Key Financial Ratios for M&A Due Diligence: The Top Metrics I Run on Every Acquisition Target

Key financial ratios for M&A due diligence are the standardized calculations a buyer, lender, and SBA underwriter each apply to a target’s trailing financials to decide whether an acquisition can be funded and repaid. The top three ratios that decide most deals are Debt Service Coverage Ratio (DSCR ≥ 1.5x), Adjusted EBITDA multiple (2.5x–4x for Main Street, 5x–7x for lower middle market), and Gross Margin (industry benchmark ± 300 bps). Six supporting ratios — current ratio, quick ratio, working capital ratio, debt-to-equity, customer concentration, and DSO/DIO/DPO — round out the underwriter’s pack. Run these in order and a lender can pre-qualify the deal in an afternoon.

Look, I’ve closed 300+ deals over 30 years, and I’ve watched more first-time buyers get lost in a 40-line financial model than I can count. You do not need 40 numbers. You need nine ratios, run in the right order, against the right thresholds. That’s what an SBA underwriter runs. That’s what a private lender runs. That’s what I run on every target inside Dealmaker Academy before we spend an hour on anything else.

This piece is the ratio pack. If you want the broader eight-metric assessment checklist (Adjusted EBITDA add-backs, revenue growth, free cash flow, working capital peg), read the companion piece on financial metrics for assessing acquisitions. This one goes deeper on the ratios specifically — the ones underwriters, sellers’ brokers, and your own accountant will all quote back at you.

The Top 3 Financial Ratios That Decide Most Acquisitions

These three ratios do 80% of the work in a first-look assessment. If a target fails on any of the three, either the deal structure changes or the deal is dead. Run these before you request the tax returns for year three.

1. Debt Service Coverage Ratio (DSCR) — Non-Negotiable Floor 1.5x

DSCR is Adjusted EBITDA divided by total annual debt service (principal + interest) on the acquisition loan. A DSCR of 1.5x means the business generates $1.50 of cash for every $1.00 of debt payment. The SBA requires 1.15x minimum. Real dealmakers require 1.5x. Below that, you have no margin for a bad quarter, no cushion for working capital swings, and no room to pay yourself.

• Formula: DSCR = Adjusted EBITDA ÷ (Annual Principal + Annual Interest)
• SBA floor: 1.15x
• Bankable target: 1.5x
• Strong deal: 2.0x or higher

2. EBITDA Multiple — The Price of the Business

The EBITDA multiple is the purchase price divided by trailing twelve months Adjusted EBITDA. It’s how you know whether the seller’s asking price is in the market or in the stratosphere. Main Street businesses (under $1M SDE) trade at 2.5x–4x. Lower middle market ($1M–$5M EBITDA) trades at 5x–7x. Anything above those bands needs a specific reason — recurring revenue, sticky customers, real growth — or you’re overpaying.

• Main Street (< $1M SDE): 2.5x–4x SDE
• Lower middle market ($1M–$5M EBITDA): 5x–7x
• Middle market ($5M–$25M EBITDA): 7x–10x
• Adjustment for recurring revenue: +1x to +2x

3. Gross Margin — The Business Model Test

Gross margin is (Revenue – Cost of Goods Sold) ÷ Revenue. It tells you whether the business has pricing power or is running on razor-thin margins that will collapse the first time input costs rise. Compare against the industry benchmark, not to some universal number. A distributor at 22% gross margin is healthy; a SaaS business at 22% is broken.

• Services (professional): 40%–60%
• SaaS / software: 70%–85%
• Manufacturing: 25%–40%
• Distribution / wholesale: 15%–30%
• Home services: 30%–50%
• Red flag: Gross margin more than 300 bps below industry benchmark without a documented reason

The Six Supporting Ratios Every M&A Lender Runs

Once the top three clear, the underwriter turns to six liquidity, leverage, and concentration ratios. These decide the loan structure — how much you can borrow, what covenants you’ll live under, and how much seller financing you’ll need to close the gap.

Current Ratio

Current assets divided by current liabilities. Measures whether the business can cover its next twelve months of obligations without selling long-term assets. Target 1.5x or higher. Below 1.0x means the business is technically insolvent on a working capital basis — and you’ll need to inject cash at close.

Quick Ratio (Acid Test)

(Current assets – Inventory) ÷ Current liabilities. Same test, but without inventory (which can’t always be liquidated at book value). Target 1.0x or higher. This ratio is especially important for inventory-heavy businesses where the current ratio can flatter a cash-poor operation.

Working Capital Ratio & the Peg

Working capital ratio = Working capital ÷ Revenue. Tells you how many dollars of working capital the business needs to generate a dollar of revenue. Combined with the working capital peg (the normalized level of working capital at close), this is one of the most-negotiated numbers in the deal. Get the peg wrong and you write a check to the seller in month one.

