GST Calculator
Add or remove GST from any amount. See the base, tax, and total instantly. Free, accurate, and private.
Calculator by Toolsloft ↗- Base amount
- $1,000.00
- GST
- $180.00
- Total
- $1,180.00
This calculator adds GST onto a pre-tax amount or removes it from a GST-inclusive price, showing the base, the tax, and the total. Use it to price goods with tax on top, or to back out the tax already baked into a quoted figure.
How this is calculated
In add mode the tax is amount times rate divided by 100, added to the base; in remove mode the base is amount divided by (1 plus rate divided by 100) and the tax is the difference, with results rounded to two decimals.
How to use
- Enter the amount.
- Set the GST rate (e.g. 18) and choose Add or Remove.
- Read the base, tax, and total.
Examples
- Add 18%:
1000 → tax 180, total 1180 - Remove 18%:
1180 → base 1000, tax 180
FAQ
- What is the difference between adding and removing GST?
- Add treats your amount as the pre-tax base and adds GST on top. Remove treats your amount as GST-inclusive and extracts the base and tax from it.
- How is GST removed from an inclusive price?
- Base = amount ÷ (1 + rate/100), then tax = amount − base. For 1180 at 18%, the base is 1000 and the GST is 180.
- Are results rounded?
- Yes, to two decimal places using standard half-up rounding, the convention for currency.