When adding a document, either the initial or the total price of each product/service is already known to the app. This depends on which one your used when adding said products/services.

## Setup a calculator mode for ALL documents

If you want to apply a specific calculation method as default for all of your documents, you can do so from the **Settings -> Application settings **page.

On the **"Default value calculation mode"** field, select between totals and initial values.

This setting will apply to Bids, Sales / Purchasing Documents, and Recurring Documents. You can change this for each document individually as you will see in the next paragraph.

## Setup a calculator per document

To choose how you want the calculations to be made inside a specific document, just click on the **Settings** button located at the top-left of the Products / Services section when adding/editing.

As an example, initially, we will calculate the values for a document including a single product/service, multiplied by 10, based on the total price and then calculate the values of the document for the same product/service in the same amount, but based on the initial value.

**Value calculations based on totals**

Let us assume that the product’s total value is known, equal to 9,99 and wish to apply a VAT rate of 20%. The value of this particular product/service is displayed on the image below.

Since you wish the product/services quantity to be 10, the total value of the document occurs as follows:

**Value calculations based on initial value **

In the above scenario, values were calculated based on the totals values of products/services. In some cases, however, the product/services initial value is known to us.

Let us assume you wish to calculate the last document's total amount based on the initial values of product/services. After you select the initial value calculation method, as described above, the new values are automatically calculated upon the document. In the image below the new values can be seen, as occurred based on initial value.

The document’s total amount is now calculated as the **total initial value** of existing products/services (remember that unit's initial value is 8,325), plus taxes.