Ontario HST Reverse Calculator
Calculate the estimated pre-tax price and included HST for Ontario, Canada tax-inclusive totals. Use this when you need to remove HST from a total or check a receipt where 13% HST is already baked into the price.
Calculator
Calculate tax backwards
$247.80 at 13% Ontario HST: pre-tax $219.29, Ontario HST $28.51.
Estimate only. Verify official rates before filing, invoicing, or making tax decisions.
Calculator
Ontario HST Reverse Calculator
Starting rate
13%
Rate source
Ontario Harmonized Sales Tax (HST) overviewLast updated
2026-05-15
Formula
How reverse tax calculation works
Start with the tax-inclusive total, then divide by 1 plus the tax rate. Use the tax rate as a decimal in the formula.
Pre-tax Price = Total Price / (1 + Tax Rate)
Tax Amount = Total Price - Pre-tax Price
Example
$247.80 CAD with 13% HST
- Tax multiplier = 1.13
- Pre-tax price = 247.80 / 1.13 = 219.29
- Estimated HST amount = 28.51
Region
Ontario tax context
Country
Canada
Tax system
HST
Rate shown
13%
Ontario uses harmonized sales tax for many goods and services. Always verify the rate for the exact product, location, and filing period before making tax decisions.
Rate breakdown
Estimated split for $247.80.
- Federal part5% rate shown
- 5% / $10.96
- Ontario provincial part8% rate shown
- 8% / $17.54
Source checked 2026-05-15: Ontario Harmonized Sales Tax (HST) overview. Ontario HST is 13%, consisting of a 5% federal part and an 8% provincial part.
FAQ
Common questions
How do you reverse calculate tax?
Divide the tax-inclusive total by 1 plus the tax rate. For example, with a 20% tax rate, divide the total by 1.20.
What is the reverse tax formula?
Pre-tax price = total price / (1 + tax rate). Tax amount = total price - pre-tax price.
Is this calculator tax advice?
No. This is an educational calculator for estimates. Confirm official rates and rules before filing, invoicing, or relying on the result.
What Ontario HST rate does this page use?
This page starts with 13% as the Ontario HST rate for estimates.
Is Ontario HST calculated differently from GST plus QST?
The reverse formula is the same, but Ontario uses one harmonized 13% HST rate. Quebec commonly combines separate GST and QST components.
How do I remove 13% HST from an Ontario total?
Divide the HST-inclusive total by 1.13. Then subtract the net price from the total to estimate the included HST amount.
How do I calculate HST backwards from a total?
Convert 13% to 0.13, add one to get 1.13, and divide your tax-inclusive total by that multiplier. The result is the pre-tax base; subtract it from the total to see the HST portion.
How do I get the pre-tax price from an HST-inclusive receipt?
Use the same division: pre-tax equals total divided by 1.13 when the whole line is subject to the standard Ontario HST rate. If some lines are zero-rated or exempt, split the receipt before applying one rate to everything.
Is backing out HST the same as subtracting 13% from the total?
No. Thirteen percent was applied to the pre-tax amount, not to the final total. Dividing by 1.13 reverses that correctly; subtracting 13% of the gross total usually understates the pre-tax base.
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