GST Calculator
Add or remove GST at the rate you enter, split into the CGST, SGST, IGST or federal and provincial components an invoice shows.
Result
Enter amount to see the result.
https://calcgallery.com/consumption-tax/gst-calculator/
Results are arithmetic from the amounts and rates you enter. The site publishes no tax rate, threshold or tipping convention, and rates vary by jurisdiction and change. Check the rate on your receipt, invoice or tax authority guidance, and confirm anything that matters with a qualified adviser. Read the full disclaimer
How to use the GST Calculator
- Choose whether you are adding GST to a net amount or removing it from a gross one.
- Enter the amount and your GST rate.
- Pick the component split your invoice needs.
- Check that the components sum to the total GST — they always will.
How it is calculated
The core is identical to VAT, using the same code:
add: gross = net × (1 + rate) gst = gross − netremove: net = gross ÷ (1 + rate) gst = gross − netRemoving GST is a division. Subtracting the rate from a gross figure takes off too much, because the rate was charged on the smaller net amount.
The component split
What this page adds over the VAT one is the breakdown an invoice shows:
| Split | What it means |
|---|---|
| CGST and SGST | An intra-state supply, divided between the central and state authorities |
| IGST | An inter-state supply, charged as one integrated tax |
| Federal and provincial | A federal portion at its own rate, with the remainder provincial |
The components always sum to the total GST, to the cent, after display rounding. That matters because an invoice shows both the parts and the total, and a reader adding them up will notice if they disagree.
An odd cent is the awkward case. GST of 18.01 halves as 9.01 and 9.00, not 9.00 and 9.00. The page apportions by largest remainder so nothing is lost.
An impossible split is rejected. A federal component larger than the total rate would imply a negative provincial portion. The page says so and names what to change rather than quietly adjusting your figures.
Practical tips
Check the components against your invoice. If they do not match, the rate or the split mode is usually the difference.
Intra-state and inter-state are a place-of-supply question, not an arithmetic one. This page applies whichever you choose.
The odd cent has to go somewhere. Which component takes it is a presentational convention; what matters is that the parts and the total agree.
Reverse charge, composition schemes and exempt supplies are real and are not modelled here. This page does the tax arithmetic on a rate you supply.
With your numbers
- $1,000.00 × 1.18 = $1,180.00 gross
- Split intra-state, that is $90.00 CGST and $90.00 SGST, which sum to the GST exactly
- GST is the difference: $180.00
Quick reference
The rate and the component split are the ones you entered. No jurisdiction rate or place-of-supply rule is stored.
| Example | GST |
|---|---|
| Add 18% to 1,000, CGST/SGST | €180.00 |
| Add 18% to 1,000, IGST | €180.00 |
| Remove 18% from 1,180 | €180.00 |
| Add 5% to 500, IGST | €25.00 |
| Add 13% to 100, federal 5% | $13.00 |
| Add 15% to 250, federal 5% | $37.50 |
| Add 18% to 100.05, odd cent | $18.01 |
| Add 12% to 750, no split | $90.00 |
Common questions about the GST Calculator
- What is the difference between CGST, SGST and IGST?
- They are the components an Indian GST invoice shows. An intra-state supply splits the tax into a central portion and a state portion, conventionally half each. An inter-state supply is charged as a single integrated tax instead. The total the customer pays is the same; what differs is which authority receives it and how the invoice presents it.
- Why do the halves sometimes differ by a cent?
- Because an odd number of cents cannot be halved evenly. GST of 18.01 splits as 9.01 and 9.00. The alternative — rounding each half independently — gives 9.00 and 9.00, which is a cent short of the total on the invoice. This page apportions by largest remainder so the components always sum to the tax exactly.
- How is GST different from VAT?
- Mostly in name and in how the components are presented. Both are value-added taxes: charged at each stage of production, with businesses reclaiming the tax on their inputs. The arithmetic on this page is the same code the VAT page uses. What this page adds is the component split, which is specific to federal systems where more than one authority levies a share.
- Why is a federal component above the total rate rejected?
- Because it is not a possible invoice. If the federal portion exceeds the whole tax, the provincial portion would have to be negative. Rather than silently normalising the figures into something you did not enter, the page refuses and says which value to change.
- Does this page know my GST rate?
- No, deliberately. Rates, slabs and place-of-supply rules differ by jurisdiction and change, and a stale table on an indexed page produces confidently wrong answers. Enter the rate from your invoice or your tax authority and the arithmetic is exact.