# How to calculate GST at 15% using Excel formulas

I have been asked twice in one week how to write Excel formulas to calculate GST at the rate of 15%.

You can find information on how to calculate the rate on the NZ Inland Revenue website. I’ve taken this a step further and put together a tutorial on how to put these calculations into Excel formulas.

Let’s start by calculating the GST component of a GST exclusive amount.  To do this you simply multiply the value, ex GST by 15% or by 0.15.  To find the total including GST simply add the two values together.

Let’s now have a look at calculating the total including GST.  This time multiply the total by 115% or by 1.15

Now let’s look at writing a formula to calculate the GST content of a GST inclusive amount.  This formula contains two parts.  First, multiply the GST inclusive amount by 3 and then divide this figure by 23.

In the video tutorial below I show you in Excel how to:

• calculate the GST component to be added to a GST exclusive figure
• calculate the total figure including GST
• calculate the GST component of a GST inclusive figure

The steps in the tutorial will work in Excel versions 2010, 2013 and 2016