Service Charge & GST Formula Explained, With Examples
Every service charge & gst result comes from one formula. Once you understand what goes into it, you can sanity-check any figure you are given, whether by an employer, a bank, a teacher or another website.
The formula
Total = menu price × 1.10 × 1.09 (≈ 1.199).
What each input means
- Menu total (S$): the value you enter in the calculator.
Example
For example, with these inputs:
- Menu total (S$): 80
the calculator returns:
- Service charge (10%): S$8.00
- GST (9% on food + service): S$7.92
- Total bill: S$95.92
How the result changes
The table keeps the other inputs at their example values and changes menu total (s$).
| Menu total (S$) | Service charge (10%) | GST (9% on food + service) | Total bill |
|---|---|---|---|
| 80 | S$8.00 | S$7.92 | S$95.92 |
| 40 | S$4.00 | S$3.96 | S$47.96 |
| 60 | S$6.00 | S$5.94 | S$71.94 |
| 100 | S$10.00 | S$9.90 | S$119.90 |
| 120 | S$12.00 | S$11.88 | S$143.88 |
Why it matters
Singapore's tax system is simple by global standards, but the progressive bands, reliefs and the 9% GST still trip people up. A quick calculation helps you set aside the right amount before IRAS sends your notice of assessment, or check that a bill has been worked out correctly.
Singapore taxes individuals on income earned in Singapore, with progressive rates for residents that start at 0% on the first S$20,000 of chargeable income and rise to 24% on income above S$1 million. Tax is assessed a year in arrears: income earned in 2025 is assessed in Year of Assessment 2026.
IRAS issues a notice of assessment, usually from April onwards, and tax is due within a month, although most people opt for interest-free GIRO instalments. Estimating your bill early means you can budget for it instead of being surprised.
You are generally a tax resident if you are a citizen or PR who normally lives here, or a foreigner who has stayed or worked in Singapore for at least 183 days in the calendar year. Non-residents do not get personal reliefs and are taxed differently, which is why residency status matters so much for expatriates.
Related calculations
- Non-Resident Income Tax Calculator: Non-resident employees pay the higher of 15% flat or progressive resident rates on employment income, without personal reliefs.
- GST Calculator (9%): Adds Singapore's 9% Goods and Services Tax to a price.
- Remove GST Calculator (Reverse GST): Works backwards from a GST-inclusive price to show how much of it is GST.
- SRS Tax Savings Calculator: Shows how much tax you save by contributing to the Supplementary Retirement Scheme.
Use the Service Charge & GST Calculator to plug in your own numbers.
Run your own numbers: Service Charge & GST Calculator