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GST calculator Singapore

Add GST to a price, or work out how much GST is inside a GST-inclusive amount. Enter one figure or a whole list of line items, then copy the result.

In short: At the current 9% rate, $100 before GST becomes $109, and the GST inside an inclusive price is 9/109 of it, so $7.43 on $90. GST-registered businesses must quote GST-inclusive prices, and registration is required once taxable turnover is more than S$1 million.

What do you want to do?
Line items
Amount before GST-
GST at 9%-
Amount with GST-

Rate checked October 2026 on the IRAS website. Each line is rounded to the cent, so totals are the sum of rounded lines. Results are estimates, not tax advice.

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How the calculator works

To add GST, the calculator multiplies the price before GST by the rate. At 9%, a $100 price carries $9 of GST and becomes $109.

To extract GST from a GST-inclusive price, it multiplies the inclusive price by the tax fraction, which is the rate divided by 100 plus the rate. At 9% that fraction is 9/109, the same fraction IRAS uses in its own price display example. On $109 the GST is $9, and on $90 it is $7.43.

Batch mode works the same way for every line. Add a line for each item on a quote or invoice, give it a description if you like, and the calculator shows the GST for each line and the totals. "Copy result" copies a tab-separated table that pastes straight into Excel or Google Sheets.

The calculator rounds each line to the nearest cent and adds the rounded lines together. Your accounting software may round GST on the invoice total instead, which can move the total by a cent or two.

When a business must register for GST

IRAS sets the registration threshold at taxable turnover of more than S$1 million, tested in two ways:

  • Retrospective basis. Your taxable turnover was more than S$1 million at the end of a calendar year (1 January to 31 December). IRAS says you must apply between 1 and 30 January of the following year.
  • Prospective basis. You can reasonably expect taxable turnover of more than S$1 million in the next 12 months, for example because of a signed contract. IRAS says you must apply within 30 days of making that forecast.

Registration has knock-on work: once registered you charge GST on your taxable supplies and file GST returns, usually every quarter. IRAS's page sets out when registration takes effect for each basis and what counts as taxable turnover, so check it before you decide.

Price display rules for GST-registered businesses

IRAS says a GST-registered business must display and quote prices inclusive of GST to the public. The rule covers price tags and price lists, advertisements and brochures, prices on websites, and written or verbal quotes. Not displaying GST-inclusive prices may result in a fine of up to $5,000.

  • You may show the GST-exclusive price as well, but the GST-inclusive price must be at least as prominent.
  • Where prices are bargained, the displayed price must still include GST, and the GST you account for is worked out on the final agreed price using the 9/109 fraction.
  • Hotels and F&B outlets that impose a service charge may show prices before GST if they display a prominent statement that prices are subject to GST and service charge. The exception does not apply to outlets that do not impose a service charge.

The extract mode in the calculator is useful here: if you set a round GST-inclusive shelf price, it tells you how much of it is GST and how much is your revenue.

What changes the numbers

  • The rate. IRAS lists 8% for 1 January to 31 December 2023; the current rate is 9%. Use the rate that applied when the supply was made if you are checking an older invoice.
  • Rounding. Rounding per line and rounding on the total can differ by a cent or two on long invoices.
  • Whether GST applies at all. Not every supply is standard-rated. If you are unsure how GST treats a particular sale, check with IRAS or an accountant before quoting.

Sources

Getting help with GST

If you are close to the S$1 million threshold, or already registered and filing quarterly returns, an accountant can handle registration, GST returns and the bookkeeping behind them. Compare accounting and bookkeeping firms or read our guide to the best accounting firms in Singapore.

Frequently asked questions

What is the GST rate in Singapore?

IRAS states that the current GST rate in Singapore is 9%. It was 8% from 1 January 2023 to 31 December 2023. The calculator uses 9% by default, and you can change the rate if you are checking an older invoice.

How do I work out the GST inside a GST-inclusive price?

Multiply the GST-inclusive price by the tax fraction 9/109. IRAS uses this fraction in its own example: GST on a final price of $90 is 9/109 x $90 = $7.43. Choose "Extract GST from a GST-inclusive price" in the calculator to do this for one amount or many.

When must a business register for GST?

IRAS requires registration when taxable turnover was more than S$1 million in a calendar year (the retrospective basis), or when you expect it to be more than S$1 million in the next 12 months (the prospective basis). Check the IRAS page for the deadlines that apply to each basis.

Do GST-registered businesses have to show prices with GST?

Yes. IRAS says GST-registered businesses must display and quote prices to the public inclusive of GST, on price tags, advertisements, websites and quotes. Not doing so may result in a fine of up to $5,000. Hotels and F&B outlets that impose a service charge have a limited exception.

Is anything I type sent anywhere?

No. The calculation runs in your browser. Nothing is sent to FYAdvisers unless you choose to request quotes using the form below the calculator.