How to calculate GST in Excel and Google Sheets

Excel & Google Sheets

=A2*B2

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Verified example

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=A2*B2→100

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Formula

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1Column A = Pre-tax Amount, Column B = GST Rate (e.g., 0.10 for 10%, 0.18 for 18%).
2GST amount: =A2*B2 in C2.
3Total including GST: =A2*(1+B2) in D2.
4To extract GST from a GST-inclusive price (reverse GST): =A2*B2/(1+B2).
5Round results: =ROUND(A2*B2,2).

For India's GST with separate CGST and SGST, split the rate: if total GST is 18%, each component is 9%. Calculate each half separately for invoice display.

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Divide by (1 + GST rate): =A2/(1+B2). For example, $110 at 10% GST gives $110/1.10 = $100.

Rates vary by country: Australia 10%, India 5%/12%/18%/28%, Canada 5%, New Zealand 15%.

Written and reviewed by FormulaCraft Team. Each formula on this page is run through our verification engine before publishing.

Last reviewed: May 28, 2026