GST Splitter

Online GST calculator India: from one amount to a complete breakdown

Preparing a quotation, checking a supplier bill or reviewing an e-commerce selling price often starts with one number. That number might be a price before tax, a final invoice amount, or the GST already shown on a document. AllFast GST Splitter connects all three. Enter the number you know and the other fields update immediately, with a clear separation between taxable value, tax and total. This online GST calculator for India is useful for business owners, accountants, CA teams, freelancers and sellers who want a quick arithmetic cross-check.

The initial 18% is an example rate, not a product classification. Choose the percentage that applies to your transaction, then select the appropriate supply type. The calculation covers one taxable amount at one GST rate. For an invoice with several rates, calculate each group separately and reconcile the groups with your billing software.

How to use the three linked GST inputs

1. 01
   Choose a rate.

   Use a preset or open Custom Rate %. The custom field accepts 0–100% with up to two decimal places, including 0%, 7.5%, 15% and 40%.

2. 02
   Enter the amount you know.

   Use Amount without GST for a taxable value, Amount with GST for an inclusive price, or GST Tax Amount to recover the underlying value.

3. 03
   Choose the split.

   Intra-State displays CGST and SGST / UTGST. Inter-State displays the same total tax as IGST.

4. 04
   Review and save.

   Copy an individual card or the full breakdown, download a PNG or text slip, or open the print dialog to print or save a PDF.

The most recently edited amount drives subsequent rate changes. For example, if you enter a total of ₹1,180 and then change the rate, the total stays fixed while the taxable value and GST adjust. If you instead edit the taxable value, that value stays fixed when you choose a different rate. Amounts and calculated totals are limited to ₹10,00,00,00,00,000.00. Empty, negative, malformed or over-limit entries pause the results until corrected.

GST inclusive exclusive formula, explained with examples

Exclusive GST: add tax to the taxable value

A GST-exclusive price leaves the tax outside the quoted amount. Let B represent the taxable value and r represent the percentage rate, such as 18 for 18%. Multiply B by r and divide by 100 to obtain GST. Add that tax to the taxable value to obtain the gross amount.

For a smaller example, ₹32 before GST at 18% gives ₹5.76 of tax and ₹37.76 in total. The amount-in-words line reads “Rupees Thirty-Seven and Seventy-Six Paise”. It follows the total invoice field and uses Indian number groups, including lakh and crore.

Reverse GST calculator: remove included tax

A GST-inclusive total already contains the taxable value and the tax. Removing GST therefore requires division by the combined base-and-tax multiplier. Deducting the rate directly from the inclusive total applies the percentage to the wrong base.

Before rounding, the equivalent direct expression is GST = Total × r / (100 + r). This reverse GST calculator rounds the recovered taxable value to paise and subtracts it from the entered total, so the displayed values always reconcile. It preserves the total you supplied.

Work backwards from the tax amount

If a document gives you the tax but not the base, enter the tax amount and select the known rate. For a positive rate, Taxable value = GST × 100 / r. For example, ₹180 GST at 18% implies ₹1,000 taxable value and ₹1,180 gross. At 0%, tax alone cannot identify a taxable value: infinitely many base amounts produce zero tax. The tool therefore makes the tax field read-only at 0% and asks you to use the base or total instead.

HSN/SAC slab reference: check the supply date and description

HSN identifies goods; SAC identifies services. A heading is a starting point, and the complete description, conditions and effective notification determine treatment. The 2025 GST Council material describes major rate changes, including the 5% and 18% structure and a special 40% rate. Its FAQs give 22 September 2025 as the effective date for most changes, with specified exceptions. Preset buttons remain useful for historic invoices and arithmetic comparisons; they are not a complete current tariff.

For current classification, consult CBIC Tax Information and the effective notifications. The table is illustrative, not an exhaustive HSN lookup. For goods spanning a rate change, check the applicable time-of-supply provisions rather than relying on the date printed on an old price list.

CGST SGST IGST splitter for business transactions

For an ordinary intra-State supply, the supplier location and place of supply are in the same State or Union territory, subject to statutory exceptions. GST is generally divided into CGST and SGST, or UTGST where applicable. An 18% combined rate is displayed as 9% CGST and 9% SGST / UTGST. On ₹1,000 taxable value, these components are ₹90 each.

For an ordinary inter-State supply, supplier location and place of supply are in different States or Union territories, and IGST generally applies. At 18%, the same ₹1,000 base gives ₹180 IGST. Place-of-supply rules and exceptions, including SEZ and import/export treatment, matter; the buyer’s address alone is not always sufficient. This CGST SGST IGST splitter changes the presentation of the tax, not its combined amount, and does not determine legal place of supply.

Rounding, receipts and e-commerce checks

The engine uses whole paise and integer rate arithmetic. Positive half-paise ties round upwards. In an intra-State split, CGST receives the rounded half and SGST / UTGST receives the remaining paise. If GST is ₹0.05, the cards show ₹0.03 and ₹0.02. The rates still represent equal halves; the one-paisa difference is a display reconciliation adjustment, not a different tax rate.

Line-by-line invoice rounding can differ from calculating tax on a combined subtotal. Discounts, delivery charges, mixed-rate baskets, compensation cess, marketplace deductions and other adjustments are outside this single-value calculation. E-commerce settlement amounts should therefore be reconciled separately from the taxable sales value. A CA or accounts team can use the results as a working check alongside the original transaction documents.

The downloaded slip records the rate, calculation source, supply view, values, amount in words and formula. It is a calculation summary, not a statutory tax invoice. Copy and download run in the browser. Share creates a link containing the entered amount, rate and selected view; anyone receiving that link can see those values. The calculator itself does not send calculations to an API, but a shared URL can appear in browser history and server logs when opened.

Frequently asked questions