Reverse sales tax calculator
Know the total and need the price before tax? Back the tax out of any amount, for any province.
Calculation mode
- Subtotal
- $88.50
- HST 13%
- $11.50
- Total
Get it on your phone
The same calculator, offline, with every province built in.
How it’s calculated
Adding tax to $100.00
Total = price × (1 + combined rate)
- Subtotal
- $100.00
- HST 13%
- $13.00
- Total
- $113.00
Removing tax from $100.00
Price = total ÷ (1 + combined rate)
- Subtotal
- $88.50
- HST 13%
- $11.50
- Total
- $100.00
Examples use Ontario at 13%. Change the province above to see another.
Working backwards from a total
You have the total. You need to know what it was before tax, and how much tax is inside it. That comes up constantly in expense and invoicing work: a receipt shows one tax-included figure, your books need the subtotal and the tax separately.
The formula
Divide the total by 1 plus the combined rate. The result is the price before tax, and whatever’s left over is the tax.
The mistake to avoid
Subtracting the tax percentage from the total is not the same calculation and gives the wrong answer. The tax was calculated on the pre-tax price, which is smaller than the total, so taking that percentage off the larger number removes too much. The gap is small on a coffee and material on a $50,000 contract.
Two taxes at once
In provinces that charge GST plus a provincial tax, back the total down to the pre-tax price first, then calculate each tax on that figure. Because the two taxes apply to the same base rather than one stacking on the other, this splits cleanly into two lines.
Pick a province above, or browse every province and territory.
Common questions
How do I calculate sales tax backwards?
Divide the total by 1 plus the combined tax rate. In a 13% province, divide by 1.13. The result is the price before tax, and the difference is the tax.
Why can't I just subtract 13% from the total?
Because the tax was calculated on the smaller pre-tax price, not on the total. Subtracting 13% from the total takes off too much. On a $113 total the tax is $13, not $14.69.
How do I split a Quebec total into GST and QST?
Divide the total by the combined rate to get the price before tax, then calculate each tax on that figure. Both apply to the same base, so neither is compounded.
Is reverse calculation free in Tax Moose?
Yes, on the web and in the app. It isn't behind a purchase.
What is reverse calculation used for?
Reconciling tax-included receipts, splitting an expense between accounts, checking a supplier's invoice, and pricing a job so the client's total comes out to a round number.