Common-Size Financial Statements

By Ryan O'Connell, CFA, FRM Published November 5, 2026

A company’s expenses can rise while consuming a smaller share of sales. Its profit margin can improve while its profit dollars fall. Common-size financial statements make those distinctions easier to see by expressing statement amounts as percentages of a clearly identified base.

This guide uses one hypothetical manufacturer across three years to connect vertical analysis, horizontal changes and base-year indexes. The examples use simplified U.S. accounting terminology. The goal is to identify what changed, then determine which accounting notes and business explanations you need before drawing a conclusion.

What Are Common-Size Financial Statements?

A common-size statement expresses financial amounts relative to a common base. In conventional vertical analysis, an income statement uses revenue as 100%, while a balance sheet uses total assets as 100%. This reduces the effect of company size when comparing statement composition across periods or businesses.^[1]

Common sizing complements financial ratio analysis: it applies one denominator throughout a statement, whereas selected ratios use different relationships to investigate profitability, liquidity, leverage or efficiency.

The Vertical Analysis Formulas

These are the bases used throughout this article. Other analytical presentations can choose different denominators, so inspect the label before comparing percentages.^[1] The conventional revenue and asset bases are also illustrated in OpenStax’s common-size lesson.^[3]

Common-Size Income Statement Example

Consider Ridgeway Components, a fictional manufacturer. Its hypothetical historical income statements cover full years ending December 31, 2023, 2024 and 2025. All amounts below are in USD thousands; each cell shows the amount followed by its percentage of that year’s revenue. These are observed results within the example, rather than projections.

Assume consistent accounting policies and classifications, no acquisitions and no other income or expenses. Cost of goods sold and selling, general and administrative expense (SG&A) exclude the depreciation shown separately. Expenses appear as positive amounts to deduct. Income tax is stipulated at 25% of pretax income solely to keep the example transparent.

For FY2024, the operating subtotal is $1,200 − $696 − $288 − $60 = $156 thousand. Common sizing converts that to $156 / $1,200 × 100 = 13%. Interest and tax then reduce net income to $156 − $24 − $33 = $99 thousand, or 8.25% of revenue.

The cost structure changed as sales grew: COGS fell from 60% to 58% of revenue in FY2024, while SG&A fell from 25% to 24%. Depreciation remained 5%. Together, those movements explain operating margin rising from 10% to 13% within this simplified statement. For the distinctions among the profit subtotals, see gross, operating and net profit margins.

Percentage Changes vs. Percentage-Point Changes

Three different calculations describe Ridgeway’s FY2023-to-FY2024 operating improvement:

• Margin change: 13% − 10% = 3 percentage points.
• Relative increase in the margin: (13 − 10) / 10 × 100 = 30%.
• Growth in operating-income dollars: ($156 − $100) / $100 × 100 = 56%.

The first measures the distance between two percentages. The second measures that distance relative to the starting margin. The third measures profit growth, reflecting both sales growth and the higher margin. Label the measure explicitly whenever reporting a change.

Keep subtotals separate from components. Gross profit, operating income and net income are successive results after deductions. They are not independent slices of revenue to add together. COGS plus gross profit equals revenue here; COGS plus gross profit plus operating income does not form a meaningful whole.

Common-Size Balance Sheet Example

Ridgeway’s next table shows balances as of December 31 in each year. A balance sheet measures assets and obligations at a particular date; the income statement measures revenue and expenses over a period.^[2] Use each date’s total assets as the denominator, rather than that year’s revenue.

The same hypothetical business has only the accounts listed below. Each cell again combines a USD-thousands amount with its common-size percentage. Current assets include cash, receivables and inventory; current liabilities include payables and current debt. Net property, plant and equipment (PP&E) is shown after accumulated depreciation.

For FY2024, receivables represent $180 / $1,000 × 100 = 18% of total assets. The balance sheet reconciles as $540 current assets + $460 net PP&E = $1,000 assets = $500 liabilities + $500 equity. The accounting equation also holds in FY2023 and FY2025.

For full consistency, the example includes a $20 thousand capital contribution and $19 thousand dividend in FY2024, followed by a $49.1 thousand dividend in FY2025. With no other equity changes, retained earnings moves from $100 to $100 + $99 − $19 = $180 thousand, then to $180 + $89.1 − $49.1 = $220 thousand. The three financial statements guide explains these profit, equity and cash connections.

How to Interpret the Asset and Financing Mix

Receivables rise from 15% to 20% of assets across the three dates, while net PP&E falls from 50% to 45%. That describes a shift in the asset mix. PP&E still increases in dollars, from $400 to $486 thousand; its share falls because total assets grow faster.

Liabilities and equity each remain 50% of assets, but the detailed financing components move. In FY2024, interest-bearing debt is $44 + $300 = $344 thousand, or 34.4% of assets. Total liabilities are higher at 50% because they also include $156 thousand of trade payables. State whether a leverage measure includes all liabilities or only interest-bearing debt.

Asset components total 100% on the asset side. Liabilities plus equity total a separate 100% on the financing side. A subtotal such as current assets overlaps its cash, receivables and inventory components, so adding all displayed rows would double count. The balance-sheet percentages are based on reported accounting amounts; they do not establish the market value of the business.

