Every Financial Ratio Investors Should Know
Financial ratios are the language of business analysis. They translate raw financial statements into comparable metrics that reveal how efficiently a company operates, how profitable it is, how much risk it carries, and whether its stock is reasonably priced. A single number from an income statement or balance sheet means almost nothing in isolation. Revenue of $50 billion tells an investor nothing about whether the company is well-managed. But revenue per employee of $500,000, compared to an industry average of $300,000, tells a clear story about operational efficiency. Financial ratios provide this context, converting absolute numbers into relative measures that can be compared across companies, industries, and time periods.
The ratios covered here fall into five categories: valuation, profitability, leverage, liquidity, and efficiency. No single ratio tells the complete story of a business. The goal is to assemble a mosaic from multiple ratios, each illuminating a different facet of the company's financial health and investment attractiveness.
Valuation Ratios
Valuation ratios compare a company's market price to some measure of its financial performance or net worth. They answer the question: how much am I paying for each dollar of earnings, cash flow, book value, or revenue?
Price-to-Earnings (P/E) = Stock Price / Earnings Per Share
The most widely quoted valuation metric. A P/E of 20 means investors are paying $20 for every $1 of earnings. Trailing P/E uses the last 12 months of reported earnings. Forward P/E uses analyst estimates for the next 12 months. The S&P 500's long-term average P/E is approximately 16-17. Higher P/E ratios imply the market expects faster earnings growth; lower ratios imply slower growth or higher risk.
Price-to-Earnings Growth (PEG) = P/E / Annual Earnings Growth Rate
Adjusts P/E for the expected growth rate. A PEG of 1.0 suggests the stock is fairly valued relative to its growth. Peter Lynch considered PEG below 1.0 as potentially undervalued. The ratio has limitations: it does not account for the quality or sustainability of the growth, and it treats all growth rates as equally reliable.
Price-to-Book (P/B) = Stock Price / Book Value Per Share
Compares market price to the accounting net worth per share. A P/B below 1.0 means the stock trades for less than its book value, which was historically a strong value signal. The ratio is most useful for asset-heavy businesses (banks, real estate, industrials) and least useful for asset-light businesses (software, brands, services) whose value resides in intangible assets not captured on the balance sheet.
Price-to-Sales (P/S) = Market Cap / Annual Revenue
Useful for companies with no earnings or highly variable earnings, since revenue is harder to manipulate than earnings and is always positive. A P/S of 2.0 means investors pay $2 for every $1 of revenue. The ratio does not account for profitability, so a low P/S on an unprofitable company may not indicate a bargain.
Price-to-Free-Cash-Flow (P/FCF) = Market Cap / Free Cash Flow
Many investors prefer P/FCF to P/E because free cash flow is harder to manipulate than earnings and better represents the cash available to shareholders. A company with a P/E of 25 but a P/FCF of 15 may be more attractive than its P/E suggests, indicating that capital expenditures are lower than depreciation or that working capital is being released.
Enterprise Value-to-EBITDA (EV/EBITDA) = Enterprise Value / EBITDA
Enterprise value equals market cap plus net debt (total debt minus cash). EBITDA is earnings before interest, taxes, depreciation, and amortization. EV/EBITDA is preferred by many analysts because it accounts for capital structure differences and is comparable across companies with different leverage. A lower EV/EBITDA, all else equal, indicates a cheaper valuation. The S&P 500 median EV/EBITDA has typically ranged from 10 to 14.
Earnings Yield = EPS / Stock Price (or EBIT / Enterprise Value)
The inverse of P/E. An earnings yield of 5% (P/E of 20) can be compared directly to bond yields to assess relative attractiveness. When the earnings yield on stocks exceeds the yield on investment-grade bonds by a wide margin, stocks are relatively cheap. When the spread narrows or inverts, stocks are relatively expensive.
Dividend Yield = Annual Dividends Per Share / Stock Price
Measures the income return on a stock investment. A dividend yield of 3% means a $100 investment generates $3 per year in dividends. High yields can indicate genuine value (a stable business with a depressed stock price) or a yield trap (a company whose dividend is about to be cut because the business is deteriorating).
Profitability Ratios
Profitability ratios measure how effectively a company converts revenue into profit and how efficiently it uses its capital.
Gross Margin = (Revenue - Cost of Goods Sold) / Revenue
Measures the percentage of revenue remaining after direct production costs. A gross margin of 60% means the company retains $0.60 of every revenue dollar after paying for the goods or services it sells. High gross margins (above 50%) typically indicate pricing power or a differentiated product. Low gross margins (below 20%) suggest a commoditized business where competition is primarily on price.
Operating Margin = Operating Income / Revenue
Measures profitability after all operating expenses (cost of goods sold, selling expenses, general and administrative expenses, research and development) but before interest and taxes. Operating margin reveals how efficiently the core business is run, independent of capital structure and tax jurisdiction. Apple's operating margin of approximately 30% indicates extraordinary operational efficiency. A grocery chain operating at 3% indicates a volume-driven, thin-margin business.
Net Profit Margin = Net Income / Revenue
The bottom-line profitability measure. It captures all expenses, including interest, taxes, and non-operating items. Net margin is most useful for comparing companies within the same industry, as different industries have structurally different margin profiles.
Return on Equity (ROE) = Net Income / Shareholders' Equity
Measures the return earned on shareholders' invested capital. An ROE of 20% means the company generates $20 of profit for every $100 of equity. High ROE can indicate either genuine business quality or the effect of leverage (high debt reduces equity, mechanically increasing ROE). Adjusting for leverage by examining ROE alongside debt ratios provides a clearer picture.
