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The GST amount on a price is 5% of that price, so $250 before tax carries $12.50 of GST and costs $262.50 in Alberta. In an HST province the federal and provincial parts come as one tax, so the same $250 carries $32.50 in Ontario. Here’s how to work the amount out in either direction, and what changes by province.
How do you calculate the GST amount on a price?
Multiply the price before tax by the rate. At 5% that means the price times 0.05. On a $250 invoice you get $12.50, and you add it to reach $262.50.
Going the other way is where people slip. If a receipt shows a total of $105 with GST in it, don’t take 5% of $105. That gives $5.25, which is too much. The CRA’s method is to multiply a tax-included total by 5/105, and here that gives exactly $5.00. Or divide the total by 1.05 to get the $100 price, then subtract.
The GST and HST calculator does the first job, and the reverse tax calculator does the second. Pick the province and both use the current rate.
Which rate applies where you live?
GST is 5% everywhere in Canada. Some provinces then add their own tax on top, or fold theirs into a single HST. This table follows the CRA’s rate page, as we read it in September 2026.
| Where | Federal GST or HST | Provincial tax |
|---|---|---|
| Alberta, Northwest Territories, Nunavut, Yukon | 5% GST | None |
| British Columbia | 5% GST | 7% PST |
| Manitoba | 5% GST | 7% RST |
| Saskatchewan | 5% GST | 6% PST |
| Quebec | 5% GST | 9.975% QST |
| Ontario | 13% HST | Included |
| Nova Scotia | 14% HST | Included |
| New Brunswick, Newfoundland and Labrador, Prince Edward Island | 15% HST | Included |
Nova Scotia dropped from 15% to 14% on April 1, 2025. If you’re looking at an invoice from before that date, the old rate is the one that applied.
What does the same $250 cost in different provinces?
We ran one price through the calculators to show how much the province matters. All amounts are before tax.
Alberta gets $12.50 of GST and a total of $262.50. Ontario’s HST is $32.50, which makes $282.50. Nova Scotia’s is $35.00, so you pay $285.00. Manitoba is the odd one out because you pay $12.50 of GST and then $17.50 of provincial tax on top, which is $30.00 of tax and $280.00 at the till, and that’s why a single rate never tells the whole story.
Quebec works out a little differently. On $1,000 the GST is $50.00 and the QST is $99.75, and the QST is worked out on the price before tax, not on the price plus GST. The total is $1,149.75. You can check your own numbers with the GST and QST calculator.
For a purchase in British Columbia, Saskatchewan or Manitoba, use the GST and PST calculator. It applies both taxes to the price before tax.
Where do GST amount calculations go wrong?
Rounding is the first trap. The CRA says its own calculator results can be a cent or two off a final total, and that’s normal. Businesses that invoice many lines sometimes round each line, sometimes the total, and the two can differ by a few cents.
Then there are items that carry no tax at all, and they catch out even careful bookkeepers who assume every line on an invoice is taxable. Some goods and services are zero-rated or exempt, and the calculators can’t know which yours are. The GST/PST tool also applies both taxes to everything, and some items, like certain food or children’s goods, are exempt from one tax but not the other. If a receipt shows less tax than the tool does, the receipt is probably right.
A third mistake is using the wrong rate for the location of the sale. Where a service or product is supplied can differ from where you live, and we haven’t covered those rules here. Check the CRA’s guidance before you charge a customer in another province.
Small suppliers don’t always have to charge GST. If you sell as a business, look up the current small supplier limit on the CRA site before you register or skip registration. We haven’t confirmed that figure for this page, so we’re not quoting it.
What should a business put on an invoice?
Show the price, then the GST or HST as its own line, then the total. If you’re registered, your GST/HST number goes on it as well. Customers who claim input tax credits need to see the amount of tax, and it’s easier to give it than to answer questions about it later.
Buying a new home is a special case. The tax can be large and there are rebates, which the new housing rebate calculator estimates.
Where do the numbers come from?
The rates come from the Canada Revenue Agency’s GST/HST rates by province page, and the tax-included fraction from its guidance on calculating tax. We checked them on September 30, 2026. Manitoba’s 7% rate comes from the province’s own retail sales tax page. This website has no connection with the CRA or any government.
Frequently asked questions
How do I find the GST amount on a total that already includes tax?
Multiply the total by 5/105 if the tax is 5% GST. A $105 receipt holds $5.00 of GST.
Is GST always 5%?
Yes, the federal rate is 5%. In HST provinces the federal and provincial parts are combined at 13%, 14% or 15%.
Is the QST charged on top of the GST?
In our calculator both are worked out on the price before tax. On $1,000 that is $50.00 GST and $99.75 QST.
Why does my receipt differ from the calculator by a cent?
The CRA says results can differ by a cent or two because of rounding. Stores round in different places.
Do I have to charge GST if I run a small business?
Not always. Small suppliers below the CRA limit can skip it, but we haven't confirmed the current limit, so check the CRA page.
- GST, HST, PST and QST explained for every province
Which GST, HST, PST or QST applies where you shop or sell in Canada, the 2026 rates for every province, who must register and how to add or remove tax
Information only. This page is general information, not tax, legal or accounting advice. Tax-Services.ca is an independent publisher: we don't prepare or file tax returns or offer tax services, and we have no connection with the CRA, Revenu Québec, any government or any company named on this page. Check the figures that matter with an official source or a qualified professional.