Everything You Need to Know About What is a Common Size Income Statement [FAQ]
A common size income statement converts every line item into a percentage of total revenue, turning raw dollar figures into ratios that work across companies of any size. If Apple reports $394 billion in revenue and a net income of $97 billion, the common size version shows net margin at 24.6%. If a mid-cap competitor reports $4 billion in revenue with $400 million in net income, the same 10% net margin tells you immediately that Apple is far more efficient at the bottom line. That single reframing is the entire point of common size analysis: comparability without distraction.
This format is sometimes called vertical analysis because you divide each line by the same base (revenue) within a single period. Analysts use it to spot margin compression, benchmark against peers, and track how a business model shifts as a company scales.
Key Takeaways
- A common size income statement expresses every item as a percentage of revenue rather than in dollar terms.
- The format removes the size distortion that makes raw dollar comparisons between large and small companies meaningless.
- Net margin, gross margin, and operating margin all come directly from reading a common size income statement.
- Investors use it to track whether margins are expanding or contracting across multiple reporting periods.
- It pairs naturally with common size balance sheets and cash flow statements for a full-picture efficiency review.
- You can build one for any public company in minutes using ValueMarkers' screener, which surfaces the key ratios automatically.
What Is a Common Size Income Statement
The structure is straightforward. Take a standard income statement. Divide every line by total revenue. Multiply by 100 to get a percentage. The result is a table where revenue always equals 100% and every other item shows its share of that top line.
Here is what the structure looks like for a simplified company:
| Line Item | Dollar Amount | % of Revenue |
|---|---|---|
| Revenue | $1,000,000 | 100.0% |
| Cost of Goods Sold | $420,000 | 42.0% |
| Gross Profit | $580,000 | 58.0% |
| Operating Expenses | $250,000 | 25.0% |
| Operating Income (EBIT) | $330,000 | 33.0% |
| Interest Expense | $30,000 | 3.0% |
| Pre-Tax Income | $300,000 | 30.0% |
| Income Tax | $75,000 | 7.5% |
| Net Income | $225,000 | 22.5% |
Every percentage in the right column is a margin you can name. Gross profit at 58% is gross margin. Operating income at 33% is operating margin. Net income at 22.5% is net margin. These are the three numbers value investors watch most closely on an income statement.
Why Common Size Analysis Matters for Investors
Dollar figures mislead when companies operate at different scales. A company with $100 million in net income sounds profitable. Another with $10 billion in net income sounds more profitable. But if the first company earns 25% net margin and the second earns 4%, the first company's business model is structurally better, even though its absolute profit is smaller.
Common size analysis corrects that distortion instantly. It is particularly useful in three situations.
Peer benchmarking: you want to know whether Johnson & Johnson's 18% operating margin is strong or weak relative to sector peers. Common size statements make the comparison clean and direct.
Historical trend analysis: you want to see whether Apple's gross margin has held steady, expanded, or compressed over five years. Plotting the gross margin percentage across periods tells you whether pricing power is intact.
Acquisition due diligence: a buyer looking at two acquisition targets in the same sector can rank them by net margin, operating margin, and SG&A as a percentage of revenue without needing to normalize for size.
How to Build a Common Size Income Statement
The mechanics take about five minutes with a spreadsheet.
- Pull the income statement for the period you want to analyze. This can be annual or quarterly.
- Identify total revenue as your base. For most companies, this is the top line labeled "Revenue," "Net Revenue," or "Net Sales."
- Create a new column next to each dollar figure. Label it "% of Revenue."
- Divide each line item by total revenue and multiply by 100.
- Check that gross profit percentage plus cost of goods sold percentage equals exactly 100% at the gross profit level.
- Repeat for additional periods if you want trend data.
That is the entire process. The only judgment call is whether to use net revenue or gross revenue as the base. For most industrial and consumer companies, net revenue is correct. For financial companies like banks and insurers, analysts often substitute total interest income or net premiums earned, since "revenue" has a different meaning in financial services.
Reading the Common Size Income Statement: What the Numbers Tell You
The percentages become meaningful once you know the benchmarks for the sector you are analyzing.
Gross margin above 60% typically signals a software, pharmaceutical, or consumer brand business where intellectual property or branding creates pricing power. Gross margin below 20% is normal for retail and distribution where the business model runs on volume.
Operating margin above 20% is strong in most sectors. Microsoft sits near 45% operating margin, driven by the high-margin cloud and software mix. A manufacturing company at 12% might be equally well-run for its category.
SG&A as a percentage of revenue is a cost-discipline signal. If a company's SG&A grows faster than revenue year over year, the common size statement shows that immediately. The percentage climbs while revenue stays at 100%.
Net margin is the final efficiency score. Apple's net margin runs around 24.6%. Walmart's runs near 2.4%. Neither is wrong: they reflect entirely different business models. Common size analysis keeps you from mistaking Walmart's low net margin for a problem.
Comparing Companies with Common Size Statements
The format's strongest use case is direct peer comparison. Below is a simplified comparison between a technology-style business and a retail-style business at the same revenue:
| Line Item | Tech Company (% Rev) | Retail Company (% Rev) |
|---|---|---|
| Revenue | 100.0% | 100.0% |
| Cost of Goods Sold | 28.0% | 74.0% |
| Gross Margin | 72.0% | 26.0% |
| SG&A | 18.0% | 16.0% |
| R&D | 12.0% | 0.5% |
| Operating Margin | 42.0% | 9.5% |
| Net Margin | 31.0% | 5.8% |
The tech company spends 12% of revenue on R&D and still delivers 31% net margin. The retail company spends almost nothing on R&D and delivers only 5.8%. The cost structure difference is invisible in raw dollar terms when revenues are equal. The common size statement makes it obvious.
