GST Calculator - Add or Remove GST, CGST, SGST, IGST

Tax added to a price

Add GST mode

Taxable value

the value the tax is charged on

Tax

GST: CGST and SGST together, or IGST, in India; HST, or GST with the provincial tax, in Canada

Total

the price including tax

Rate

the whole rate, every tax on the price together, in percent

Each tax is worked on its own and rounded to the cent (the paisa in India) before they are added. In India within a state, CGST and SGST are each Taxable value × (Rate ÷ 2) ÷ 100; between states, IGST is the whole tax. In Canada, GST and the province’s PST, RST or QST are each the taxable value × its own rate, never one on the other; HST is one tax. A blank discount counts as zero.

Source: India: the central tax rate is half of each GST rate in Notification 9/2025-Central Tax (Rate) [2], in force from 22 September 2025 [1]; a supply between states is inter-State and carries IGST (IGST Act, sections 7 and 8) [3]. Canada: GST on the price without the PST [11], QST on the selling price excluding the GST [12], and Manitoba’s RST on the price before the GST [13].

Tax inside a price

Remove GST mode

Price

the price including tax, after the discount

Tax

GST: CGST and SGST together, or IGST, in India; HST, or GST with the provincial tax, in Canada

Taxable value

the price before tax

Rate

the whole rate, every tax on the price together, in percent

Each tax inside the price is Price × its own rate ÷ (100 + Rate), rounded to the cent, so a price such as an MRP or a shelf price is kept exactly. In India within a state, CGST and SGST are each worked with half the rate; in Canada, GST and the provincial tax each with its own. At one rate this is a fraction of the price: 1/11 at Australia’s 10%, 3/23 at New Zealand’s 15% and 9/109 at Singapore’s 9%.

Source: Rule 35 of the CGST Rules [4]: the tax in a value inclusive of taxes is that value × the tax’s rate ÷ (100 + the sum of the rates). The ATO’s “dividing the price by 11” [17], Inland Revenue’s 3/23 of $100, or $13.04 [19], and IRAS’s 9/109 × $90 = $7.43 [21] are the same rule at one rate.

An invoice

Invoice mode

Line amount

one line’s quantity × unit price, less its discount

Tax

the line’s taxes together: CGST and SGST, or IGST, in India

Rate

the line’s whole rate, in percent

Taxable value

each line’s value before tax

Invoice total

what the invoice comes to

Each line is worked as one amount, as above: with unit prices before tax (Add GST) the line amount is its taxable value; with unit prices that include it (Remove GST), the tax is taken out of it. The invoice’s taxable value and each tax are the lines’ added up, shown by rate. In India the total is then rounded to the nearest rupee, fifty paise up, and the difference shown as the round-off; elsewhere it stays to the cent.

Source: Rule 46 of the CGST Rules [7] lists what a tax invoice shows, among them the quantity, the taxable value after any discount, and the rate and amount of each tax. NIC’s e-invoice rules [8] work each item the same way: taxable value = gross amount − discount, then CGST and SGST each the taxable value × the GST rate ÷ 2 within a state, or IGST × the whole rate between states. The ATO’s taxable sale rule [18] and IRAS’s first method [22] also work each item’s tax and add them.

Discount before the tax

Every mode

A discount given at the time of the sale and shown on the invoice comes off before the tax, so the tax is charged on the price after it. With Remove GST, it comes off the price that includes the tax.

Source: Section 15(3)(a) of the CGST Act [5], for India. CalcTrail takes a discount off the same way elsewhere.

Rounding

Every mode

Each tax is rounded to the cent (the paisa in India), half up, before the figures are added, so the taxable value, the tax and the total shown add up. In India the law rounds the tax payable to the nearest rupee, and an invoice’s total is rounded to the nearest rupee, fifty paise up, the difference shown as the round-off. Elsewhere the total stays to the cent.

Source: Section 170 of the CGST Act [6] rounds the tax payable to the rupee, fifty paise and up rounding up; NIC's e-invoice rules [8] let a round-off of −₹99.99 to +₹99.99 adjust an invoice total, and rounding it to the nearest rupee is CalcTrail's choice. The ATO rounds one sale's GST to the nearest cent, half a cent up, and lets several be rounded by the taxable sale rule or the total invoice rule [18]. IRAS accepts 9% on each item or on the total, the total GST to the nearest cent [22]. Rounding each tax to the cent is CalcTrail's own rule in New Zealand and Canada.

The rates on the picker

Every mode

India: 18% standard, 5% merit, 40% de-merit and nil; 3% for gold, silver and jewellery, 1.5% for cut and polished diamonds and 0.25% for rough diamonds and precious stones; 12% and 28% for a supply whose time of supply was before 22 September 2025. Australia 10%, New Zealand 15% and Singapore 9%, each with 0%. Canada by province: HST of 13% in Ontario, 14% in Nova Scotia and 15% in New Brunswick, Newfoundland and Labrador and Prince Edward Island. GST of 5% with PST of 7% in British Columbia, RST of 7% in Manitoba, PST of 6% in Saskatchewan and QST of 9.975% in Quebec; GST of 5% alone in Alberta and the three territories.

Source: India: the 56th GST Council [1] and Notification 9/2025-Central Tax (Rate) [2], checked October 15, 2026. Canada: the CRA's table of rates by province [9] and its place-of-supply rules [10], Saskatchewan [14] and British Columbia's Provincial Sales Tax Act, section 34 [15]; Australia [16], New Zealand [19] and Singapore [20]; checked October 16, 2026.