Calculate GST from the transaction’s taxable value and the rate that legally applies to the specific goods or service. Then determine the place of supply: an ordinary intra-State supply is reported as CGST plus SGST (or UTGST), while an ordinary inter-State supply is reported as IGST.
For example, at an illustrative 18% rate on a taxable value of ₹10,000, the tax is ₹1,800. An intra-State invoice would normally show ₹900 CGST and ₹900 SGST/UTGST; an inter-State invoice would show ₹1,800 IGST. The 18% figure is only an arithmetic illustration, not a universal GST rate.
| # | Preview | Product | Price | |
|---|---|---|---|---|
| 1 |
|
GST Calculator with history | Buy on Amazon | |
| 2 |
|
GST Calculator | Buy on Amazon | |
| 3 |
|
GST calculator | Buy on Amazon | |
| 4 |
|
GST Calculator | Buy on Amazon | |
| 5 |
|
GST Calculator | Buy on Amazon |
As an Amazon Associate I earn from qualifying purchases.
The calculation in one minute
Use this formula after confirming the applicable rate and taxable value:
Free tools Windows power users keep installed
One-click scans. No signup required.
GST amount = taxable value × GST rate ÷ 100
The tax type is decided separately. Compare the supplier’s location with the legally determined place of supply under the applicable rules:
#1 Best Overall
- 1) Instant GST Calculations - Quickly adds and subtracts GST at 5%, 12%, 18%, 28%.
- 2)Built-in History Log – Automatically records and displays past calculations for easy tracking.
- 3)Mobile Responsive Design – Optimized for smooth use on both smartphones and desktops.
- 4)Classic Calculator Layout – Familiar button arrangement similar to physical GST calculators.
- 5) Basic Math Operations – Perform addition, subtraction, multiplication, and division with ease.
| Transaction classification | How the tax is shown | Illustrative 18% treatment |
|---|---|---|
| Ordinary intra-State supply | CGST plus SGST, or CGST plus UTGST where applicable | 9% CGST + 9% SGST/UTGST |
| Ordinary inter-State supply | IGST | 18% IGST |
Do not infer the rate from the acronym. CGST, SGST, UTGST and IGST describe how a liability is administered; they do not tell you whether the item is taxed at 5%, 12%, 18%, 28%, a concessional rate, zero rate, or is exempt. Confirm the classification, rate, exemption and conditions for the transaction date.
What CGST, SGST, UTGST and IGST mean
CGST
Central Goods and Services Tax is the central component charged on an ordinary intra-State taxable supply. It is paired with SGST or UTGST rather than charged alone in the usual domestic case.
SGST
State Goods and Services Tax is the State component of an ordinary intra-State supply when both the supplier and the legally relevant place of supply are in the same State.
Windows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallOutdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchUTGST
Union Territory Goods and Services Tax takes the place of SGST for an applicable Union Territory. The calculation principle is the same: the combined domestic rate is divided into a central component and a State/UT component.
IGST
Integrated Goods and Services Tax generally applies to an inter-State supply. In the standard structure, the integrated rate equals the combined CGST and SGST/UTGST rates. It is not an additional tax stacked on top of both components.
Five steps to calculate the correct tax
1. Identify the exact supply and its rate
Describe what is being supplied, including the relevant goods or service category, unit, quantity and any conditions attached to the entry. Consult the current official rate notification or rate table for the transaction date. The official table separates CGST, SGST/UTGST, IGST and, where relevant, compensation cess columns. A row showing 2.5% CGST, 2.5% SGST/UTGST and 5% IGST demonstrates the relationship between the columns; it does not make 5% the rate for every product.
Check whether the entry is subject to an exemption, a concessional condition, a minimum specification, a registration requirement or compensation cess. A broad product label is not enough when the rate table distinguishes categories or conditions.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →2. Establish the taxable value
For an unrelated-party sale where price is the sole consideration, the CGST Act generally uses the transaction value as the taxable base. Start with the agreed consideration, then test the statutory additions and discount rules rather than assuming that a displayed sticker price is always the base.