Debt-to-Equity Ratio

Total debt divided by shareholders’ equity. Under 2.0x is comfortable. Between 2.0x and 4.0x is aggressive but bankable in the right industry. Over 4.0x and either the industry is highly leveraged by nature (real estate, some manufacturing) or the balance sheet is a mess.

Customer Concentration Ratio

Revenue from the top customer divided by total revenue. This is a ratio the seller will not volunteer. Insist on it. If the top customer is over 15% of revenue, that’s a concentration risk and it belongs in the purchase price. If it’s over 25%, you either restructure with a large earnout tied to customer retention, or you walk. Top-5 customer concentration over 50% is a hard stop for most SBA lenders.

DSO, DIO, and DPO — The Cash Conversion Cycle

Days Sales Outstanding, Days Inventory Outstanding, and Days Payable Outstanding. Together they tell you how many days of cash the business ties up in operations. A retail distributor with DSO of 45, DIO of 60, and DPO of 30 has a 75-day cash conversion cycle — every dollar of growth requires 75 days of working capital investment. That number determines whether you finance growth from cash flow or from the credit line.

The Order to Run the Ratios

Sequence matters. Underwriters run these in this order because each ratio triages the next question. Skip the sequence and you’ll spend eight hours on a target you should have killed in twenty minutes.

1. Rebuild Adjusted EBITDA from tax returns. Every ratio below depends on this number being right. Personal vehicles, family salaries, one-time legal, discretionary owner expenses — adjust each with documented backup. Get it wrong here and every downstream ratio is wrong.
2. Calculate the EBITDA multiple at ask. Purchase price ÷ Adjusted EBITDA. If it’s outside the industry band without a defensible reason, either negotiate or walk before you spend another hour.
3. Model DSCR at the proposed loan structure. Adjusted EBITDA divided by proposed debt service. If DSCR is below 1.5x, the deal doesn’t close at that structure. Either the price comes down, the seller carries more, or the deal dies.
4. Check gross margin against industry. Anything more than 300 bps below benchmark needs an explanation before you go further.
5. Run the liquidity ratios (current, quick, working capital). These determine cash-at-close and whether you need a working capital line day one.
6. Run debt-to-equity and customer concentration. These shape the deal structure — earnouts, holdbacks, seller notes.
7. Calculate the cash conversion cycle (DSO + DIO – DPO). This tells you how much cash growth will consume.

The whole sequence takes 60–90 minutes on a business with clean books. On messy books, it takes a day — and messy books are themselves a diligence finding.

Common Mistakes Buyers Make With Financial Ratios

I’ve seen these mistakes end more deals than bad prices. Every one of them is avoidable.

• Using the seller’s EBITDA figure as-is. The seller (or their broker) will hand you an EBITDA that’s optimistic by 15%–30%. Rebuild it from tax returns and bank statements before you calculate a single ratio.
• Comparing ratios across industries. A 22% gross margin means one thing in distribution and a different thing in SaaS. Benchmark against the industry, not the internet average.
• Running DSCR at the seller’s proposed structure instead of the lender’s. The seller wants all cash. The lender wants a debt service ratio that clears 1.5x. Model DSCR at what the bank will actually approve, not what the seller wishes for.
• Ignoring customer concentration because “the customer loves the business.” They love the current owner. Retention through a change of control is a separate question. Price the risk in.
• Skipping the cash conversion cycle. Buyers get excited about EBITDA and forget that a growing business with a 90-day cash conversion cycle can starve itself out of business in year two.
• Not running the ratios at three-year averages. One good year followed by two flat years is not a growth story. Average the ratios across the trailing three years and you’ll see the real picture.

A Live-Deal Walkthrough: Running the Ratios on a $3.2M Ask

Let’s run the pack on a real deal we assessed inside the Protégé Community last quarter. HVAC service business. Seller asking $3.2M.

• Seller’s stated EBITDA: $850K
• Adjusted EBITDA after rebuild: $710K (removed a non-recurring insurance recovery and re-added owner’s replacement salary)
• EBITDA multiple at ask: $3.2M ÷ $710K = 4.5x — above the 4x ceiling for Main Street HVAC
• DSCR at 80% SBA 7(a) financing over 10 years: 1.28x — below the 1.5x threshold
• Gross margin: 42% — within HVAC industry band (38%–48%)
• Current ratio: 1.8x — healthy
• Customer concentration: Top customer 8%, top 5 at 22% — clean
• Cash conversion cycle: 32 days — strong for the sector

The business is real. The price is not. We countered at $2.6M with a $400K seller note over 5 years at 6%. That structure brought DSCR to 1.62x and the multiple to 3.66x on Adjusted EBITDA. Deal moved forward. If we’d relied on the seller’s EBITDA figure and skipped the DSCR model, we’d have overpaid by $600K and either strangled the business on debt service or walked away from a good asset over the wrong number.

