GST/QST Calculator for Canada

Calculate the federal GST (5%) and Quebec QST (9.975%) on a purchase amount, or work backward from a tax-included total, using the standard combined 14.975% rate applied to the pre-tax price.

Quick Facts

GST rate
5% federal
Applies across Canada on most goods and services.
QST rate
9.975% (Quebec only)
Quebec Sales Tax, in effect since January 1, 2013.
No tax-on-tax
QST applies to the pre-tax price
Since 2013, QST is calculated on the selling price, not the GST-included amount.

Your Results

Calculated
GST (federal)
-
5% federal Goods and Services Tax
QST (Quebec)
-
9.975% Quebec Sales Tax on the pre-tax amount
Total tax
-
GST + QST combined (14.975%)
Total amount (tax included)
-
Pre-tax amount plus GST and QST

Ready

Enter an amount, choose a direction, and press Calculate.

How the GST/QST Calculator for Canada works

Quebec is the only province that layers a provincial sales tax, the Quebec Sales Tax (QST), on top of the federal Goods and Services Tax (GST). This calculator applies the standard combined-tax formula used in Quebec retail and invoicing: GST at 5% and QST at 9.975%, both calculated on the pre-tax selling price.

The formula

For a pre-tax amount A:

GST = A × 5%
QST = A × 9.975%
Total tax = GST + QST = A × 14.975%
Total price = A + Total tax = A × 1.14975

Since January 1, 2013, QST has been calculated on the selling price before GST, not on the GST-included price — there is no tax-on-tax. To work backward from a tax-included total T, divide by the combined rate: A = T / 1.14975, then apply the GST and QST formulas to that recovered pre-tax amount.

Worked example

A $100.00 purchase in Quebec: GST = $100 × 5% = $5.00. QST = $100 × 9.975% = $9.975, which rounds to $9.98. Total tax = $14.975 ≈ $14.98. Total price = $114.98. Starting instead from a $114.98 receipt total and dividing by 1.14975 recovers the same $100.00 pre-tax amount.

What changes the result

  • Direction: "Amount excludes tax" adds GST and QST on top of what you entered; "Amount includes tax" extracts them from a total you already paid.
  • Rate overrides: the GST and QST rate fields default to the current 5% and 9.975% rates but can be adjusted for a hypothetical rate change or a zero-rated/exempt item that follows different rules.
  • Rounding: retailers round each tax line to the nearest cent, so totals calculated across a basket of individually-taxed items can differ by a cent or two from tax applied once to the basket subtotal.

Where this applies

GST applies nationwide; QST applies only within Quebec. Other provinces combine GST with a separate Provincial Sales Tax (PST) or use a single blended Harmonized Sales Tax (HST) rate — both work differently from the GST/QST calculation modeled here, so this tool is specific to Quebec transactions.

Frequently Asked Questions

How is GST and QST calculated in Quebec?
GST is 5% of the pre-tax amount, and QST is 9.975% of that same pre-tax amount, not the GST-included total. Combined, GST plus QST equals 14.975% of the pre-tax price. For example, a $100 purchase carries $5.00 GST and $9.98 QST (9.975% rounded to the cent), for a total of $114.98.
Is QST calculated on top of GST?
No. Since January 1, 2013, QST has been calculated only on the selling price before GST, not on the GST-included amount. Before that date QST was compounded on the GST-included price, which produced a slightly higher effective rate.
How do I find the pre-tax price from a total that already includes tax?
Divide the tax-included total by 1.14975 (1 plus the combined 14.975% rate) to recover the pre-tax amount. Subtracting that pre-tax amount from the total gives the combined GST and QST. Choosing "Amount includes tax" in this calculator does that division automatically.
Does GST/QST apply to every purchase in Quebec?
Most goods and services are taxable, but some categories such as basic groceries, prescription drugs, and certain medical devices are zero-rated or exempt. This calculator assumes the entered amount is fully taxable at the standard rates; adjust the GST and QST rate fields if a specific item follows different rules.

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