Your figures
Result
How this calculator works
Enter an amount and a GST rate, and choose whether the amount already includes the tax. The calculator returns the base amount, the total GST, the invoice total — and, because several GST systems present the tax as two equal components on the same invoice, it also splits the GST into its two halves so you can check an invoice line by line.
The split is presentational, not mathematical: the total tax on the supply is the same whether it is collected under one name or two. Where the distinction bites is in reporting and credits, because the halves may be accounted to different governments and the credit for one cannot always be used against the other. Showing them separately at the calculation stage makes the invoice and the return agree, which is where most GST queries begin.
Good practice and limits
Rates differ by product category and change over time, so treat the rate as an input to confirm, not a constant to memorise. And when you remove GST from an inclusive amount, divide by one plus the rate — subtracting the percentage from the total overstates the base and understates the tax, the same trap as VAT.