Add or remove GST/VAT from any amount instantly.
Whether you need to add tax to a pre-tax price or work backward to find the pre-tax price from a tax-inclusive total, this calculator handles both directions with a single tax-rate input. It works for GST (India, Australia, New Zealand, Canada, Singapore), VAT (UK, EU), sales tax (US), or any percentage-based consumption tax regardless of what your country calls it or what rate applies — the underlying math is the same everywhere, only the label and rate differ.
Enter the amount and tax percentage, choose whether to add or remove tax, then tap Calculate.
To add tax, multiply the pre-tax amount by the rate: 18% GST on 1,000 is 180, so the total is 1,180. To remove tax from a tax-inclusive total, divide by (1 + rate): 1,180 ÷ 1.18 = 1,000, which leaves 180 of tax. This is called a reverse or inclusive calculation, and it is the one most people get wrong.
Do not subtract 18% from 1,180. That gives 967.60, because 18% of the tax-inclusive total is 212.40, not the real tax of 180. The tax was calculated on the pre-tax price, so you must divide by 1.18 to undo it. The Remove mode in this tool applies the correct method every time.
Enter whatever rate applies in your region. Rates and rules vary by country, product type and registration status, and some goods are zero-rated or exempt, so confirm the correct rate with your tax authority or accountant. Once you have the numbers, the Invoice Maker can produce a clean invoice, and the Discount Calculator helps when a sale price and tax both apply.
What's the difference between adding and removing tax?
"Add" treats your amount as the pre-tax price and calculates the tax-inclusive total. "Remove" treats your amount as already including tax and extracts the original pre-tax price.
Does this work for any country's tax rate?
Yes — enter whatever percentage applies in your region; the math is the same regardless of what the tax is called locally.
What is reverse GST calculation?
"Reverse" GST means working backward from a tax-inclusive total to find the original pre-tax amount and the tax portion within it — exactly what "Remove" mode does here. It's the calculation freelancers and small businesses most often need when a client payment or invoice total already includes tax and they need to know the pre-tax value for their own records.
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