Reverse HST Calculator (Ontario & All Provinces)
Pull the HST back out of a receipt total — Ontario's 13%, or any province's rate — or add tax to a before-tax price.
The short answer
Formula. HST inside a total = total × rate ÷ (100 + rate); the before-tax price = total ÷ (1 + rate as a decimal).
Example. An Ontario receipt totalling $113.00 contains exactly $13.00 of HST (13%) and $100.00 of goods.
The tax-included total on your receipt.
Rates verified against the CRA's published GST/HST rates, October 2026. NS dropped from 15% to 14% on April 1, 2025. PST provinces: the combined option applies to goods that carry both taxes.
How the math works
Every receipt total is really two numbers wearing one price tag: the price of the thing, plus tax on that price. If the rate is r, then total = price × (1 + r), so pulling the tax out is division, not subtraction: price = total ÷ (1 + r), and the tax is total − price. In Ontario (13%), a $113.00 total is $113 ÷ 1.13 = $100.00 of goods and $13.00 of HST. The tempting shortcut — "13% of $113" — gives $14.69, which is wrong by the tax-on-tax amount, and exactly the kind of penny-off that makes expense reports and bookkeeping reconciliation fail.
Working the small percentages by hand gets fiddly, so here are the reverse factors worth memorizing: divide by 1.13 for Ontario, 1.14 for Nova Scotia (since April 2025), 1.15 for the three 15%-HST Atlantic provinces, and 1.05 for the 5% GST-only provinces and territories. Quebec's stacked GST + QST lands at 14.975% combined, so its divisor is 1.14975. The "add" mode simply runs the same equation forward for pricing from a before-tax cost.
Two real-world wrinkles. In BC, Saskatchewan and Manitoba, the provincial sales tax is separate from the GST — it applies to most goods but a different basket of services, and some items (basic groceries, prescription drugs, children's clothing in various provinces) are zero-rated or exempt entirely; the combined presets here suit a typical goods receipt, and the custom rate covers anything unusual. And for business use — recovering input tax credits or reconciling invoices in accounting software — the removed-tax number is the HST/GST actually collectible on that sale; keep the calculator's rounding to the cent, because CRA reconciliations do.
Sources & review date
- All Canadian rates verified against the CRA's published GST/HST rate table, October 2026.
- Nova Scotia dropped from 15% to 14% effective April 1, 2025 — receipts before that date use 15%.
Last reviewed: October 2026. Numbers that drift (fees, prices, densities) are editable inputs on this page.
Reverse HST FAQs
How much HST is in a $200 total in Ontario?
$200 ÷ 1.13 = $176.99 before tax; the HST is $23.01. The calculator keeps it to the cent — the answer is $23.005 before rounding, which matters in bookkeeping.
Do I back out HST on groceries?
Basic groceries are zero-rated — no HST inside that part of the bill, so back-calculating it out would fabricate a credit. Only reverse tax on portions of a receipt that actually carry it (prepared food, snacks, non-food items do).
Is Quebec's QST calculated the same way?
QST is charged on the price without GST, but the combined effect on the bill is 5% + 9.975% ≈ 14.975%. Divide a tax-inclusive Quebec total by 1.14975 to remove both; the preset does exactly that.
Which rate applies to online purchases?
Generally the destination province's rate — the tax inside an online order shipped to Ontario is 13% HST regardless of where the seller sits. Cross-border orders add duty and GST/import handling on the courier's brokerage bill, a different math altogether.