How Do You Calculate GST Backwards

To find the price before GST, you divide the total price by 1.15.

Formula:

Price before GST = Total price ÷ 1.15

Example:
If something costs $230 (with GST),

230 ÷ 1.15 = 200

So, the price before GST is $200, and the GST part is $30.

How to Add 15% GST

If you want to add GST to a price, multiply the price by 1.15.

Formula:

Price with GST = Price before GST × 1.15

Example:

$200 × 1.15 = $230

So, $230 is the total price including GST.

How to Calculate GST in Excel

You can easily find or remove GST in Excel.

TaskExcel FormulaExample
Remove GST (find price before GST)=A1/1.15If A1 = 230 → 200
Find GST part only=A1-(A1/1.15)If A1 = 230 → 30
Add GST (15%)=A1*1.15If A1 = 200 → 230

Use a GST Calculator

  • If you don’t want to do maths, you can use a GST Calculator NZ.
  • Just enter your price — it will show you the GST amount, price before GST, and price after GST instantly.

How to Add GST to a Price in NZ

To add GST, simply multiply your base price by 1.15.
For example,

$100 × 1.15 = $115
The extra $15 is the GST.

Excel Formula to Remove GST NZ

To remove GST in Excel, use:

= TotalPrice/1.15

This gives you the price before adding GST.

FAQs

How do you calculate reverse GST?

Divide the total (GST included) by 1.15 to get the price before GST.

How do you calculate GST backwards in NZ?

Use the formula: Total ÷ 1.15.

How do I work out GST backwards?

Find the GST-free price first (Total ÷ 1.15), then subtract that from the total to get the GST part.

What is the formula for calculating GST from total?

Exclusive Price = Total ÷ (1 + GST rate).
For NZ, that’s Total ÷ 1.15.

Summary

  • GST in NZ is 15%.
  • To remove GST, divide by 1.15.
  • To add GST, multiply by 1.15.
  • You can also use a GST calculator or Excel formulas to make it easier.