Horizontal Analysis: Dollar and Percentage Changes

Vertical analysis describes composition. Horizontal analysis compares the same line across reporting periods. It is useful to retain both the dollar change and the percentage change: one shows the amount at stake, while the other scales it to its starting level.^[4]

Apply those calculations to selected Ridgeway lines. Each year’s change below uses the preceding year, so FY2024 is compared with FY2023 and FY2025 with FY2024. Dollar changes are in USD thousands; percentages are rounded to two decimals.

For revenue in FY2025, $1,080 − $1,200 = −$120 thousand and −$120 / $1,200 × 100 = −10%. Meanwhile, receivables rise 20%. That divergence is a reason to investigate customer credit, collection timing, seasonal sales and other receivable movements. It does not establish a collection problem by itself. See working capital management for the operating cycle behind those questions.

Base-Year Indexes: Comparing Several Years

For a longer comparison, keep one fixed base year instead of resetting to the previous year. Give each line its own starting amount an index value of 100. An index of 120 then means that line is 20% above its base-year amount.

Return to Ridgeway and set FY2023 = 100 for revenue, receivables and total assets. The first series represents annual sales; the other two represent the December 31 balances. The chart compares their proportional paths over equally spaced years, using each series’ own starting amount.

Receivables finish 80% above their base-year level, while revenue is only 8% above its base. The index makes that widening difference visible, although explaining it still requires the supporting business information.

For example, the FY2025 revenue index is $1,080 / $1,000 × 100 = 108. Its decline from 120 to 108 is 12 index points; the year-over-year decline is (108 − 120) / 120 × 100 = −10%. A fixed-base index of 108 therefore does not mean sales grew 108% or grew 8% during FY2025.

Denominator Effects: Better Percentages, Lower Dollars

Ridgeway’s FY2025 gross margin improves from 42% to 44%, even though revenue falls 10%. Gross profit declines from $504 to $475.2 thousand, a $28.8 thousand decline, because the higher margin applies to a smaller sales base. At the operating level, SG&A takes a larger revenue share, leaving operating margin unchanged at 13% and operating-income dollars down 10%.

This is why a percentage improvement should be checked against its numerator and denominator. A lower cost share might reflect lower spending, faster revenue growth, a different product mix or a reporting change. The percentage alone cannot distinguish those explanations.

As a separate hypothetical example in dollars, hold a cost fixed at $100 while revenue shrinks from $1,000 to $800. Its revenue share rises from $100 / $1,000 = 10% to $100 / $800 = 12.5%, even though spending is unchanged. This is a denominator effect, rather than evidence that the company spent more on that cost.

Zero, Negative and Very Small Bases

The growth formula needs extra care when the starting amount is zero, negative or tiny. The following independent hypothetical cases use dollars and illustrate the problem; they are separate from Ridgeway’s statements.

Fixed-base indexes have the same zero-base problem, and negative bases make their usual growth interpretation unreliable. Label such results as not meaningful where appropriate and retain the underlying amounts; changing the denominator to its absolute value silently creates a different measure.

A negative line item does not automatically invalidate vertical analysis. A net loss of −$10 on $100 of positive revenue gives a valid −10% net margin. Negative equity divided by positive assets can likewise be shown. The denominator and economic meaning need attention: zero revenue makes revenue-based percentages undefined, while unusually small or negative revenue may make conventional margin interpretation unhelpful.

Vertical Analysis vs. Horizontal Analysis and Forecasting

A multi-year common-size income statement uses both perspectives: each column contains vertical percentages, and comparing those columns reveals changes in composition over time. Some references also call fixed-base indexing “horizontal common-size analysis.” Always name the denominator and base period so the terminology does not obscure the calculation.

Forecasting adds assumptions. Calculating historical COGS as 56% of revenue describes Ridgeway’s FY2025 result. Assuming COGS will remain 56% of future revenue is a separate prediction about costs and sales. Historical shares can inform a model, but they do not prove that all costs or balance-sheet accounts scale with revenue. See pro forma financial modeling for the forecasting task.

How to Analyze Common-Size Statements

1. Define the question. Decide whether you are investigating cost structure, asset allocation, financing or growth. Keep the dollar statements available.
2. Match the inputs. Use the same reporting entity, currency, units and accounting basis. Check fiscal-year length, year-end dates and any restated or reclassified comparative columns.
3. Calculate the vertical percentages. Divide each income-statement line by same-period revenue, and each balance-sheet line by same-date assets. Check the relevant identities without adding overlapping subtotals.
4. Calculate horizontal movements. Retain dollars and percentages, flag problematic bases, and choose explicitly between prior-year changes and one fixed-base index.
5. Investigate the important divergences. Relate margin shifts to the cost lines, and compare receivable or inventory growth with operating activity. Read notes and management’s explanations before assigning a cause.
6. Follow up with other evidence. Examine liquidity, turnover and cash generation. The Financial Ratio Calculator can help with selected follow-on ratios; common sizing by itself is not a cash-flow assessment.

