🇸🇬 Singapore GST Calculator

Methodology

How this calculator works

To add GST, multiply the pre-tax amount by 9% and add it. To extract GST from an inclusive total, divide the total by 1.09 to find the base amount; the difference is GST. Taking 9% of an inclusive total would overstate the tax component.

Worked example

Reading the result

A S$100 pre-tax item becomes S$109 including GST. Reversing S$109 returns a S$100 base and S$9 GST.

Accuracy checklist

Validate your Singapore estimate

1. 1Confirm whether the amount is tax-exclusive or already tax-inclusive before entering it. Check the supply classification, selected rate, discounts, quantity and delivery treatment against Inland Revenue Authority of Singapore — current GST rates; a mathematically correct result can still be wrong when the transaction uses a reduced, zero or exempt treatment.
2. 2Keep the net price, tax amount and gross total as separate figures when checking an invoice. If several rates apply, calculate each group independently and add the subtotals instead of using one blended rate that cannot be reconciled with the invoice lines.
3. 3Treat the Singapore result as invoice arithmetic for Current 9% standard rate, not as a registration or filing decision. Confirm tax-point timing, place-of-supply rules, input-tax recovery and sector-specific treatment with the authority or a qualified adviser when those questions affect the transaction.
4. 4Save the inputs, selected options and calculation date with the result. If the estimate informs a payment, return, contract or application, rerun it when the Current 9% standard rate rules or your underlying figures change and compare the updated breakdown with the earlier version.

Common questions

Frequently asked questions

Sources and review

Author: Ezivo Calculator. Reviewed by: Ezivo Calculator technical QA. Primary reference: Inland Revenue Authority of Singapore — current GST rates. Rules reviewed 24 October 2026.