That’s what the ratios do. They translate a seller’s story into a price a lender will fund.

Where to Practice on Real Deals

Ratios only stick when you run them on live targets. Inside Dealmaker Academy, we walk the full nine-ratio pack on active deals with the coaching team. The Protégé Community is where members swap ratio outputs on their own deals and get sanity checks from dealmakers running comparable targets. If you have a specific target on your desk right now, book a coaching call and we’ll run the pack with you on that deal.

Frequently Asked Questions

What are the top three financial ratios to focus on when assessing an acquisition target?

The top three financial ratios for assessing an acquisition target are Debt Service Coverage Ratio (DSCR), EBITDA multiple, and Gross Margin. DSCR must clear 1.5x for the deal to be bankable. The EBITDA multiple must fit the industry band (typically 2.5x–4x for Main Street businesses and 5x–7x for lower middle market). Gross margin must land within 300 basis points of the industry benchmark. If a target fails any of the three, the deal either restructures or dies.

What is a good DSCR for a business acquisition?

A DSCR of 1.5x is the working threshold for a bankable acquisition. The SBA minimum is 1.15x, but experienced buyers require 1.5x to leave cushion for a bad quarter, working capital swings, and owner compensation. A DSCR of 2.0x or higher is a strong deal. Below 1.5x, either the purchase price comes down, the seller carries more of the note, or the deal doesn’t close.

What EBITDA multiple is normal for buying a small business?

Main Street businesses (under $1M in Seller’s Discretionary Earnings) typically trade at 2.5x–4x SDE. Lower middle market businesses ($1M–$5M in EBITDA) trade at 5x–7x. Middle market ($5M–$25M EBITDA) trades at 7x–10x. Recurring-revenue businesses add 1x–2x to the base multiple. Anything above these bands needs a specific reason — growth, stickiness, contracted revenue — or the buyer is overpaying.

How do you calculate financial ratios for M&A due diligence?

Rebuild Adjusted EBITDA from three years of tax returns before running any ratio. Then calculate DSCR (EBITDA ÷ annual debt service), EBITDA multiple (price ÷ Adjusted EBITDA), gross margin (revenue minus COGS ÷ revenue), current ratio (current assets ÷ current liabilities), quick ratio (current assets minus inventory ÷ current liabilities), debt-to-equity (total debt ÷ equity), customer concentration (top customer revenue ÷ total revenue), and the cash conversion cycle (DSO + DIO – DPO). Run them in that order and the deal makes sense or it doesn’t inside 90 minutes.

What financial ratios do lenders use for SBA acquisition loans?

SBA underwriters run DSCR (minimum 1.15x, target 1.5x), debt-to-equity, current ratio, quick ratio, and working capital ratio. They also examine customer concentration (top-5 above 50% is typically a hard stop), gross margin against industry, and cash conversion cycle. The SBA cares most about DSCR and the buyer’s post-close ability to service debt while running the business.

What is a healthy current ratio for an acquisition target?

A current ratio of 1.5x or higher indicates the business can cover the next twelve months of obligations without selling long-term assets. Below 1.0x, the business is technically insolvent on a working capital basis, and the buyer will need to inject cash at close to keep operations running. Between 1.0x and 1.5x, the deal is doable but the working capital peg becomes a key negotiation point.

How is customer concentration measured in an M&A ratio pack?

Customer concentration is calculated by dividing revenue from the top customer (and top 5 customers) by total revenue. A top customer above 15% of revenue is a concentration risk that belongs in the purchase price. Above 25%, restructure with a large earnout tied to customer retention, or walk away. Top-5 customer concentration above 50% is typically a hard stop for SBA-backed acquisition loans.

What questions will a lender ask about financial ratios during acquisition financing?

A lender will ask how Adjusted EBITDA was derived, whether the DSCR clears 1.5x at the proposed loan structure, how the current and quick ratios compare to the industry, what the customer concentration looks like, how the working capital peg was calculated, and whether the debt-to-equity ratio is defensible post-close. Prepare a one-page ratio summary with three-year trends before the lender meeting — it cuts underwriting time in half.

Where can I learn to run the full ratio pack on live acquisition targets?

Dealmaker Academy walks the nine-ratio pack on real acquisition targets with Carl Allen and the coaching team. The Protégé Community is where active dealmakers swap ratio outputs on their own targets. Both are built for people running deals, not people reading about deals.

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Next move: pick the last target you looked at and run the nine ratios in order. If the top three clear, the deal is worth another hour. See the companion breakdown on financial metrics for assessing acquisitions, or book a coaching call to walk the ratio pack on a live deal with the team.