---
url: /modelling-guides/creating-a-travel-planning-model/adding-formula-to-cube.md
description: >-
  To complete the Travel model, it will need to calculate Flight Costs,
  Accommodation Costs and Allowances while allowing Transit Expenses to be
  entered manually.
---

# Adding Formula to a Cube (Business Logic)

To complete the Travel model, it will need to calculate **Flight Costs**, **Accommodation Costs** and **Allowances** while allowing **Transit Expenses** to be entered manually.

To open the formula editor right-click on a **Flight Costs** white cell and click **Edit Formula**.

![Creating New Formula](/travel-planning-model-figures/creating-new-formula.png)

Within the Formula Editor, leave the restrictions as they are but copy the formula from below and paste this into the Formula field.

`LINKBY("Travel Rates",["Flight Costs"],LINKDIM("Travel Measures",["Destination"]))*["No People"]`

Click **Save Formula** to apply the formula.

![Formula Editor](/travel-planning-model-figures/formula-editor-flight-cost.png)

Right-click on an **Accommodation Costs** white cell and select **Edit Formula**. Within the Formula Editor, leave the restrictions as they are but copy the formula from below and paste this into the Formula field.

`LINKBY("Travel Rates",["Accommodation Costs"],LINKDIM("Travel Measures",["Destination"]))*["No People"]*["No Nights"]`

Click **Save Formula** to apply the formula.

![Formula Editor](/travel-planning-model-figures/formula-editor-accommodation-cost.png)

Right-click on a **Allowances** white cell and select **Edit Formula**. Within the Formula Editor, leave the restrictions as they are but copy the formula from below and paste this into the Formula field.

`LINKBY("Travel Rates",["Allowances"],LINKDIM("Travel Measures",["Destination"]))*["No People"]*["No Nights"]`

Click **Save Formula** to apply the formula.

![Formula Editor](/travel-planning-model-figures/formula-editor-allowances.png)

All the calculations should now be applied and you can change the **Destination** or other Measures values to test the new calculations.