GST Calculator
Calculate Goods and Services Tax for your business transactions.
Loading Smart Logic...
Quick Tip
Choose whether your amount excludes or includes GST.
About This Tool
Why use GST Calculator?
Add GST to a base amount or extract it from a total that already includes it. Adding is amount × rate ÷ 100; removing works backwards with base = total ÷ (1 + rate ÷ 100), which is the step people most often get wrong by subtracting the percentage instead.
On ₹10,000 at 18%, GST is ₹1,800 and the total is ₹11,800. Going the other way, ₹11,800 inclusive divides by 1.18 to give ₹10,000 plus ₹1,800 of tax. Subtracting 18% from ₹11,800 would give ₹9,676, which is wrong by ₹324. India's main rates are 5%, 12%, 18% and 28%, and the same arithmetic applies to VAT anywhere.
Key Benefits
Both directions
Add tax to a net price, or split an inclusive price into base and tax correctly.
Standard rate slabs
The common 5%, 12%, 18% and 28% rates are built in, and any custom rate can be typed.
Works for VAT too
The arithmetic is identical for VAT, so the tool suits any inclusive or exclusive tax rate.
How to use GST Calculator
- 1
Choose whether your amount excludes or includes GST.
- 2
Enter the amount.
- 3
Select or type the GST rate that applies.
- 4
Read the tax amount, the base amount and the total.
Best use cases
Add GST to a quote or an invoice.
Split an inclusive price into base and tax for bookkeeping.
Check the tax on a supplier bill.
Work out the pre-tax price of a retail purchase.
GST Calculator FAQs
How do I remove GST from an inclusive price?
Divide by 1 plus the rate as a decimal. At 18%, divide the total by 1.18 for the base amount; the difference is the GST.
Why can't I just subtract 18% from the total?
Because the 18% was calculated on the smaller base amount, not on the total. Subtracting it from the total always understates the base.
What are the GST rates in India?
The main slabs are 5%, 12%, 18% and 28%, with some goods at 0% or under special rates. The rate depends on the specific goods or service.
What is the difference between CGST, SGST and IGST?
Within a state the total splits equally into CGST and SGST, so 18% is 9% each. For inter-state supply the whole amount is IGST. The total the customer pays is the same either way.
Related Finance Tools
More free finance tools that work well alongside gst calculator.