GST / Sales Tax Calculator
Add GST or sales tax to a price, or remove it from a tax-inclusive price.
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About the GST / Sales Tax Calculator
Quickly work out tax on an invoice or price tag. Add tax when you have a price before tax and need the total; remove tax when a price already includes tax and you need the net amount and the tax portion — for example to fill in an invoice or check a bill.
It works for GST, sales tax and VAT at any rate. Tax rates differ by country, province and type of goods or services, so check the rate that applies to you.
How to use the GST / Sales Tax Calculator
- Choose Price before tax or Price including tax.
- Enter the amount and the tax rate, or tap a quick rate.
- Press Calculate to see the net price, tax and total.
Formula
- Adding tax: Tax = Net × Rate ÷ 100; Total = Net + Tax
- Removing tax: Net = Total ÷ (1 + Rate ÷ 100); Tax = Total − Net
A common mistake is removing 18% tax by taking 18% off the total. That is wrong: 18% of 11,800 is 2,124, but the actual tax is 1,800.
Examples
- 10,000 + 18% tax = 1,800 tax → 11,800 total.
- 11,800 including 18% tax → net 10,000, tax 1,800.
- 2,500 + 5% tax → 2,625.
Frequently asked questions
What GST rate should I use?
It depends on your country, province and the goods or services. Check the official tax authority or your invoice for the current applicable rate.
How do I find the tax included in a price?
Choose "Price including tax", enter the price and the rate. The calculator divides the price by (1 + rate) to separate the tax.