Formula Fields

A Formula field is a type of custom field, whose value is automatically computed by based on a formula or conditional logic. It enables users to define complex data manipulations and perform arithmetic, logical or conditional operations, which are all calculated at run-time.
Let us take an example:

Say your business practice is to take 10% of the project budget as an advance. Instead of manually computing it and changing it every time the budget changes, you would define a formula field that will compute it as 10% of the budget. To further complicate the scenario, let us assume that your policy is to take an advance of 10% for projects with budget up to $1000 and 15% above that. You can define such a formula and avoid chances of errors in manually computing this field. The formula would be

${me.budget <= 1000 ? me.budget * 0.10 : me.budget * 0.15}

For a project with a budget of $500, the advance amount will show $50 (10% of $500) while that for a budget of $5000 will show $750 (15% of $5000). If you change the policy, just change the formula and the new value will show up for all projects.

Except for the fact that you cannot enter a value for formula fields they are identical to the other custom fields. These fields can be viewed in tabular reports or charts and used for filtering report results.