GST Calculator

Last updated: Jul 22, 2026 | Reviewed by Calkulator Team | 2 min read

Tax

Calculate GST for any invoice — exclusive or inclusive

Whether you are a business owner raising invoices or a buyer verifying charges, knowing the exact GST split matters. A ₹50,000 service at 18% GST means ₹9,000 tax (₹4,500 CGST + ₹4,500 SGST for intra-state).

For inter-state supplies, GST is collected as IGST instead of CGST+SGST — the total amount remains the same.

GST Details

Amount (₹)

₹

Enter the base or total amount

GST Rate

Calculation Type

Exclusive — GST added on top of entered amount

Transaction Type

GST Formulas

Exclusive: GST = Amount × Rate / 100

Inclusive: Base = Amount × 100 / (100 + Rate)

Intra-state: CGST = SGST = GST / 2 | Inter-state: IGST = GST

GST Amount

₹—

—

Total (GST-inclusive)

₹—

Pre-GST + Tax

Pre-GST Amount

₹—

Base taxable value

GST Rate Applied

—

Tax slab

CGST (Central)

₹—

50% of GST

SGST (State)

₹—

50% of GST

GST %

—%

Pre-GST Amount ₹—

GST Amount ₹—

Live Result Illustration

Visual summary — updates instantly as you enter values above

LIVE

Real-Life Guide to Using the GST Calculator

GST at 5%, 12%, 18%, 28% slabs. Use the examples and checks below to turn the number into a practical decision.

When this calculator is useful

Business owners, freelancers issuing invoices, and shoppers checking a bill use this to work out the GST amount and final price at a given rate slab, either adding GST to a base price or extracting it from a GST-inclusive price.

For most people, the best way to use the GST Calculator is to try the real case first, then change one input at a time. That makes the trade-off visible. For example, with a loan calculator you can change tenure while keeping the same rate; with an investment calculator you can change return assumption while keeping the same monthly contribution; with a health, education or measurement calculator you can check how much one input changes the final category.

The result should answer a practical question: Can I afford this? How much should I save? Is this score enough? Is this measurement within range? What is the safer or cheaper option? If the output does not answer the decision clearly, adjust the inputs until the scenario matches your real situation.

Real-Life Example

Retailer pricing at 18% GST: A retailer sells a product for a base price of ₹2,000 before tax, and the applicable GST slab for that product is 18%.

1GST amount = ₹2,000 × 18% = ₹360, split as ₹180 CGST and ₹180 SGST for an intra-state sale, making the final invoice price ₹2,360. If the retailer instead had a GST-inclusive price of ₹2,360 and needed to back out the tax, they would divide by 1.18, arriving at the same ₹2,000 base and ₹360 tax.

2Now change one input, such as rate, time, quantity, unit or score, and compare the new result with the first one.

The direction of the calculation — adding tax to a base price versus extracting tax from an inclusive price — must match how the original price was quoted, or the tax figure will be wrong.

Practical Advice

Use the GST Calculator as a planning tool, not just a number generator. Write down the inputs you used, because the final answer is meaningful only when you remember the assumptions behind it.

If the decision affects money, health, tax, safety, academics or legal compliance, keep a second check ready. That second check may be a bank quote, payslip, official rule, prescription, site measurement, mark sheet or invoice.

Common Mistakes

Applying the GST rate to a price that already includes GST, effectively double-taxing the amount instead of using the reverse/exclusive calculation to extract the tax component
Not splitting the total GST into CGST and SGST (each typically half the total rate) for an intra-state sale, versus a single IGST for inter-state sales, which matters for invoice compliance even though the total tax amount is the same
Using the wrong slab for the product or service category — GST rates differ by HSN/SAC code, and rates have been revised across recent GST Council meetings, so an old cached rate can be wrong
Forgetting that some goods and services are exempt or taxed at a special/nil rate, and running them through the standard 5/12/18/28% slabs anyway
Ignoring that a business registered under the composition scheme pays GST at a flat concessional turnover-based rate instead of the standard slab rates, so this calculator does not apply to them directly

How to Interpret Results

Check whether your input price was meant to be pre-tax or tax-inclusive before reading the result — the calculator shows the GST amount and the corresponding final price, which should match the tax and total lines on a correctly issued invoice at that rate.