For SEC reporting companies, MD&A is a useful next stop: Item 303 calls for the underlying reasons for material line-item changes and, where applicable, explanations of revenue changes attributable to price, volume or new products.^[6] The calculation directs your attention; the supporting disclosure helps explain the movement.

Comparability Checks and Limitations

Acquisitions and Changes in the Business

An acquisition can change the consolidated asset mix, introduce goodwill and acquired intangible assets, and add revenue from the acquired business. A late-year acquisition can place the acquired business’s assets on the closing balance sheet while contributing only part of a year’s results. Compare consolidation scope and acquisition timing before interpreting asset growth against sales growth.

As a historical illustration, Microsoft’s FY2024 annual report states that Activision Blizzard’s results were included from the acquisition date. Its acquisition discussion also describes allocating purchase price to acquired assets and assumed liabilities.^[8] Read actual transaction disclosures and any clearly labeled comparable information; a percentage conversion cannot reconstruct a missing full-year comparison.

Reclassifications and Accounting Policies

Moving an expense from SG&A to COGS changes gross margin even if total expense and operating income stay the same. A change in inventory accounting or a depreciation estimate can also affect comparability. For reports prepared under IFRS or another framework, check the accounting policies before comparing their percentages with a U.S. report. Inspect the notes, including changes in presentation, instead of assuming every percentage movement reflects a change in business performance.^[2]

Use comparable figures supplied in the latest report and document their basis. Distinguish a classification change from a change in accounting principle or an error correction; the PCAOB’s consistency standard expressly treats these as issues requiring evaluation.^[5] The inventory valuation methods guide provides context for one accounting-policy difference.

Inflation, Currency and Period Length

Nominal revenue growth may come from higher prices, increased volume or a different sales mix. Common-size percentages and base-year financial indexes do not automatically remove inflation. A suitable price adjustment is a separate analytical step: BLS explains that price indexes can deflate dollar series and that the appropriate inflation measure depends on the intended use.^[7] Consumer CPI is not automatically the right measure for a manufacturer’s costs or selling prices.

Currency translation, a 53-week fiscal year, a short transition period or a different seasonal balance-sheet date can also distort comparisons. Match comparable quarters or full years where possible and explain the remaining differences. Common sizing a three-month income statement does not turn it into a full-year result.

Business Models, Cash and Causation

A manufacturer that owns equipment and a business that outsources production can have different asset and expense shares for sound economic reasons. Banking and insurance statements also require sector-appropriate definitions. Benchmark against genuinely comparable operations and use consistently defined measures rather than imposing a universal “good” percentage.^[1]

Finally, profitability and asset composition cannot show when cash arrives or whether obligations can be paid. Use the statement of cash flows and free cash flow analysis alongside common sizing. Changes in percentages flag questions; they are not proof of pricing power, efficiency, distress or investment value.

Common Mistakes

• Using the wrong base. Dividing an expense by total expenses answers a different question from dividing it by revenue. Dividing a balance-sheet line by sales is not the conventional total-assets presentation used here.
• Reporting a margin move as ordinary growth. A change from 10% to 13% is 3 percentage points; the margin itself rose 30% relative to its starting level.
• Adding overlapping subtotals. Do not add current assets to cash, receivables and inventory, or add all the profit subtotals together.
• Hiding dollars behind percentages. A smaller asset share can accompany a larger balance, and a higher margin can accompany lower profit.
• Changing the base year midway. A fixed-base index and a year-over-year change have different denominators. Label each column.
• Forcing growth percentages through zero or negative bases. Show the amounts and explain the transition when the ordinary percentage is undefined or misleading.
• Turning a historical share into a forecast without justification. Future cost behavior, capacity and financing need their own assumptions.

Sources

Sources accessed November 5, 2026. Ridgeway Components and all its figures are hypothetical. The Microsoft reference is a dated illustration from its FY2024 annual report.

1. CFA Institute, Financial Analysis Techniques, 2026 Level I curriculum public summary: comparisons, common-size analysis and industry context.
2. SEC, Beginners’ Guide to Financial Statement, February 4, 2007: Balance Sheets, Income Statements, Read the Footnotes and Read the MD&A.
3. OpenStax, Principles of Finance, 5.7: Common-Size Statements, published March 24, 2022: revenue and total-assets denominators.
4. OpenStax, Principles of Accounting, Volume 1, Appendix A: Financial Statement Analysis, published April 11, 2019: Horizontal Analysis and Vertical Analysis.
5. PCAOB, AS 2820: Evaluating Consistency of Financial Statements, paragraphs .01–.06 and .11.
6. eCFR, 17 CFR 229.303: Management’s Discussion and Analysis, paragraphs (b) and (b)(2)(i)–(iii); displayed current through November 3, 2026.
7. BLS, Consumer Price Index Frequently Asked Questions, Using the CPI: deflating dollar series, interpreting indexes and choosing an inflation measure.
8. Microsoft, 2024 Annual Report, fiscal year ended June 30, 2024: MD&A acquisition discussion, Note 1 and Note 8, Business Combinations.