GST Calculator
Add GST to a price or take it out of a GST-inclusive total. Enter any rate, or tap a preset for Australia, New Zealand, Singapore, Canada or India.
How to Use
- Pick a mode: choose Add GST if your amount is before GST, or Remove GST if the amount already includes GST.
- Enter the amount: any currency works, and the results use the same one. Negative amounts are fine for refunds and credit notes.
- Set the GST rate: type any rate, or tap a preset to fill it in. Typing your own rate clears the preset highlight.
- Read the results: the price before GST, the GST amount and the price including GST update as you type.
What You'll Discover
- Total including GST (Add GST mode): the price your customer pays once GST is added to your GST-exclusive price.
- Price before GST (Remove GST mode): the GST-exclusive price hidden inside a tax-inclusive total.
- GST amount: the tax portion in dollars, rupees or any other currency, rounded to the cent.
- Figures that add up: the calculator rounds the GST amount once and works the other figures from it, so the price before GST plus GST always equals the price including GST on screen.
The calculator applies one rate to one amount and shows the total GST only. It does not split GST into CGST, SGST or IGST. If a rate is blank or negative, or an amount is blank, the results show a dash.
GST Formulas: Adding and Removing GST
GST is a percentage of the price, so the maths is simple once you know which price you start with. To add GST to a GST-exclusive price, multiply by 1 plus the rate. To remove GST from a GST-inclusive price, divide by the same number.
Add: GST = price × rate ÷ 100 | Total = price + GST
Remove: GST = total × rate ÷ (100 + rate) | Price = total − GST
The second formula is the one people get wrong. GST is a percentage of the price before tax, so on an inclusive total it is a smaller share than the headline rate. At 10% the GST is one-eleventh of the total, not one-tenth. The table shows the share for rates this calculator offers.
| Rate | Multiply the price by | GST as a share of the total | $1,000 before GST becomes |
|---|---|---|---|
| 5% | 1.05 | 5 ÷ 105 ≈ 4.76% | $1,050 |
| 9% | 1.09 | 9 ÷ 109 ≈ 8.26% | $1,090 |
| 10% | 1.10 | 1 ÷ 11 ≈ 9.09% | $1,100 |
| 13% | 1.13 | 13 ÷ 113 ≈ 11.50% | $1,130 |
| 15% | 1.15 | 3 ÷ 23 ≈ 13.04% | $1,150 |
| 18% | 1.18 | 9 ÷ 59 ≈ 15.25% | $1,180 |
For example, $330 including 10% GST contains $330 ÷ 11 = $30 of GST, so the price before GST is $300. If you only know the GST amount, divide it by the rate: $45 of GST at 15% means a price of $45 ÷ 0.15 = $300 before GST.
GST Rates by Country and Where the Presets Come From
Each preset is a rate published by the country's tax authority. The table lists the source for every one, so you can check it yourself. Rates change, and the right rate for a particular item or supply can differ from the standard rate, so confirm it with the authority before you invoice. This page is for calculation and is not tax advice.
| Country | Rate used in the presets | Official source |
|---|---|---|
| Australia | 10% on most goods, services and other items sold or consumed in Australia | business.gov.au |
| New Zealand | 15% | Inland Revenue (ird.govt.nz) |
| Singapore | 9% | IRAS (iras.gov.sg) |
| Canada | 5% federal GST; HST of 13% in Ontario, 14% in Nova Scotia and 15% in other participating provinces | Canada Revenue Agency |
| India | 5% merit rate, 18% standard rate and a 40% special rate for a select few goods and services, from 22 September 2025 | Press Information Bureau |
India's rate structure
The GST Council's 2025 reform replaced the earlier four-tier structure with a two-rate system, a standard rate of 18% and a merit rate of 5%, plus a special rate of 40% for a select few goods and services. The changes took effect on 22 September 2025, with tobacco products handled separately. Which rate applies to a product or service depends on how it is classified, so check the official rate schedules on cbic-gst.gov.in for your item.
Why there is no Malaysia preset
Malaysia is not a GST country any more. It charges sales tax and service tax (SST), administered by the Royal Malaysian Customs Department, with rates that depend on the type of goods or service. See mysst.customs.gov.my for current rates. You can still enter any SST rate in the rate box to get the same add and remove maths.
Registration, Rounding and Common GST Mistakes
Whether you must charge GST at all depends on your turnover. In Australia, a business must register when its GST turnover is $75,000 or more, and a non-profit organisation when its GST turnover is $150,000 or more (business.gov.au). In New Zealand you must register if you carry out a taxable activity and your turnover was at least $60,000 in the last 12 months, or you expect it to be at least $60,000 in the next 12 months (Inland Revenue). Other countries set their own thresholds.
