Free tool

GST and QST calculator

Enter an amount: the GST, the QST and the total are calculated to the cent. The other way round, find the pre-tax amount of a total.

DirectionAdd taxesRemove taxes

Amount before taxes ($)

Rates in effect in Quebec: GST 5%, QST 9.975% (checked in October 2026).

Amount before taxes: $100.00
GST (5%): $5.00
QST (9.975%): $9.98
Total: $114.98

Everything runs in your browser. Nothing is sent, nothing is stored.

Do you do this every week? I can automate it.

Twenty minutes on the phone to look at how you do it today, and what could run on its own.

Book 20 minutes

Frequently asked questions

How are the GST and QST calculated?

Both taxes are calculated on the amount before taxes: GST = amount × 5%, QST = amount × 9.975%. The QST is not calculated on an amount that already includes the GST. Each tax is rounded to the cent.

How do I remove the taxes from a tax-included amount?

Divide the total by 1.14975, that is 1 plus 5% plus 9.975%. For example, $114.98 ÷ 1.14975 = $100.00 before taxes, including $5.00 of GST and $9.98 of QST.

Why is there sometimes a one-cent gap?

Because each tax is rounded on its own. Some totals cannot come exactly from an amount to the cent: the tool tells you when that happens.

Free tools