Rank #2
- ✔ Easy-to-use interface
- ✔ Add or remove GST with one tap
- ✔ Supports multiple GST rates (5%, 12%, 18%, 28%)
- ✔ Quick & accurate calculations
- ✔ Ideal for businesses, freelancers & individuals
Specified incidental expenses charged by the supplier can form part of the value. Amounts that the supplier is liable to pay but the recipient incurs can also be included where the valuation provision requires it. A qualifying discount may be excluded only when the statutory conditions are satisfied; a discount label by itself does not settle the treatment.
3. Determine the place of supply
Apply the transaction-specific place-of-supply rules in the IGST framework. The general pattern is:
- Supplier and place of supply in the same State: ordinarily intra-State.
- Supplier and place of supply in different States: ordinarily inter-State.
- Supplier and place of supply in different Union Territories, or in a State and a Union Territory: ordinarily inter-State.
Those are starting points, not a substitute for the statutory rule. Goods and services have different place-of-supply provisions, and special rules can apply to transport, installation, events, immovable property, intermediaries and other arrangements. Establish the legal place of supply before selecting the tax type.
4. Apply the rate and split
Multiply the taxable value by the confirmed percentage and divide by 100. For an ordinary intra-State supply, divide the combined rate into the applicable CGST and SGST/UTGST components shown in the rate entry. For an inter-State supply, apply the integrated rate as one amount.
5. Put the result on the invoice
The tax invoice must show the taxable value, rate of tax and amount of tax. For an inter-State supply, it must also state the place of supply and the State name. Other supplier, recipient, document and supply particulars required by the invoice rules still apply.
How place of supply changes the result
Why an address shortcut can be wrong
“Same billing address” does not automatically mean CGST and SGST, and a different delivery address does not automatically prove IGST. The legally relevant place of supply may differ from a billing, shipping or payment address. Review the statutory rule for the actual goods or service and the contractual facts.
Imports, exports and SEZ transactions
Imports and supplies to or by a Special Economic Zone unit or developer have specific treatment. They should not be forced into the ordinary same-State/different-State shortcut. Export transactions and complex cross-border services likewise require the applicable place-of-supply and zero-rating rules rather than an assumed domestic split.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Goods versus services
The place-of-supply chapter is not identical for goods and services. A service can have a specific rule based on the recipient, performance location, property, event, transportation or intermediary status. If the arrangement is unusual, use the exact IGST Act provision or obtain professional advice before invoicing.
Rank #3
- Calculator
- GST calculator
- tax calculation
- GST
- calsi
Taxable value: what to include and when the simple method fails
Ordinary transaction value
The simple method works best when the parties are unrelated and price is the only consideration. In that situation, transaction value is generally the starting point under section 15 of the CGST Act. Document the agreed consideration and separately identify charges that may be statutory additions.
Incidental charges and recipient-paid amounts
Freight, packing, commission, loading, handling or similar charges can affect the base when they fall within the statutory inclusions and are charged by the supplier. A cost paid by the recipient can still be relevant if the supplier was liable for it under the arrangement. Analyse the legal provision and contract rather than applying an automatic “add every expense” rule.
Discounts
Discounts may be left out of taxable value only when the conditions in the valuation provision are met. Timing, documentation and input-tax-credit treatment can matter. A post-sale reduction without the required evidence may not reduce the taxable value.
Recommended Free Tools
Special valuation methods
Transaction value is not the answer for every supply. The valuation rules provide alternative methods for cases involving related or distinct persons, supplies through an agent, cost-based valuation and residual methods. If the parties are related, branches are involved, consideration is not wholly in money, or the normal price cannot be established, determine the prescribed method before calculating tax.
Finding the applicable GST rate
Use the current Central Board of Indirect Taxes and Customs rate table and the underlying notification for the transaction date. Read the description and every condition in the row. The table’s separate columns help you verify whether the entry is structured as a combined intra-State rate and an equivalent IGST rate, and whether compensation cess is also listed.
- Confirm the exact HSN, service classification or other category used by the notification.
- Check exemptions and conditional concessions, not only the headline percentage.
- Check whether compensation cess applies in addition to GST.
- Use the rate in force on the supply date, not an old invoice template or remembered percentage.