Common Mistakes When Using This Format
The most frequent error is treating a low margin percentage as automatically bad. A 3% net margin at Costco reflects a deliberate low-margin, high-turnover model that generates exceptional return on assets. Context matters.
The second mistake is comparing across industries without adjusting for typical margin ranges. A 15% operating margin is outstanding for a supermarket chain and mediocre for a software company. Always compare common size percentages within the same sector.
The third mistake is ignoring non-operating items. Interest expense, one-time gains, and tax rate variations all appear in the common size statement but are not part of core operating performance. If a company's net margin jumps because of a tax benefit rather than improved operations, the common size table will show operating margin flat while net margin spikes. That divergence is a signal worth investigating.
Using ValueMarkers to Run Common Size Analysis
You do not need to build spreadsheets manually for every company you analyze. The ValueMarkers screener surfaces net margin, gross margin, and operating margin for over 6,000 companies across 73 global exchanges. You can filter by margin threshold, sort by margin trend, and cross-reference with ROIC and ROA in the same view.
The VMCI Score on each company profile weights Quality at 30% of the overall score, and margin consistency feeds directly into that Quality pillar. A company holding 20%+ net margins across five consecutive years scores substantially higher on Quality than one with volatile margins, even if the five-year average looks similar.
Further reading: SEC EDGAR · Investopedia
Why common size analysis Matters
This section anchors the discussion on common size analysis. The detailed treatment, formula, and worked examples appear in the body of this article above. The points below summarize the most important takeaways for value investors who want to apply common size analysis in real portfolio decisions. ValueMarkers exposes the underlying data on every covered ticker via the screener and stock profile pages, so the concepts in this article translate directly into actionable filters.
Key inputs for common size analysis
See the main discussion of common size analysis in the sections above for the full treatment, including the inputs, the calculation methodology, the typical sector benchmarks, and the most common pitfalls to avoid. The ValueMarkers screener lets value investors filter the full universe of 100,000+ stocks across 73 exchanges using common size analysis alongside the rest of the 120-indicator composite, with sector percentiles and historical trends shown on every stock profile.
Sector benchmarks for common size analysis
See the main discussion of common size analysis in the sections above for the full treatment, including the inputs, the calculation methodology, the typical sector benchmarks, and the most common pitfalls to avoid. The ValueMarkers screener lets value investors filter the full universe of 100,000+ stocks across 73 exchanges using common size analysis alongside the rest of the 120-indicator composite, with sector percentiles and historical trends shown on every stock profile.
Related ValueMarkers Resources
- Net Margin — Glossary entry for Net Margin
- Roe — Glossary entry for Roe
- Roa — Glossary entry for Roa
- Income Statement Explained — related ValueMarkers analysis
- How To Read An Income Statement — related ValueMarkers analysis
- Yield Curve Inversion What It Means For Stocks — related ValueMarkers analysis
Frequently Asked Questions
what happens if the stock market crashes
A stock market crash typically compresses valuations across all sectors, but companies with strong margins and cash-rich balance sheets recover faster than those running thin margins. Common size analysis helps you identify businesses with durable cost structures before a crash, specifically those where gross and operating margins have stayed stable across previous downturns. In the 2020 COVID crash, Apple's high gross margin (near 38% at the time) allowed it to recover to pre-crash levels within five months.
what time does the stock market open
U.S. stock markets (NYSE and Nasdaq) open at 9:30 a.m. Eastern Time on weekdays, excluding federal holidays. Pre-market trading begins as early as 4:00 a.m. Eastern on most brokerage platforms, though volume and liquidity are much thinner outside regular hours. For international exchanges covered by ValueMarkers, open times vary by time zone.
what time does the stock market close
U.S. stock markets close at 4:00 p.m. Eastern Time. After-hours trading extends to 8:00 p.m. Eastern on most retail brokerages. The official closing price used in index calculations and end-of-day financial data is set at the 4:00 p.m. auction, not during extended hours.
why is the stock market down today
The stock market moves on a combination of macroeconomic data (inflation reports, employment figures, Federal Reserve statements), corporate earnings surprises, and broad risk-sentiment shifts. On any given day, a single large earnings miss or a surprise Fed comment can move the major indices by 1-2%. For context, the dow jones swings roughly 6.1 points per $1 move in any constituent stock, which means five large stocks moving together can swing the index 200+ points.
what time does stock market open
NYSE and Nasdaq open at 9:30 a.m. Eastern Time, Monday through Friday. The London Stock Exchange opens at 8:00 a.m. GMT. The Tokyo Stock Exchange opens at 9:00 a.m. JST with a midday break from 11:30 a.m. to 12:30 p.m. ValueMarkers tracks companies across all three of these exchanges and 70+ others globally.
is coca cola a good stock to buy
Coca-Cola (KO) trades at a P/E near 23.7 and yields approximately 3.0% with over 60 consecutive years of dividend growth. Its common size income statement shows a gross margin near 60% and a net margin near 22%, both exceptionally stable across economic cycles. Whether it is a "good buy" depends on your entry price relative to intrinsic value. At current levels, KO looks fairly valued by most DCF models, meaning the dividend yield compensates for slow growth but leaves limited upside for capital appreciation.
Run the full income statement margin analysis on any stock you are researching at ValueMarkers Screener, where gross margin, operating margin, and net margin appear alongside 120+ additional indicators.
Written by Javier Sanz, Founder of ValueMarkers. Last updated April 2026.
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Disclaimer: This content is for informational and educational purposes only and does not constitute investment advice, a recommendation, or an offer to buy or sell any security. Past performance does not guarantee future results. Consult a licensed financial advisor before making investment decisions.