Free GST Calculator

Calculate GST
in Seconds

Work out GST inclusive or exclusive instantly, with an accurate CGST, SGST and IGST breakdown for every slab — no signup, no limits.

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Quick GST rates
  • Always free
  • No signup
  • GSTN-compliant rates

GST Calculator

Enter an amount to see the split
GST type
Base price when exclusive, final price when inclusive
Type of supply
Base amount ₹1,000.00
GST @ 18% + ₹180.00
Total payable ₹1,180.00
Your breakdown

The Full Tax Split

₹1,000.00 exclusive of 18% GST, intra-state supply

Base amount ₹1,000.00 Before tax
Total GST ₹180.00 @ 18%
CGST ₹90.00 Central · half of GST
SGST ₹90.00 State · half of GST
IGST ₹0.00 Inter-state only
Total payable ₹1,180.00 Base + GST
How it works

Three Steps,
One Answer

No spreadsheets, no formulas to remember — the calculator does the arithmetic while you read the result.

  1. 1

    Enter your amount

    Type the price you already have — the base figure or the final billed value.

  2. 2

    Pick rate & type

    Choose the slab, then say whether GST sits inside the price or gets added on top.

  3. 3

    Read the breakdown

    CGST, SGST or IGST split out instantly — ready to copy straight onto an invoice.

The maths

The Formula,
Running on Your Numbers

Both formulas update live with whatever you typed above — watch the substitution happen.

Exclusive

GST added on top

Use when your price is the base and tax goes over it.

GST amount (1,000 × 18) ÷ 100 ₹180.00
Total price 1,000 + 180.00 ₹1,180.00
Inclusive

GST already inside

Use when the price on the tag is what the customer pays.

GST amount 1,180 × [18 ÷ (100 + 18)] ₹180.00
Base price 1,180 − 180.00 ₹1,000.00

Where the tax goes. On an intra-state sale the GST splits exactly in half — CGST to the centre, SGST to your state. Sell across a state border and the whole amount becomes a single IGST line instead.

Try one

Real Bills,
Real Numbers

Tap any example — the calculator fills in and scrolls back with the answer.

The background

One Tax That
Replaced Many

GST is a single indirect tax on the supply of goods and services that swept away VAT, sales tax, purchase tax and a stack of others.

  • Charged at the point of saleThe same rules apply nationwide, in one domestic tax regime.
  • Six slabs, one system0%, 3%, 5%, 12%, 18% and 28% cover everything you can sell.
  • Underpay and it costs 18%Interest accrues on short-paid GST — worth getting the maths right.
Why this calculator

Small Tool,
Serious Engineering

Accurate

Rounded to the paisa, matching GSTN arithmetic.

Instant

Results update as you type — no page reloads.

GST compliant

Every slab kept current with GST Council notifications.

Inclusive & exclusive

Flip between both directions with one tap.

CGST + SGST

Intra-state sales split down the middle automatically.

IGST support

Cross-border supplies handled as a single tax line.

Works anywhere

Desktop, tablet and phone — same layout quality.

Beyond the calculator

How NextBill Files
GST For You

The calculator answers one question. NextBill answers the whole month.

  • Auto-fetches data straight from your invoices
  • Prepares GSTR-1, GSTR-3B & NIL returns
  • Matches sales & purchase entries
  • One-click filing from the dashboard
  • No manual work, no errors
  • 100% GSTN-compliant process
  • File monthly or quarterly with ease
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FAQ

Frequently Asked
Questions

What is GST and where does it apply?

Goods and Services Tax is an indirect tax charged on the supply of goods and services. It replaced VAT, sales tax, purchase tax and several others. The law was passed by Parliament on 29 March 2017 and came into force on 1 July 2017, creating a single domestic indirect tax charged at the point of sale across the nation.

How do I use this GST calculator?

Pick GST Inclusive or Exclusive depending on the price you have, type the amount, then choose the relevant slab from the list — there's no need to hunt for a rate finder. The result shows the base price, the GST amount and the total, updating as you type.

What is the difference between GST inclusive and exclusive?

GST inclusive means the price already contains the tax — if something costs ₹1,000 inclusive of 18% GST, the tax is already part of that ₹1,000. GST exclusive means the tax is added over the base price, so ₹1,000 exclusive of 18% GST becomes ₹1,180. Inclusive keeps things simple for customers; exclusive is clearer for tax reporting.

What are the GST inclusive and exclusive formulas?

Inclusive: GST Amount = Total Price × [GST Rate ÷ (100 + GST Rate)], then Base Price = Total Price − GST Amount. At ₹1,180 and 18%, the GST is ₹180 and the base is ₹1,000.

Exclusive: GST Amount = (Original Amount × GST Rate) ÷ 100, then Total Price = Original Amount + GST Amount. At ₹1,000 and 18%, the GST is ₹180 and the total is ₹1,180.

When is it CGST + SGST versus IGST?

If the supplier and the customer are in the same state, the tax splits evenly into CGST (to the centre) and SGST (to the state). If the sale crosses a state border, the entire amount is charged as a single IGST line instead. The calculator handles both — just switch the type of supply.

What are the current GST slabs?

The main slabs are 0% (exempt items like fresh produce and milk), 3% (gold, silver and jewellery), 5% (essentials and transport), 12% (processed foods and apparel), 18% (the standard slab covering most goods and services) and 28% (luxury and sin goods).

What happens if I pay less GST than I should?

Short payments attract interest at 18% per annum until the shortfall is cleared. That is precisely why it pays to compute the slab correctly the first time — and why NextBill applies rates automatically once a product's HSN code is saved.

Is this calculator free to use?

Yes — completely free and unlimited. There is no account to create, no card to add and no cap on how many calculations you run.

Can I use these results on a real invoice?

Absolutely. Copy or download the breakdown and place it straight onto your bill. If you'd rather skip the copying, NextBill's invoicing applies the correct CGST, SGST or IGST automatically based on your customer's state.

Does the calculator round the way GSTN does?

Yes. Values are computed at full precision and presented to two decimal places, matching the paisa-level rounding used on GST invoices and returns.

Payments and accounting, finally in sync

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GST & Invoicing?

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