How it works
- You set the amount before tax and the GST rate with two sliders. The rate slider steps in whole percent so the standard slabs are easy to land on exactly.
- Tax is amount × rate ÷ 100 and the total is the amount plus that tax. Both figures are recomputed on every input event, with no submit step.
- The CGST row shows half the tax. For an intra-state supply the tax splits equally into central and state components, and the invoice has to show them as separate lines — the total is the same, but a return filed with a single combined figure is wrong.
- The proportion bar splits the total into the base and the tax, from the same two numbers shown in the rows.
- Nothing you enter leaves the page. No cookie, no storage, no analytics event carrying your amounts.
Limitations
It applies a single rate to the whole amount. Real invoices frequently mix slabs — goods at twelve percent and a service line at eighteen on the same bill — and each line has to be calculated separately, then summed. Running one calculation on the invoice total will give you a number that does not reconcile with any line on it.
The CGST half-share assumes an intra-state supply. When the place of supply is a different state, the whole amount is IGST instead and there is no split at all. Getting this wrong on a return is a common and annoying correction, and the tool cannot tell which case you are in because it does not know where either party is.
This calculates GST forward, from a base amount. Extracting the tax already inside a tax-inclusive price is the reverse operation and needs a different divisor — for an eighteen percent rate you divide the inclusive price by 1.18 to get the base, not subtract eighteen percent from it. Subtracting eighteen percent from an inclusive price gives the wrong answer, and it is the most common mistake in this area.
Zero-rated and exempt are not the same thing, even though both produce zero tax here. Zero-rated supplies allow input tax credit and exempt supplies do not, which changes what you can claim. The arithmetic is identical; the return is not.
Questions
Are my figures saved anywhere?
No. The numbers exist only in this page while it is open. There is no account, no history, and no analytics event carrying your amounts.
How accurate is the result?
The arithmetic is exact. Whether it is the right arithmetic depends on facts the page does not know — your place of supply, whether the price you started from already includes tax, and whether the invoice mixes slabs.
How do I remove GST from a price that already includes it?
Divide rather than subtract. At eighteen percent, the base is the inclusive price divided by 1.18, and the tax is the difference. Subtracting eighteen percent from the inclusive price gives a figure that is too low, because that eighteen percent was calculated on the larger number.
Why is the CGST row half the tax?
Because an intra-state supply splits the tax equally into CGST and SGST, and the invoice must show both. If the supply crosses a state boundary it is IGST at the full rate with no split, and this row does not apply.
Do I need an account?
No. There is no sign-up, no email step and no usage counter. The tool is paid for by the ads on this page.
When people use it
The everyday case is writing or checking a single invoice. A freelancer quoting a fee needs the inclusive figure to put in an email; a small business owner checking a supplier's bill wants to know whether the tax line is right. One rate, one amount, and the answer has to be exact because it goes on a document.
The second case is pricing. Deciding what to charge so that the number the customer sees is round, or so that the amount landing in your account after tax covers the cost, means running the arithmetic in both directions a few times. The sliders make that iteration quick, and the base-versus-tax bar shows immediately how much of a quoted price is not yours.
An invoice rarely travels alone — the tax invoice, the annexure and the delivery note usually have to reach the client as one attachment. Merge PDF combines them in the order you set, in the browser, with nothing uploaded.
How it compares
Against an accounting package, this is a scratchpad and nothing more — it does not know your registration, cannot tell intra-state from inter-state, and produces no record. That is fine for checking one figure and wrong for filing. Where it beats the software is speed and privacy for a single question: your client's fee never goes into a cloud ledger to answer 'what is this plus eighteen percent'.