The Fathom formula builder allows you to build out mathematical equations that calculate the values of the cells in the Fathom main grid. This is a fantastic tool that allows you to acknowledge the relationship between P&L accounts. For example, you may wish to represent your commissions expense account as 10% of sales in your forecast. The Fathom formula builder allows you to create these formulas and incorporate drivers.

You can use any chart of account line item, sub total, heading, driver or typed value, combined with the 4 operators and parentheses to build out formulas for any chart of account line item on the Profit & Loss.

### Create a Formula/Driver Value Rule

To create a new formula or edit an existing one:

- Click into the value cell for the account you wish to apply the formula.
- Selecting the ‘three dot’ icon allows you to add a new rule or edit an existing rule.
- Once you enter the rule editing pane, select ‘Formula/Drivers’ to open the Formula editor.

Formulas can be edited or overridden at any point, by opening the properties panel to the right of an account and using the pencil ‘Edit Formula’ account. This can then be applied across a whole range of accounts, to help you build your most accurate forecast.

**Drivers **can be set up from the Fathom main grid and are essentially ‘non-financial’ metrics or leading indicators that are used to calculate the value of accounts.

*For example, you could set up and import data for two drivers: ‘Number of Units Sold’ and ‘Average Sales Price’. Using a formula you would then be able to reference these drivers to compute the value of the ‘Sales’ account as ‘Number of Units Sold’ x ‘Average Sales Price’. *

*100 * $30,00 = 30,000 for the month of August 2020. *