Formulas in openBoM are equations you create in a cell which performs simple arithmetic operations using the designated cells. The basic principle to understand is that a formula equation needs to reference a specific Part Number along with the chosen property. This document has three topics:

- How formulas work
- Cutting and pasting formulas (
*available soon*) - Formula roll-ups (
*available soon*)

**Note**: Formulas are currently only supported for BOMs, not for inventories.

**How formulas work**

The format for formulas involves referencing the Part Number with properties:

**Target property** = (**Part Number**) (**Property1**) <arithmetic operator> (**Part Number**)(**Property2**)

Let’s see an example:

Let’s say you want to create a formula to calculate the Total Cost of Part Number **100-1**. The formula would consist so: **Total Cost = (100-1)(Quantity) * (100-1)(Cost)**. Here’s what it would look like using the Formula Builder:

In the Formula Builder, as you enter values, you’ll be presented with available Part Numbers and Properties. Here’s another example showing the Total cost formula for **Part Number 100-2**:

**Total Cost** for Part Number 100-2 = (**100-2**)(**Quantity**) * (**100-2**)(**Cost**)

Notice how you access the Formula Builder with a mouse right click in the target property, e.g. Total Cost. Make sure to click **Save** to ensure the formula is applied.

**Pro tip**: Use “@pn” in Formula Builder as a shortcut to replace the current line item Part Number in the formula. Here’s an example:

Arithmetic operators available for formulas are:

**Multiplication (*), Division (/), Addition (+), and Subtraction (-)**

**Copy & paste**

To apply a formula across desired items, you can (1) click “**Apply for all rows**” in the **Formula Builder** window:

or (2) cut and paste formulas across the desired items:

**Formula rollups (summing values in a column)**

To create a formula roll-up, **(1)** click “**Enable Rollup**“. A **(2)** “Totals” row will automatically appear where by you can edit SUMs across all the values in the chosen property (i.e., column).

Here’s a short video showing you how to edit a formula rollup. Currently, only the “SUM” function is available.