GST calculator, inclusive and exclusive
Add GST to a base price or strip it out of a total, with the CGST, SGST and IGST split worked out for you.
Runs entirely in your browser. Your figures are never sent anywhere.
Direction
How to use the GST calculator
- Choose your direction. Add GST starts from a base price and works out the total. Remove GST starts from a total that already includes tax and works backwards to the base.
- Enter the amount. The label above the box changes to tell you which figure it expects, so you cannot enter the wrong one by mistake.
- Pick a rate from the chips, or type any rate into the box below for a case the presets do not cover.
- Select whether the transaction is within one state or across state lines. That decides whether the tax splits into CGST and SGST, or appears as a single IGST line.
What you can use it for
Working backwards from an inclusive price is the calculation people get wrong most often. If a bill is 11,800 including 18% GST, the base is not 11,800 minus 18%. It is 11,800 divided by 1.18, which gives 10,000. Subtracting the percentage gives 9,676 and understates the base by over three hundred rupees.
Freelancers and consultants raising invoices need the CGST and SGST split written out separately. A GST invoice for a client in your own state must show both halves as individual lines; showing a combined 18% is not a compliant invoice, and clients claiming input credit will send it back.
Pricing decisions depend on which side of the tax you quote. Selling to consumers, you usually advertise an inclusive price and need to know your actual revenue after tax. Selling to businesses, you quote exclusive because they reclaim the tax. Getting this backwards costs you the tax amount out of your own margin.
Checking a supplier invoice takes seconds and occasionally catches real errors. Enter the base and the rate, and confirm their total matches. Rounding differences of a rupee are normal; anything larger usually means the wrong rate was applied to a line item.
Things to know about GST in India
India uses four main slabs — 5, 12, 18 and 28% — plus a nil rate for essentials and a special rate for precious metals. Which slab applies depends on the HSN or SAC code of what you are selling, not on your choice. Most professional services fall at 18%.
CGST and SGST are always an exact half each of the total rate. An 18% intra-state supply is 9% CGST to the centre and 9% SGST to the state. For a supply crossing state lines the whole 18% is charged as IGST instead, which the centre later apportions. The customer pays the same either way.
Registration is mandatory above an annual turnover of 40 lakh for goods and 20 lakh for services in most states, with lower thresholds in special category states. Anyone selling through an e-commerce platform must register regardless of turnover.
Input tax credit is the mechanism that stops tax compounding at each stage. A registered business offsets the GST it paid on purchases against the GST it collected on sales, and remits only the difference. This is why B2B buyers care so much about receiving a properly formatted invoice with your GSTIN on it.
Frequently asked questions
Divide the inclusive total by (1 + rate/100). For 18%, divide by 1.18. The GST portion is the total minus that result. Subtracting 18% from the total is the common mistake and always gives a base that is too low, because the 18% was calculated on the smaller base, not on the total.
CGST goes to the central government and SGST to the state, split evenly, and both apply when buyer and seller are in the same state. IGST is a single charge at the full rate for supplies between different states. The total tax is identical in both cases — only the destination of the money differs.
It depends on the HSN code for goods or the SAC code for services, both published by the GST Council. Most services are 18%. Rates do change at Council meetings, so check the current official notification rather than relying on a figure you remember from last year.
Generally yes if annual turnover exceeds 40 lakh for goods or 20 lakh for services, with lower limits in some states. Selling through an e-commerce marketplace requires registration at any turnover. Rules have exceptions, so confirm with a chartered accountant for your specific situation.
No. It performs the arithmetic accurately, but which rate applies, whether you must register, and how to claim input credit are questions that depend on your circumstances. Nothing here is tax or legal advice — consult a qualified professional before filing.