Financial ratios turn raw statement numbers into comparable signals. A $2 million profit means little on its own; a 4% net margin against an industry average of 9% tells a story. This guide covers the four ratio families every analyst uses and how to avoid the traps that make ratios lie.
Liquidity ratios: can the company pay its bills?
Liquidity ratios measure whether a company can cover short-term obligations with short-term resources.
- Current ratio = current assets ÷ current liabilities. A value above 1.0 means short-term assets cover short-term debts, though healthy targets vary by industry (retailers run leaner than manufacturers).
- Quick ratio = (current assets − inventory) ÷ current liabilities. Strips out inventory, which may be slow to convert to cash.
- Cash ratio = cash and equivalents ÷ current liabilities. The most conservative test.
A current ratio that is too high isn't automatically good — it can mean cash is idling or inventory is piling up.
Profitability ratios: is the business making money efficiently?
- Gross margin = gross profit ÷ revenue. Reveals pricing power and production efficiency.
- Operating margin = operating income ÷ revenue. Adds the cost of running the business.
- Net margin = net income ÷ revenue. The bottom line after everything, including interest and tax.
- Return on equity (ROE) = net income ÷ shareholders' equity. What owners earn on their capital.
- Return on assets (ROA) = net income ÷ total assets. How productively the whole asset base is used.
Track margins over several periods. A single quarter can be noise; a three-year slide in gross margin is a strategy problem.
Leverage ratios: how risky is the capital structure?
- Debt-to-equity = total debt ÷ shareholders' equity. Higher leverage amplifies both returns and losses.
- Interest coverage = operating income ÷ interest expense. Below 2x is a warning sign in most industries.
- Debt-to-EBITDA is the ratio lenders watch most; covenants are often written against it.
Efficiency ratios: how hard are assets working?
- Inventory turnover = cost of goods sold ÷ average inventory. Low turnover means capital trapped on shelves.
- Receivables days (DSO) = accounts receivable ÷ revenue × 365. Rising DSO means customers are paying slower — a classic early sign of trouble.
- Asset turnover = revenue ÷ total assets. Pairs with margin: ROA = margin × turnover, the heart of DuPont analysis.
The mistakes that make ratios lie
- Comparing across industries. A software company and a grocery chain have structurally different margins and turnover. Always benchmark within the sector.
- Ignoring accounting choices. Leases, depreciation methods, and one-off items can distort comparisons between companies.
- Reading one ratio in isolation. Strong ROE with dangerous leverage is not strength. Read ratios as a system.
- Forgetting the trend. The direction and rate of change usually matter more than the level.
The fastest way to internalize ratios is to compute them on real statements. Our free ratio calculator lets you practice on realistic company data, and the Financial Statements Fundamentals course walks through every family of ratios lesson by lesson.