GST Calculator

Goods and services tax is a single tax applied to most supplies of goods and services. Adding it multiplies the base price; removing it divides, and the same rate can be split between national and regional shares.

AmountThe base price, or the GST-inclusive total if you are extracting tax.GST rate(%)The applicable GST rate as a percentage.Direction (1 = add, 0 = remove)Use 1 to add GST to a base, 0 to extract it from a total.

GST-inclusive total

$550.00

Base price: $500.00
GST amount: $50.00

Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.

The formula this calculator uses

GST = base x rate

base: Price before GST
rate: GST rate as a decimal, such as 0.10 for 10%
gst: The tax amount, base times rate
total: Base plus GST

How to check the result by hand

1
Confirm the rate
Check the standard rate for the jurisdiction and whether any split applies between national and regional shares.
2
Identify the base price
If you have a GST-inclusive figure, divide it by one plus the rate first to recover the base.
3
Multiply to get the tax
Multiply the base by the rate. A 500 base at 10% gives 50 of GST.
4
Add for the total
Add the tax to the base to get what the customer pays. 500 plus 50 is 550.
5
Reverse the calculation if needed
Given a total, divide by one plus the rate to recover the base rather than subtracting the rate from the total.

For worked examples, common mistakes and the limits of this formula, read the full How To Calculate GST page.