In Productive, there is a field for just about everything, but sometimes you have your unique metric or calculation that isn't available by default. 

Luckily, you can use formulas to combine multiple fields into a custom formula field with simple mathematical operations.

To add your formula field, click on Formula > Add Formula.

First, start by giving your new field a name:

Now it's time to add the values you would like to use. To select the first value, type in the "@" symbol - it will show a drop-down menu with a list of available values: 

Select the values you would like to use and combine them as a formula. The following operations are supported:

You can also put your formula in brackets: (A - B) * C 

In this example, we'll create a field that will display the difference between total and remaining budget. The formula used is Budget total (minus) Budget used.

When you're finished, click on Create Field. 

Now, the field is visible in the main view:

Formula fields are available for all numeric data across Productive. 

You can create a composite formula, one that is made of other formulas. For example, the field Total Time is made out of two formulas:

You can use that formula to compose other formulas as well: