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To calculate GST from a total, divide the total by one plus the tax rate, then subtract to see the tax. A $1,130 bill in Ontario holds $1,000 of price and $130 of HST, because 1,130 divided by 1.13 is 1,000.
Why do you divide instead of taking a percentage?
Sales tax gets added on top of the price. At 13%, the total is 113% of the price. Going backward, you divide by 1.13 to find the price, and the tax is whatever is left over.
Plenty of people take 13% of the total instead. You’ll get $146.90 on $1,130, which is wrong by almost $17. The 13% belongs to the price before tax, not to a total that already has the tax baked in.
The HST reverse calculator does the division for any province. Want to go the other way, from a price to a total? You’ll want the GST/HST calculator.
What are the steps, start to finish?
Three of them. First, find the combined rate for the place of sale. Second, divide the total on the receipt by one plus that rate, which gives the price before tax. Third, subtract that price from the total, and what’s left is the tax.
Say Jordan in Ottawa has a $275.00 receipt for office supplies. Divide by 1.13 and the price is $243.36, so the HST is $31.64. Add them back and you land on $275.00. That last add-back is the quick way to check your work. For a rough ballpark in your head, 13% HST is a little over 11% of an Ontario total. In Alberta the same idea with only 5% GST turns a $52.50 total into $50.00 plus $2.50.
Which rate do you divide by in each province?
Use the rate for the place where the sale is made, not where you live. The CRA’s page on which GST/HST rate to charge says the rate depends on the province or territory, and confirms 14% HST in Nova Scotia. These are the combined rates the calculators use for 2026.
| Province or territory | Tax | Rate to use |
|---|---|---|
| Ontario | HST | 13% |
| Nova Scotia | HST | 14% |
| New Brunswick, Newfoundland and Labrador, Prince Edward Island | HST | 15% |
| Alberta, Yukon, Northwest Territories, Nunavut | GST only | 5% |
| British Columbia | GST plus PST | 5% + 7% = 12% |
| Saskatchewan | GST plus PST | 5% + 6% = 11% |
| Manitoba | GST plus RST | 5% + 7% = 12% |
| Quebec | GST plus QST | 5% + 9.975% = 14.975% |
How much tax is in $1,130 in six places?
Here’s the same $1,130.00 receipt total, run through the reverse calculator for six provinces. You’ll see it isn’t a small difference.
| Place | Price before tax | Tax inside |
|---|---|---|
| Ontario | $1,000.00 | $130.00 |
| Alberta | $1,076.19 | $53.81 |
| British Columbia | $1,008.93 | $121.08 |
| Nova Scotia | $991.23 | $138.77 |
| Quebec | $982.82 | $147.18 |
| Saskatchewan | $1,018.02 | $111.98 |
In British Columbia the $121.08 splits into $50.45 of GST and $70.63 of PST. In Quebec it’s $49.14 of GST and $98.04 of QST. Both are worked out on the price before tax. So you divide by the combined rate once, not by each rate in turn.
What if you only need the GST part?
Sometimes you’ll need just the federal 5% from a receipt, say for a business claiming input tax credits in a province with a separate PST. If the receipt holds GST alone, you divide the total by 1.05. If PST is charged too, you use the combined rate first and then take the GST share. In the British Columbia line above, that share comes to $50.45.
For provinces with their own tax, the GST and PST calculator and the GST and QST calculator show each part on a price before tax.
Where do people go wrong?
- They multiply the total by the rate instead of dividing by one plus the rate.
- They use their home province’s rate, when the rate follows where the sale is made.
- They add tax to items that carry none. Basic groceries and some other items are zero-rated or exempt, so the receipt may show no tax at all.
- They expect the cents to match. Stores round each line, so you’ll land one cent off the receipt.
- They trust an old source. Nova Scotia HST changed to 14% on 1 April 2025, and older articles still show 15%.
Running a business and need the amounts for a return? Keep the original receipt and use the tax figure printed on it, because your own percentage is only a check and won’t stand in for it.
Our sources
Rates come from the Canada Revenue Agency table of GST/HST and provincial rates and from provincial tax pages, checked on 29 September 2026. Manitoba’s RST at 7% and the Quebec QST at 9.975% match the provinces’ own pages, but rates change, so confirm them on the receipt before you rely on them for a filing. The new housing rebate calculator covers tax on a home purchase, which follows other rules.
Frequently asked questions
How do I find the GST in a total that includes tax?
Divide the total by 1.05 for GST alone, then subtract the result from the total. What's left is the GST.
Why not take 13% of the total in Ontario?
Because the 13% applies to the price before tax. Taking it from the total overstates the tax: $146.90 instead of $130 on $1,130.
How much tax is in $1,130 in Alberta?
Alberta charges GST only, at 5%. The price is $1,076.19 and the tax is $53.81.
Which rate do I use for a sale in British Columbia?
GST is 5% and PST is 7%. Divide by 1.12 for the combined amount, which gives $50.45 GST and $70.63 PST on $1,130.
Why is my answer one cent off the receipt?
Stores round each line and may round tax per item, so a one cent gap is normal.
- 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