A good interpretation looks at both the main result and the supporting values. If a page shows totals, ratios, categories, schedules or warnings, read those together instead of focusing only on the biggest number.

GST Calculator FAQs

Useful answers for interpreting the output, avoiding mistakes and using the result responsibly.

What does this GST calculator do?

It computes the GST amount and total price for a given base price and rate slab (commonly 5%, 12%, 18%, or 28%), and can also work in reverse to extract the base price and tax amount from a price that already includes GST.

How do I know which GST rate applies to my product or service?

GST rates are assigned by HSN code for goods and SAC code for services, and these have been revised multiple times by the GST Council since GST was introduced — check the current rate for your specific HSN/SAC code on the official GST portal rather than assuming a rate from memory, since this calculator only applies whatever rate you select.

What is the difference between CGST, SGST, and IGST that the calculator might show?

For a sale within the same state, the total GST is split equally between CGST (central) and SGST (state); for a sale between two different states, the full amount is charged as IGST (integrated) collected by the centre and apportioned to the destination state. The total tax rate and amount are the same either way — only the split and reporting differ.

Why does my supplier's invoice show a slightly different GST amount than this calculator?

Small differences usually come from rounding rules applied per invoice line versus rounding the total, or from a different rate being applied to a specific line item than the flat rate you selected here. For any discrepancy on an actual invoice, treat the supplier's tax invoice as the authoritative figure and use this tool only for quick estimates.

Does this calculator work for businesses under the GST composition scheme?

No, composition scheme taxpayers pay GST at a small flat percentage of their turnover (rates differ for traders, manufacturers, and restaurants) instead of charging the standard slab rates on each invoice, and they cannot charge or collect GST separately from customers — this standard-rate calculator does not reflect that scheme.

Are all goods and services taxed under one of the four common slabs?

No, some essential goods and services are exempt or nil-rated, some fall under special rates outside the common 5/12/18/28% structure (like on gold or specific sin/luxury goods), and rates continue to be revised — always verify against the current official rate schedule rather than assuming every item fits the standard slabs.

I run a small business — how does this help me price my products?

Use it to quickly work out what to charge on top of your cost price so your invoice correctly reflects the tax component, and to reverse-check that a competitor's or supplier's all-inclusive price is charging the rate you expect for that category of goods or services.

What should I do if I'm unsure which rate applies to my specific product?

Look up the exact HSN or SAC code for your product or service on the GST portal's rate finder, or check with a GST practitioner, since misclassifying the rate on invoices can lead to short payment of tax, interest, and notices later even if the calculator math itself was correct.

What is a GST Calculator?

GST (Goods and Services Tax) replaced multiple indirect taxes in India in 2017. It has four main slabs: 5%, 12%, 18%, and 28%. When a business sells goods or services, it adds GST on top of the base price — the buyer pays the GST-inclusive price.

For intra-state transactions, GST is split equally between CGST and SGST (e.g., 18% GST = 9% CGST + 9% SGST). For inter-state transactions, IGST applies at the full rate. This calculator handles both inclusive and exclusive calculations across all GST slabs.

Example Calculation

Scenario: Samsung LED TV, base price ₹35,000, GST 28% (intra-state)

1GST = ₹35,000 × 28% = ₹9,800

2Total = ₹35,000 + ₹9,800 = ₹44,800

3CGST (14%) = ₹4,900 | SGST (14%) = ₹4,900

✓ Customer pays ₹44,800 | CGST ₹4,900 + SGST ₹4,900 deposited with govt.

Frequently Asked Questions

GST explained for Indian businesses and consumers

What are the main GST slabs in India?

GST has four main slabs: 5% (essential goods — packaged food, medicines), 12% (processed food, computers), 18% (most services, electronics, restaurants), and 28% (luxury goods — cars, tobacco, aerated drinks). Many essentials like fresh vegetables, milk, and health services are at 0% (exempt).

What is the difference between CGST, SGST, and IGST?

For intra-state (same state) transactions, GST is split equally between CGST (central, 50%) and SGST (state, 50%). For inter-state transactions, the full GST is collected as IGST by the central government and later shared with the destination state.

Who is required to register for GST?

Businesses with annual turnover above ₹40 lakh (goods) or ₹20 lakh (services) must register. Mandatory registration regardless of turnover: e-commerce sellers, inter-state suppliers, reverse charge recipients, and businesses making TCS/TDS deductions under GST.