> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cfo.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Write your first formula

This guide walks through a simple formula for Gross Profit.

## Before you begin

You need a target property and the properties it will reference. In this example:

* Target property: Gross Profit
* Referenced properties: Revenue and Cost of Goods Sold

## 1. Open the target property

Open **Gross Profit** and go to its formula editor. The formula belongs to Gross Profit because that is the value it calculates.

## 2. Enter the calculation

Write:

```text theme={null}
Revenue - `Cost of Goods Sold`
```

Use the property names shown in cfo.ai. Wrap names that contain spaces, punctuation, operators, or reserved words in backticks.

## 3. Choose where it applies

For a first formula, use the broadest scope so it acts as the default calculation for the property.

You can add more specific formulas later for a segmentation, a segment, Actuals, or Forecast.

## 4. Check the formula

Before saving, confirm that:

* Gross Profit is the target property
* Revenue and Cost of Goods Sold are the intended inputs
* The formula applies in the intended scenario
* The scope is not more specific than you need

cfo.ai validates the syntax and property references when the formula is saved.

## 5. Review the result

Open a table that contains Gross Profit. Check a few periods and, if the table is segmented, a few dimension values.

For example, if Revenue is 100 and Cost of Goods Sold is 40, Gross Profit should be 60.

## Add detail when you need it

Once the default formula works, you can add a more specific formula without changing the default everywhere. Common next steps include:

* Calculate Gross Profit differently for one department
* Use a different formula in Forecast
* Reference another period
* Aggregate several dimension values

Use [Choose where a formula applies](/formulas/core-concepts/choose-where-a-formula-applies) before adding an override.

<Note>
  The source Notion page included an embedded interactive walkthrough (a short HTML walkthrough of this Gross Profit example) that could not be carried over automatically. Consider re-adding it here manually if it's still useful.
</Note>