return ratio AND downside still covers debt service. Math points to fund.

MCA covering operating losses — doesn't pencil
  • All-in cost of capital: $14,000
  • Incremental cash flow (year 1): $0 (covers losses, not new revenue)
  • Downside cash flow (30% under): −$8,000
  • Cost of not doing it: Cash-flow gap continues

Doesn't pencil — funding losses with high-cost capital compounds the structural problem. Restructure operating costs before adding debt.

Frequently asked questions

What is good debt vs bad debt for a small business?

There's no inherently good or bad loan product — debt is good when the use of borrowed money produces more cash flow than it costs, with survivable downside. Debt to buy equipment that lifts capacity, fund inventory for known demand, or finance a project with a clear return is usually productive. Debt to cover ongoing operating losses, with no new cash flow attached, usually isn't. The use of funds — not the product name — is what makes it good or bad.

How do I know if a business loan is good debt?

Run the ROI test: (1) the all-in dollar cost of capital — interest plus every fee — (2) the incremental cash flow the borrowed money should generate, (3) how that cash flow holds up in a downside scenario, and (4) the cost of not doing it at all. If incremental cash flow clears the cost of capital with room to spare and still covers the debt in the bad case, the math points to productive debt. This calculator runs the first three numbers and returns a verdict.

What ROI ratio makes business debt worth taking?

This tool uses the ratio of expected incremental cash flow to the all-in cost of capital. Roughly 1.5× or higher reads as productive — a clean win. Between 1.0× and 1.5× is workable but thin, so pressure-test the projection before committing. Below 1.0× the borrowed money doesn't earn back its own cost, so the math doesn't pencil yet. On top of that, if the downside scenario can't cover the cost of capital, the verdict flags it as too risky regardless of the base-case ratio.

Why does the calculator ask for a downside scenario?

Because a loan that only works in the best case isn't safe debt. The tool discounts your expected cash flow by the downside percentage you enter (30% below plan by default) and checks whether that conservative number still covers the cost of capital over the term. Downside survival is a hard gate — a deal can show a strong base-case return and still be flagged if it wouldn't survive a bad quarter.

Are merchant cash advances (MCAs) always bad debt?

No. The product is neutral — the use of funds decides. An MCA at, say, a 1.28 factor over 8 months to stock inventory for a known seasonal sales period at healthy gross margin can be productive debt. The same MCA used to cover ongoing operating losses is not, because there's no new cash flow to service it. Enter your real numbers and let the ROI test settle it rather than judging the product by name.

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