Once you charge GST, most errors come from using the wrong starting price or the wrong operation. The table lists the usual ones, each worked with the 10% rate.
| Mistake | What goes wrong | Correct approach |
|---|---|---|
| Subtracting the rate from a GST-inclusive price | $110 less 10% is $99, but the real price before GST is $100 | Divide $110 by 1.10 to get $100, or take GST as $110 ÷ 11 = $10 |
| Taking one-tenth of an inclusive price as the GST | $110 ÷ 10 = $11, which overstates the GST by $1 | At 10% the GST in an inclusive price is one-eleventh, so $10 |
| Adding GST to a price that already includes it | $110 × 1.10 = $121, so GST is charged twice | Use Remove GST first, or only add GST to a price before GST |
| Rounding each line, then comparing with the total | Lines of $24.99, $13.50 and $9.95 at 10% carry GST of $2.50 + $1.35 + $1.00 = $4.85, but GST on the $48.44 total is $4.84 | Pick one method for the whole invoice and stick to it; the rule that applies to you depends on your tax authority and accounting software |
This calculator rounds the GST amount to the nearest cent, with halves rounded away from zero, and works the other figures from it. If your invoicing rules call for GST on each line, enter the lines one at a time and add up the results.
How Much Is GST If...
How much is GST if a price is $100 before GST at 10%?
The GST is $10 and the total is $110. Multiply $100 by 10 ÷ 100 to get $10, then add it to the price. This is the standard Australian case, and you can confirm it by choosing the Australia preset.
How much GST is in $50 if the price includes 10% GST?
The GST is $4.55 and the price before GST is $45.45. Use $50 × 10 ÷ 110 = $4.545, which rounds to $4.55, then subtract it: $50 − $4.55 = $45.45. Taking 10% of $50 would give $5.00, which is wrong because the $50 already contains the tax.
What is the GST if a New Zealand price is $230 including 15% GST?
The GST is $30 and the price before GST is $200. At 15% the GST is 15 ÷ 115, or three twenty-thirds, of the total: $230 × 15 ÷ 115 = $30. Check it by adding 15% to $200, which gives $230.
What is the total if a Singapore item costs $1,000 before 9% GST?
The GST is $90 and the total is $1,090. Multiply $1,000 by 0.09 for the tax, then add it. Going the other way, the same $1,090 divided by 1.09 returns $1,000.
How much GST is in a Singapore price of $545 including 9% GST?
The GST is $45 and the price before GST is $500. Compute $545 × 9 ÷ 109 = $45, then $545 − $45 = $500. Switch the calculator to Remove GST and choose the Singapore preset to see the same figures.
What is the GST if a price is ₹5,000 before 18% GST?
The GST is ₹900 and the total is ₹5,900. ₹5,000 × 18 ÷ 100 = ₹900. The calculator shows the total GST only and does not split it into CGST, SGST or IGST.
How much is GST if a price is ₹2,000 before 5% GST?
The GST is ₹100 and the total is ₹2,100. Multiply ₹2,000 by 5 ÷ 100 for ₹100. Use the India 5% preset for the merit rate.
How much HST is added to $200 in Ontario?
At the 13% Ontario HST rate, $200 attracts $26 of HST for a total of $226. By comparison, the 5% federal GST alone would add $10, for $210. Which of these applies depends on where the supply is made, so check the Canada Revenue Agency's place-of-supply rules.
What is the GST if I am entering a refund or credit note?
A negative amount gives a negative GST amount. Entering −110 in Remove GST mode at 10% returns a price before GST of −100 and GST of −10, so the credit note mirrors the original invoice.
What is the GST if a price is $19.99 including 10% GST?
The GST is $1.82 and the price before GST is $18.17. The exact GST is $19.99 × 10 ÷ 110 = $1.8173, which rounds to $1.82. The calculator then works the price before GST as $19.99 − $1.82 = $18.17, so the figures add back to $19.99.
People Also Search For
How to calculate GST on a price
Multiply the price by the GST rate and divide by 100, then add the result to the price. For $250 at 10%: $250 × 10 ÷ 100 = $25, so the total is $275. In one step, multiply by 1.10.
How to calculate GST from a GST-inclusive price
Multiply the total by the rate and divide by 100 plus the rate. For $330 including 10% GST that is $330 × 10 ÷ 110 = $30, leaving $300 before GST. In Australia this is the same as dividing by 11, because GST is one-eleventh of the sale price.
