Adding custom formulas to an assembly allows you to have greater control over what is displayed in the final line item on your Reports and in Estimates. Below you will find our most commonly used formula conversions and add-ons.

**More On Item and Assemblies**

Import items into your STACK item database

How to Customize or Create an Assembly

Working with Assembly Formulas

## Topics

## Common Variable Conversions

You may need to convert a takeoff variable into another. Below are examples of common custom variables you can create to convert the data.

### Starting From Count

From [MeasuredCount], add custom variables to represent the other dimensions of the building condition.

Starting from Count | Add Custom Variable (example) |

To Linear Feet | [WallLengthFeet] |

To Square Feet | [WallLengthFeet] and [WallHeightFeet] |

To Cubic Yards | [WallLengthFeet] and [WallHeightFeet] and [WallThicknessInches] |

`[MeasuredCount]*[WallLengthFeet]`

[MeasuredCount]*[WallLengthFeet]*[WallHeightFeet]

[MeasuredCount]*[WallLengthFeet]*[WallHeightFeet]*([WallThicknessInches]/12)/27

### Starting from Linear

From [MeasuredLinear], add custom variables to represent the other dimensions of the building condition.

Starting from Linear | Add Custom Variable (example) |

To Square Feet | [WallHeightFeet] |

To Cubic Yards | [WallHeightFeet] and [WallThicknessInches] |

`[MeasuredLinear]*[WallHeightFeet]`

[MeasuredLinear]*[WallHeightFeet]*([WallThicknessInches]/12)/27

### Starting from Square Feet

From [MeasuredArea] or [MeasuredSurfaceArea], add custom variables to represent the other dimensions of the building condition.

Starting from Square Feet | Add Custom Variable (example) |

To Cubic Yards | [WallThicknessInches] |

`[MeasuredArea]*([WallThicknessInches]/12)`

[MeasuredSurfaceArea]*([WallThicknessInches]/12)/27

## Common Unit Conversion

You may need to convert a takeoff or custom variable from one unit to another. Below are examples of common units and their conversion factors.

### Inches and Feet

From | To | Factor |

Inches | Feet | 12 |

`[WallThicknessInches]/12`

[MeasuredLinear]*12

### Square Feet and Yards

From | To | Factor |

Square Feet | Square Yards | 9 |

`[MeasuredArea]/9`

[CarpetRollYards]*9

### Cubic Inches, Feet, and Yards

From | To | Factor |

Cubic Inches | Cubic Yards | 46656 |

Cubic Feet | Cubic Yards | 27 |

`([MeasuredArea]/12)*([SlabThicknessInches]/12)/46656`

[MeasuredArea]*[SlabThicknessFeet]/27

## Common Formula Functions

### Adding a Waste Percentage

You can add a waste percentage to your formula to control the final quantities. Some examples:

`[MeasuredLinear]*1.10`

[MeasuredArea]*(1+([WastePercentage0to100]/100))

### Evenly-spaced Items

To calculate an item that occurs on set intervals, add a custom variables to represent the distance of the spacing, and then:

`[MeasuredLinear]/[ItemSpacingInFeet]`

[MeasuredLinear]*12/16

[MeasuredLinear]*12/[ItemSpacingInInches]

### Area-coverage Items

When an item is set to a known dimension, we can use that information to convert our area takeoffs into item counts. For example:

`4'x8' sheet of plywood: [MeasuredArea]/32`

4'x10' sheet of drywall: [MeasuredSurfaceArea]/40

### Area of a Circle

To calculate the area of a circle, add a custom variable to represent the radius or diameter of the circle, and then:

`3.14*[RadiusOfCircle]*[RadiusOfCircle] or`

pi()*power([RadiusOfCircle],2)

3.14*([DiameterOfCircle]/2)*([DiameterOfCircle]/2) or

pi()*power([DiameterOfCircle]/2,2)

### Circumference of a Circle

To calculate the circumference of a circle, add a custom variable to represent the radius or diameter of the circle, and then:

`2*3.14*[RadiusOfCircle] or`

2*pi()*[RadiusOfCircle]

3.14*[DiameterOfCircle] or

pi()*[DiameterOfCircle]