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💼GST Calculator
GST Calculation Guide
Interstate vs Intrastate GST
When goods are sold within the same state:
GST is split equally between CGST and SGST
Example: For 18% GST, CGST = 9% and SGST = 9%
When goods are sold between different states:
Full GST is charged as IGST
Example: For 18% GST, IGST = 18%
GST Calculator
This GST calculator adds tax to a base price or extracts it from a tax-inclusive total at any rate — for example, ₹10,000 plus 18% GST becomes ₹11,800, of which ₹1,800 is tax. It handles Indian slab rates as well as international rates such as Australia (10%), New Zealand (15%) and Singapore (9%), so one tool covers quoting, invoicing and reconciliation.
Key facts
- India introduced GST on 1 July 2017; the original slab structure was 0%, 5%, 12%, 18% and 28%, rationalised in September 2025 to main rates of 5% and 18% plus a 40% demerit rate.
- To remove 18% GST, divide the inclusive price by 1.18 — the tax equals 18/118 (about 15.25%) of the inclusive amount, not 18% of it.
- GST rates elsewhere: Australia 10%, New Zealand 15%, Singapore 9% (since January 2024) and Canada 5% federal GST.
- On an intra-state Indian sale taxed at 18%, the invoice shows 9% CGST plus 9% SGST — two equal halves of the same tax.
What is the GST Calculator?
Goods and Services Tax (GST) is a broad-based consumption tax levied on the supply of goods and services at each stage of the sales chain, with credit for tax already paid on inputs. India introduced GST on 1 July 2017, replacing a patchwork of central and state levies. Because the tax is collected by sellers but ultimately borne by the final consumer, businesses constantly need to convert between tax-exclusive and tax-inclusive prices — which is exactly what this calculator automates.
How does the GST Calculator work?
Two formulas cover every GST problem. To add tax: GST = Base × Rate and Total = Base × (1 + Rate), so ₹10,000 at 18% gives ₹1,800 tax and ₹11,800 total. To remove tax from an inclusive price: Base = Total ÷ (1 + Rate), so ₹11,800 ÷ 1.18 returns the ₹10,000 base. The common mistake is subtracting 18% from the inclusive total — that yields ₹9,676, not ₹10,000, because the percentage bases differ. For intra-state Indian supplies the calculator can also split the tax equally into CGST and SGST halves.
What is the GST Calculator formula?
- Base – pre-tax amount
- Rate – decimal (e.g. 0.18 for 18%)
GST on a ₹10,000 price at common rates
| GST rate | Tax added to ₹10,000 base | Tax-inclusive total | Base inside a ₹10,000 inclusive price |
|---|---|---|---|
| 5% | ₹500 | ₹10,500 | ₹9,523.81 |
| 9% (Singapore) | ₹900 | ₹10,900 | ₹9,174.31 |
| 10% (Australia) | ₹1,000 | ₹11,000 | ₹9,090.91 |
| 12% | ₹1,200 | ₹11,200 | ₹8,928.57 |
| 15% (New Zealand) | ₹1,500 | ₹11,500 | ₹8,695.65 |
| 18% | ₹1,800 | ₹11,800 | ₹8,474.58 |
| 28% | ₹2,800 | ₹12,800 | ₹7,812.50 |
How do you use the GST Calculator?
- Enter the amount.
- Pick the GST rate.
- Choose add or remove.
- Read the breakdown.
Worked example
| Scenario | $1,000 + 18% GST |
| Calculation | 1000 × 0.18 = 180 |
| Result | GST $180; total $1,180. |
Common use cases
Tips & best practices
Display tax-exclusive prices to businesses; tax-inclusive prices to consumers.
Frequently asked questions
Multiply the base price by the GST rate expressed as a decimal, then add the result to the base. For ₹10,000 at 18%, the GST is ₹10,000 × 0.18 = ₹1,800, making the invoice total ₹11,800. The same one-step shortcut works at any rate: multiply the base by (1 + rate), so ₹10,000 × 1.18 = ₹11,800.
Divide the inclusive price by (1 + rate) — never subtract the percentage. A ₹11,800 total at 18% GST contains a base of ₹11,800 ÷ 1.18 = ₹10,000 and tax of ₹1,800. Subtracting 18% from ₹11,800 would wrongly give ₹9,676, because 18% of the larger inclusive figure is more than the tax actually charged. The tax share of an 18%-inclusive price is 18/118, about 15.25%.
India levied GST at four main slabs — 5%, 12%, 18% and 28% — from July 2017, with 0% on many essentials; in September 2025 the GST Council approved consolidating these into two principal rates of 5% and 18%, plus a 40% rate for selected luxury and sin goods. Because rates are periodically revised, this calculator accepts any custom percentage, and the current schedule is published by CBIC at cbic-gst.gov.in.
CGST and SGST are equal halves of the GST charged on supplies within one Indian state, while IGST is the single combined tax on supplies between states. An 18% intra-state sale is billed as 9% CGST (to the centre) plus 9% SGST (to the state); the same sale across state lines is billed as 18% IGST. The total tax paid by the buyer is identical either way.
Yes in substance — both are multi-stage consumption taxes with input-tax credit, and the label simply varies by country. Over 170 countries operate a VAT or GST system: the EU uses VAT (rates commonly 17–27%), while India, Australia (10%), New Zealand (15%), Singapore (9%) and Canada (5% federal) call it GST. Mechanically, this calculator works identically for either name.
GST is charged on the discounted transaction value when the discount is shown on the invoice at the time of sale. If a ₹10,000 item carries a 10% invoice discount, GST at 18% applies to ₹9,000, giving ₹1,620 tax and a total of ₹10,620. Post-sale discounts not recorded on the invoice generally cannot reduce the taxable value under Indian GST rules.