Return on Assets (ROA) = Net Income / Total Assets
Measures profitability relative to the total asset base, removing the effect of leverage. ROA is particularly useful for comparing financial institutions, where leverage varies widely and ROE can be misleading.
Return on Invested Capital (ROIC) = NOPAT / Invested Capital
NOPAT is net operating profit after taxes. Invested capital is total equity plus total debt minus excess cash. ROIC measures the return the business generates on all the capital invested in it, regardless of whether that capital came from shareholders or lenders. ROIC above the weighted average cost of capital (WACC) indicates value creation. ROIC below WACC indicates value destruction. This is arguably the single most important profitability ratio for assessing business quality.
Leverage Ratios
Leverage ratios measure the degree to which a company relies on debt financing and its ability to service that debt.
Debt-to-Equity = Total Debt / Shareholders' Equity
A D/E of 0.5 means the company has $0.50 of debt for every $1.00 of equity. Higher ratios indicate more leverage, which amplifies both returns and risks. What constitutes an acceptable D/E ratio varies dramatically by industry. Utilities and real estate companies routinely operate with D/E ratios above 1.0. Technology companies often operate with D/E ratios below 0.3.
Debt-to-EBITDA = Total Debt / EBITDA
Measures how many years of operating earnings it would take to repay all debt. A ratio above 4.0 is generally considered high leverage for most industries. Credit rating agencies use this ratio extensively in their assessments.
Interest Coverage = EBIT / Interest Expense
Measures how easily a company can pay its interest obligations from operating earnings. Graham recommended a minimum interest coverage of 5x for investment-grade industrial companies. A ratio below 2.0 indicates potential distress, as even a modest decline in operating earnings could jeopardize the company's ability to service its debt.
Net Debt-to-EBITDA = (Total Debt - Cash) / EBITDA
A refinement of Debt-to-EBITDA that credits the company for cash on hand. A company with $5 billion in debt and $3 billion in cash has net debt of only $2 billion. This distinction matters significantly for technology companies like Apple and Microsoft, which carry substantial debt but also hold enormous cash balances.
Liquidity Ratios
Liquidity ratios measure a company's ability to meet its short-term obligations.
Current Ratio = Current Assets / Current Liabilities
Graham recommended a minimum current ratio of 2.0 for industrial companies. A ratio below 1.0 means the company has more short-term obligations than short-term assets, which is a potential red flag (though some well-managed businesses with strong cash flows, like Amazon, routinely operate with current ratios below 1.0).
Quick Ratio = (Cash + Receivables + Short-Term Investments) / Current Liabilities
A more conservative measure than the current ratio because it excludes inventory, which may be difficult to convert to cash quickly. A quick ratio above 1.0 indicates the company can meet all short-term obligations without selling any inventory.
Cash Ratio = Cash and Equivalents / Current Liabilities
The most conservative liquidity measure. A cash ratio above 1.0 means the company can pay all short-term obligations with cash on hand alone. Very few companies maintain this level of cash, but those that do (like Berkshire Hathaway with its massive cash reserves) have extraordinary financial flexibility.
Efficiency Ratios
Efficiency ratios measure how effectively a company uses its assets and manages its operations.
Asset Turnover = Revenue / Total Assets
Measures how much revenue the company generates from each dollar of assets. A high asset turnover ratio indicates efficient use of assets. Retailers like Walmart typically have high asset turnover (around 2.5) and low margins. Software companies like Microsoft have low asset turnover (around 0.5) and high margins. Both can produce strong returns; the path to profitability differs.
Inventory Turnover = Cost of Goods Sold / Average Inventory
Measures how many times inventory is sold and replaced during the year. A turnover of 12 means inventory is replaced monthly. Higher turnover generally indicates better inventory management and less capital tied up in unsold goods. Declining inventory turnover can signal weakening demand or overproduction, a warning sign that often precedes earnings disappointments.
Receivables Turnover = Revenue / Average Accounts Receivable
Measures how quickly a company collects payment from customers. A ratio of 10 means the average receivable is collected in approximately 36 days. Declining receivables turnover, meaning customers are taking longer to pay, can indicate deteriorating credit quality of customers or aggressive revenue recognition practices where revenue is being booked before cash is collected.
Free Cash Flow Conversion = Free Cash Flow / Net Income
Measures how effectively reported earnings convert into actual cash. A conversion ratio consistently above 1.0 is a positive sign, indicating that the business generates more cash than it reports in earnings. A conversion ratio consistently below 1.0 suggests that capital expenditures, working capital absorption, or non-cash earnings components are consuming the reported profits. Companies with high FCF conversion are generally safer investments because their earnings are backed by real cash.
Using Ratios in Combination
Individual ratios can mislead. A company might have a high ROE (suggesting quality) achieved through excessive leverage (suggesting risk). It might have a low P/E (suggesting cheapness) paired with declining margins (suggesting deterioration). The discipline of ratio analysis lies not in examining any single metric but in assembling a complete financial profile from multiple ratios.
A practical screening approach might combine valuation metrics (P/E below 15, EV/EBITDA below 12) with quality metrics (ROIC above 15%, operating margin above 15%) and safety metrics (debt-to-EBITDA below 3, current ratio above 1.5). Companies that pass all three filters are cheap, high-quality, and financially sound, the intersection where the best investment opportunities typically reside.
The final caution is that ratios are backward-looking. They describe what the company has done, not what it will do. A company with perfect historical ratios can deteriorate if the competitive environment changes, management makes mistakes, or macroeconomic conditions shift. Financial ratios are the starting point of analysis, not the conclusion. They identify candidates for further investigation, which must include qualitative assessment of the business model, competitive position, and management quality.
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