Which rate applies to my product?

This calculator will not tell you. It takes whatever rate you pick and does the arithmetic on it. The rate for a particular product comes from the current CBIC notification or from your accountant, and picking the wrong one is not an error any calculator can catch.

Why is 18 percent of my settlement amount the wrong tax figure?

Because the tax is already inside that amount. Taking 18 percent of an inclusive number overstates the tax by roughly 18 percent of the tax. Use Remove GST on any figure a customer has already paid, and Add GST only on a taxable value.

Does it handle compensation cess?

Yes, as a separate percentage on the same taxable value. It goes on top in the Add direction and comes out alongside the GST in the Remove direction, since an inclusive price carries the cess in it too. Leave it at zero if your goods do not attract any.

Why do CGST and SGST sometimes differ by a paisa?

Because half of an odd number of paise is not a whole number of paise. The tax is rounded once, then the second half is taken as the remainder of the first, so the two lines always add back to the tax figure printed beside them - which is what an invoice has to show.

Can I use a rate that is not one of the buttons?

Yes. Pick Custom and type it to two decimal places. That covers rates the slab chips do not carry and lets you work through something your adviser has told you applies, rather than being stuck with a fixed list of eight.

GST calculator, both directions

Putting tax on top of a price is easy arithmetic. Taking it back out of a price that already contains it is where the mistakes happen, and a marketplace settlement line is always the second kind. Eighteen percent of 1,180 is 212.40, but 1,180 does not contain 212.40 of tax: the taxable value is 1,000 and the tax is 180.

This does both directions from the same field. Type the amount, say whether tax is already inside it, pick a rate, and the breakdown comes back the way an invoice has to show it - taxable value, the tax split, cess if any, and the total. What it will not do is choose the rate for you.

Open the GST calculator Needs an account. The trial is free and takes a WhatsApp code.

How it works

Choose a direction. Add GST when the amount you have is before tax. Remove GST when it is an MRP, a settlement figure, or anything a customer has already paid in full.
Type the amount and pick the rate. The chips cover 0, 0.25, 3, 5, 12, 18, 28 and 40 percent, and Custom takes anything else to two decimal places. Compensation cess sits beside it and stays at zero unless your goods attract it.
Say where the supply is going. Same state splits the tax into CGST and SGST at half each; another state shows one IGST line. Reverse charge adds the declaration an invoice carries when the buyer pays the tax instead of you.
Copy the breakdown. Copy breakdown hands you the whole table as plain text with the amounts lined up in a column, ready to paste into a message, a sheet or an email to your accountant.

What it handles

Inclusive amounts handled as base = total x 100 / (100 + rate + cess), with the working printed on the page so you can check it against your own
Cess kept in the divisor when stripping tax, because an inclusive price carries the cess as well
CGST and SGST split so the two halves add back to the tax line exactly - a tax of 180.05 becomes 90.02 and 90.03, not 90.03 twice
Rounding to the nearest paisa, half away from zero, so 1.005 lands on 1.01 instead of falling to 1.00 the way plain floating point does
Amounts read as you type them, commas, rupee sign and the Indian 1,20,000 grouping included
A reverse charge notice with the wording your invoice needs when the buyer is the one paying

Your files stay on your computer

This runs inside your browser tab. The file is read and written on your own device and is never uploaded — not the order PDF, not the customer names and addresses printed on it. There is no upload endpoint to send it to.

Questions

Which rate applies to my product?: This calculator will not tell you. It takes whatever rate you pick and does the arithmetic on it. The rate for a particular product comes from the current CBIC notification or from your accountant, and picking the wrong one is not an error any calculator can catch.
Why is 18 percent of my settlement amount the wrong tax figure?: Because the tax is already inside that amount. Taking 18 percent of an inclusive number overstates the tax by roughly 18 percent of the tax. Use Remove GST on any figure a customer has already paid, and Add GST only on a taxable value.
Does it handle compensation cess?: Yes, as a separate percentage on the same taxable value. It goes on top in the Add direction and comes out alongside the GST in the Remove direction, since an inclusive price carries the cess in it too. Leave it at zero if your goods do not attract any.
Why do CGST and SGST sometimes differ by a paisa?: Because half of an odd number of paise is not a whole number of paise. The tax is rounded once, then the second half is taken as the remainder of the first, so the two lines always add back to the tax figure printed beside them - which is what an invoice has to show.
Can I use a rate that is not one of the buttons?: Yes. Pick Custom and type it to two decimal places. That covers rates the slab chips do not carry and lets you work through something your adviser has told you applies, rather than being stuck with a fixed list of eight.

Related tools

Open the GST calculator