How to find the original price from the GST amount
Divide the GST amount by the rate written as a decimal. If the invoice shows $18 of GST at 18%, the price before GST is $18 ÷ 0.18 = $100. If it shows $45 at 15%, the price before GST is $45 ÷ 0.15 = $300.
GST vs VAT
The arithmetic is identical: a percentage is added to a price or divided out of an inclusive total. Rules and rates differ by country, but if you only need the maths, our VAT calculator works the same way as this one.
How to calculate GST in Excel or Google Sheets
Put the price in A1 and the rate in B1 as a percentage, then use a formula for each result. To add GST use =A1*(1+B1). To remove GST use =A1/(1+B1). To find the GST inside an inclusive price use =A1*B1/(1+B1). Wrap a formula in ROUND(..., 2) to match a rounded invoice.
How to add GST to a discounted price
Apply the discount first, then add GST to the reduced price. A $200 item with 20% off costs $160, the 10% GST is $16 and the total is $176. Use the discount calculator for the sale price, then enter it here. Rules for vouchers and coupons vary, so confirm the treatment with your tax authority.
Frequently Asked Questions
What is GST?
GST stands for Goods and Services Tax, a tax charged as a percentage of the price of goods and services. It is used in countries including Australia, New Zealand, Singapore, Canada and India. The rate and the rules differ by country, so check your tax authority for the rate that applies to you.
How do I add GST to a price?
Multiply the price before GST by 1 plus the rate as a decimal. At 10%, multiply by 1.10, so $100 becomes $110. The GST is the difference, $10. In the calculator, choose Add GST, enter the price and the rate.
How do I remove GST from a GST-inclusive price?
Divide the total by 1 plus the rate as a decimal. At 10%, $110 divided by 1.10 is $100, so the GST is $10. An equivalent shortcut is total × rate ÷ (100 + rate) for the GST amount. Choose Remove GST in the calculator to do this for you.
Why can't I just subtract 10% to remove 10% GST?
Because the 10% was calculated on the price before GST, not on the total. Taking 10% off $110 leaves $99, but the original price was $100. To undo the tax correctly, divide by 1.10, or take one-eleventh of the total as GST.
What is the GST rate in Australia?
Australian GST is 10% on most goods, services and other items sold or consumed in Australia, according to business.gov.au. That makes the GST in a GST-inclusive price one-eleventh of that price. Some supplies are treated differently, so check the Australian Taxation Office for your item.
What are the current GST rates in India?
Since 22 September 2025 the structure has a standard rate of 18% and a merit rate of 5%, plus a special rate of 40% for a select few goods and services, as set out in the Press Information Bureau release on the 56th GST Council meeting. The rate that applies to an item depends on its classification, so check the official schedules.
Does this calculator split GST into CGST, SGST and IGST?
No. It shows the total GST amount only. If your invoice needs a breakdown into central, state or integrated components, take the total from this calculator and follow the guidance on cbic-gst.gov.in.
Why is there no Malaysia preset?
Malaysia now charges sales tax and service tax (SST) rather than GST, and its rates depend on the type of goods or service. You can type an SST rate into the rate box and the add and remove maths works the same way. Check mysst.customs.gov.my for current rates.
Can I use this for Canadian GST and HST?
Yes, for a single combined rate. The Canada Revenue Agency lists 5% federal GST and HST of 13% in Ontario, 14% in Nova Scotia and 15% in other participating provinces. Enter the rate for where the supply is made. If you also pay a separate provincial tax, calculate each tax on its own, because the calculator applies one rate at a time.
How does the calculator round?
It rounds the GST amount to the nearest cent, with exact halves rounded away from zero, and works the other figures from it. That way the price before GST plus the GST always equals the price including GST on screen, with no stray cent.
Can I enter a negative amount for a refund?
Yes. A negative amount produces negative GST and a negative price, which suits refunds and credit notes. The rate itself cannot be negative.
Do I need to register for GST?
It depends on your country and turnover. In Australia the threshold is a GST turnover of $75,000 for a business and $150,000 for a non-profit organisation. In New Zealand it is turnover of at least $60,000 in the last 12 months, or expected in the next 12 months. Confirm your own position with your tax authority.
Is this tax advice?
No. The calculator does arithmetic with the rate you give it. Rates, exemptions and rounding rules change and vary by country and by product, so confirm what applies to you with your tax authority or a qualified adviser before you file or invoice.
Is my data stored or sent anywhere?
No. All calculations run in your browser. Nothing you type is sent to a server or saved, and no account is needed.
Last reviewed: November 2026 — formulas and worked examples verified.