Reverse HST Calculator
Last updated: October 18, 2026
Use this free HST calculator to calculate the Harmonized Sales Tax or perform a reverse HST calculation.
Enter an amount in any one of these fields:
- Price before HST—to calculate the HST and total price.
- HST amount—to calculate the prices before and after HST.
- Price including HST—to calculate the included HST and price before tax.
The remaining fields update automatically.
How the reverse calculation works
Price before HST = Price including HST ÷ (1 + HST rate). For example, at 13% HST, $113.00 ÷ 1.13 = $100.00, so the HST included is $13.00.
Want to add HST to a price instead? Use the HST Calculator.
Tired of adding up HST by hand? HST Helper scans your invoices and records the HST for you.
/made-in-canada-4225/images/button-made-in-canada-red-outline-2.png){kind=small}