How this gst calculator works
To add GST, GST amount = base amount x GST rate and total = base amount + GST. To remove GST from an inclusive price, base amount = inclusive price / (1 + GST rate).
Worked example
For a base amount of ?10,000 at 18% GST, the GST amount is ?1,800 and the invoice total is ?11,800. If ?11,800 is inclusive of 18% GST, the base amount is ?10,000.
Assumptions
- The selected GST rate applies to the item or service.
- No cess, rounding adjustment or invoice-level discount is included.
- The amount entered is either base value or inclusive value based on selected mode.
- Rates are user-selected because product-specific GST classification can differ.
Limitations
- QuickCalcy does not determine the correct HSN, SAC or tax classification.
- Actual invoices may include cess, shipping, discounts or rounding.
- Businesses should verify applicable rates and compliance rules before billing.
Frequently asked questions
What does this GST calculator do?
It adds GST to a base amount or extracts GST from a tax-inclusive amount.
Which GST rates are included?
The calculator includes common options: 0%, 5%, 12%, 18% and 28%.
Can I use this for invoices?
Use it for quick estimates only. GST invoices can require additional fields, classifications and compliance checks.
How do I remove GST from an inclusive amount?
Choose remove GST, enter the inclusive amount and select the rate. The tool divides by one plus the rate.
Does this include cess?
No. Any cess or special levy must be handled separately.
Is the result rounded like an invoice?
The result is an educational calculation and may not match every invoice-rounding rule.
Is data stored?
No account is required and calculations run in the browser.