How Commercial Lenders Underwrite a Loan: The Key Metrics and Ratios
By Zolvo Team · 2 min read
Underwriting is the credit decision at the heart of lending: will this borrower repay, and how much risk is the lender taking if it does not? Lenders answer that question with a set of metrics and ratios, each measuring a different piece of the risk. Understanding them is understanding how a loan gets approved, sized, and priced. This guide walks the key metrics commercial lenders use, grouped by the question each one answers.
Can the Borrower Afford It? Cash Flow Coverage
The first question is whether the borrower generates enough cash to service the debt. The core measure is the debt service coverage ratio (DSCR): net operating income divided by total debt service. A DSCR above one means income covers the payments, with a cushion; lenders typically want a minimum well above one. It is the single most common gate in commercial credit, and the DSCR calculator shows the maximum debt a given income supports.
Is There a Cushion in the Collateral?
The second question is what protects the lender if the borrower cannot pay. That is measured against the collateral:
- Loan-to-value (LTV). The loan amount as a percentage of the collateral's value; a lower LTV means more equity cushion.
- Advance rate and borrowing base. In factoring and ABL, the lender advances a percentage of eligible collateral. The advance rate applied to the eligible pool sets availability; the borrowing base calculator shows how it works.
- Debt yield. In commercial real estate, debt yield (net operating income over the loan amount) measures return independent of value, a check against inflated valuations.
How Good Is the Collateral Itself?
For receivables-backed lending, the quality of the collateral is as important as its size. Lenders test it with:
- Dilution. How much of gross receivables never converts to cash, through credit memos, returns, and short-pays. Higher dilution pushes the advance rate down; the dilution calculator shows the safe advance rate.
- Days sales outstanding. How long receivables take to collect. A high DSO signals slow or troubled collections.
- Concentration. How much of the pool sits with one debtor. A concentration limit caps single-debtor exposure.
Underwriting Is Only the Start
These metrics are not one-time gates. The same ratios a lender underwrites, DSCR, LTV, advance rate, dilution, become the terms it monitors over the life of the loan, usually as financial covenants tested on a schedule. A loan that looked strong at closing can deteriorate, and the early-warning signal is one of these metrics moving the wrong way. Underwriting sets the bar; ongoing monitoring checks the loan against it.
How Zolvo Fits
The metrics a lender underwrites only stay meaningful if the data behind them stays accurate. Zolvo keeps the receivables, balances, and collateral data current against reconciled information, recomputes the borrowing base and eligibility as the book moves, and monitors DSCR, dilution, DSO, and concentration so covenant breaches surface early, through portfolio monitoring, on top of the systems a lender already runs. It turns the metrics set at underwriting into a live view of the loan.