GST Calculator
Estimate GST totals, payments, rates, and costs for financial planning.
This GST calculator adds Goods and Services Tax to a price (before GST) or removes it from a GST-inclusive price (with GST) to reveal the amount without GST, at any percentage rate. It works the same way for any country that uses a GST system, such as Australia, Canada, India, or New Zealand, provided you use the correct local rate.
Enter a price and GST rate, choose add or remove, and the calculator returns both the GST amount and the net/gross totals.
Worked Calculation Examples
| Scenario | Result | Calculation Step |
|---|---|---|
| Adding 10% GST to a $100 exclusive price | $110.00 gross ($10.00 GST) | Gross = $100 × 1.10 = $110.00. GST amount = $110.00 − $100.00 = $10.00. |
| Removing 10% GST from a $220 inclusive price | $200.00 net ($20.00 GST) | Net = $220 ÷ 1.10 = $200.00. GST amount = $220.00 − $200.00 = $20.00 - simply subtracting 10% of $220 would incorrectly give $22.00. |
Adding GST to a Price
To add GST, multiply the GST-exclusive price by (1 + GST rate as a decimal). At a 10% GST rate, a $100 exclusive price becomes $110 inclusive - the $10 difference is the GST amount charged.
Removing GST from a Total
To back out GST from a GST-inclusive price, divide by (1 + GST rate) rather than simply subtracting the percentage - a $110 inclusive price at 10% GST has a $100 exclusive price ($110 / 1.10), not $99.
How to Use the GST Calculator
- Open the GST Calculator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the gst calculator works.
Frequently Asked Questions
How do I calculate GST on a price?
Multiply the GST-exclusive price by the GST rate (as a decimal) to find the GST amount, then add it to get the GST-inclusive total.
How do I remove GST from a total price?
Divide the GST-inclusive price by (1 + GST rate) to find the exclusive price - simply subtracting the percentage from the total gives an incorrect result.
What GST rate should I use?
GST rates vary by country - for example, 10% in Australia or 5% federally in Canada (plus provincial tax in most provinces) - so use the specific rate that applies to your country and goods or services.
How do I use this gst calculator?
Enter the known values, review the units or settings, and the calculator updates the result instantly. The formula and example on this page show how the answer is produced.
What does the GST Calculator calculate?
Estimate GST totals, payments, rates, and costs for financial planning. It is designed for fast browser-based calculations without sign-up, downloads, or manual spreadsheet setup.
What formula does this gst use?
The formula is: Gross Price = Net Price × (1 + GST Rate). GST operates on the same value-added tax principle as VAT, just under a different name adopted by countries including Australia, Canada, India, and New Zealand. New Zealand's 1986 GST system, in particular, became an influential model for other countries because it was designed with a broad base and very few exemptions, which tax economists generally consider more efficient than systems riddled with special-case carve-outs, even though it means GST typically applies to a wider range of goods and services than many older sales tax systems.
Related Calculators
Property Tax Calculator
Estimate Property Tax totals, payments, rates, and costs for financial planning.
VAT Calculator
Add or remove VAT from a price at any standard VAT rate.
HSA Contribution Calculator
Estimate HSA Contribution totals, payments, rates, and costs for financial planning.
Student Loan Calculator
Calculate monthly student loan payments and total interest cost.
Loan Calculator
Calculate monthly loan payments, interest charges, and loan payoff terms.
Mortgage Calculator
Estimate home mortgage payments including principal, interest, taxes, and insurance.
Last updated: September 27, 2026.