> For the complete documentation index, see [llms.txt](https://help.modelreef.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.modelreef.io/syntax/chart-and-table-syntax/common-size-mode.md).

# Common Size Mode

This article explains **common size mode** for charts and tables in Model Reef.

You will learn:

* What common size mode does.
* How it is applied to P\&L, Balance Sheet and Cashflow views.
* When to use it for analysis and communication.

Common size mode expresses series as percentages of a chosen base rather than absolute values.

{% stepper %}
{% step %}

### What common size mode is

In common size mode, values are shown as a proportion of a base metric, for example:

* P\&L lines as a percentage of Revenue.
* Balance Sheet items as a percentage of Total Assets.
* Cashflow lines as a percentage of total cash inflows or outflows.

This makes it easier to compare structure across periods or scenarios, even when absolute sizes differ.
{% endstep %}

{% step %}

### Where common size mode is available

Common size options are typically available in:

* P\&L style charts and tables.
* Balance Sheet views.
* Some Cashflow or Cash Waterfall views where percentage presentation is helpful.

You toggle common size mode via a control on the dashboard or report.
{% endstep %}

{% step %}

### How common size calculations work

When you enable common size:

* Each line item in a period is divided by the base value for that period.
* The result is expressed as a percentage.
* If the base is zero in a period, the behaviour may be to show blanks or zero, depending on implementation.

The underlying absolute values of the model do not change, only the display.

{% hint style="warning" %}
If the base is zero for a period, percentage results depend on the system implementation and may appear as blanks or zeros.
{% endhint %}
{% endstep %}

{% step %}

### Uses of common size analysis

Common size mode is particularly useful for:

* Comparing cost structure between companies or scenarios.
* Tracking margin structure changes over time.
* Understanding how assets and liabilities mix evolves as the business grows.

It can reveal shifts in composition that are not obvious from raw numbers.
{% endstep %}

{% step %}

### Best practice

When using common size mode:

* Always state clearly what the base is (for example "Percent of Revenue").
* Combine with absolute charts elsewhere so users do not lose sense of scale.
* Use it to highlight structure and mix, not as the only view of performance.

Used well, it complements rather than replaces absolute analysis.
{% endstep %}
{% endstepper %}

***

## Related articles

* [Driver Editor Screen](/syntax/understanding-the-interface/driver-editor-screen.md)
* [Economic Driver Fields](/syntax/drivers-syntax/economic-driver-fields.md)
* [Debt Service Logic](/help/financial-outputs-and-valuation/debt-service-logic.md)
* [Build a Bottom Up Forecast](/how-tos/core-modelling/build-a-bottom-up-forecast.md)