GST / Sales Tax Calculator
How it works
Add tax treats what you entered as the price before tax and adds the rate on top. Remove tax treats it as a total that already includes tax, and works backwards to the price before it.
The second direction is the one worth being careful about. To take 18% tax out of a total of 1,180 you divide by 1.18 to get the 1,000 base — subtracting 18% of 1,180 would leave 967.60, which is wrong by more than 3%. The larger the rate, the wider that gap.
Working with plain percentages rather than tax? The percentage calculator covers increases, decreases and "what percent of" questions.
Frequently asked questions
How do I find the tax inside a total?
Choose "Remove tax". The tax inside a tax-inclusive price is not that percentage of the total — at 18%, the tax inside 118 is 18, not 21.24 — so the base has to be recovered first by dividing by 1.18.
Does this work for GST, VAT and sales tax?
Yes. All three are a percentage added to a price, so the arithmetic is identical; only the name and the rate differ. Type whichever rate applies to you.
How do I split GST into CGST and SGST?
Halve the tax amount. An 18% GST is levied as 9% CGST and 9% SGST, so each half is exactly half the tax figure shown above.