- When an older FAQ conflicts with a later statute or notification, give priority to the current legal text.
Worked calculations
Intra-State supply at an illustrative 18% total rate
Assume a taxable supply, a taxable value of ₹10,000 and a confirmed combined rate of 18%:
- GST = ₹10,000 × 18 ÷ 100 = ₹1,800.
- CGST at 9% = ₹10,000 × 9 ÷ 100 = ₹900.
- SGST or UTGST at 9% = ₹10,000 × 9 ÷ 100 = ₹900.
- Total invoice value before any other charges = ₹10,000 + ₹1,800 = ₹11,800.
This example assumes the supply is legally intra-State and that the 18% entry applies. It does not decide the classification, exemption status or rate of a real product or service.
Inter-State supply at an illustrative 18% integrated rate
- IGST = ₹10,000 × 18 ÷ 100 = ₹1,800.
- Total invoice value before any other charges = ₹11,800.
There is no separate CGST and SGST line for this ordinary inter-State example; the ₹1,800 is shown as IGST.
Rank #4
- GST Calculator
- Dark Mode
- Combined GST Calculator
- Save Offline
- Ease of Access
Illustrative 5% rate entry
Suppose the confirmed rate entry is 5%, structured as 2.5% CGST, 2.5% SGST/UTGST and 5% IGST, and the taxable value is ₹10,000:
| Supply type | Rate calculation | Tax | Invoice total |
|---|---|---|---|
| Intra-State | ₹10,000 × 2.5% CGST | ₹250 CGST + ₹250 SGST/UTGST = ₹500 | ₹10,500 |
| Inter-State | ₹10,000 × 5% IGST | ₹500 IGST | ₹10,500 |
The 5% row is an arithmetic illustration of a rate-table structure. It must not be generalized to other goods or services.
When the quoted price already includes GST
If a quoted amount is explicitly GST-inclusive, first separate the tax from the gross amount rather than multiplying the gross amount again. For a confirmed rate of r percent and a GST-inclusive total of G, the mathematical extraction is:
Taxable value = G × 100 ÷ (100 + r)
GST included = G − taxable value
Use this only when the entire quoted amount is the taxable consideration and no other charges, cess or valuation adjustment changes the base. Confirm the invoice terms and rate before relying on the extraction.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What the invoice should show
For calculation and auditability, the invoice should make the following visible:
- Taxable value for the supply.
- Applicable rate of tax.
- Amount of tax.
- Separate CGST and SGST/UTGST amounts for an ordinary intra-State supply.
- IGST amount for an ordinary inter-State supply.
- Place of supply with the State name for an inter-State transaction.
The invoice rules also prescribe other particulars, including supplier and recipient details, document identity and supply description. A calculator result is not a compliant invoice unless those required fields are completed.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Common mistakes and how to correct them
Assuming every supply is 18%
Problem: Applying a familiar percentage without checking the rate entry.
Fix: Verify the current classification, notification, exemption and conditions for the actual transaction date.
Best Value
- 1. GST Calculator is a handy app which allows you to calculate all 4 GST tax rates at your finger tips. It takes-in an amount (either gross or net) and allows you to add or reduce GST from given amount.
Splitting IGST into two taxes on the invoice
Problem: Showing CGST and SGST even though the supply is inter-State.
Fix: Determine place of supply first. An ordinary inter-State supply is shown as one IGST amount.
Using the customer’s address as the entire test
Problem: Treating billing or delivery geography as conclusive.
Fix: Apply the goods- or services-specific statutory place-of-supply rule.
Taxing the sticker price without checking valuation
Problem: Ignoring incidental expenses, qualifying discounts or special valuation rules.
Fix: Test the transaction-value conditions and the prescribed alternatives for related parties, agents and other non-standard cases.
Leaving place of supply off an inter-State invoice
Problem: Recording IGST but omitting the State name and place-of-supply detail.
Fix: Complete the invoice fields required for inter-State supplies before issuing the document.
Relying on an old rate table
Problem: Using a saved spreadsheet or older FAQ after a notification changes the rate or condition.
Fix: Recheck the current official table and notification whenever the transaction date, product classification or exemption changes.
A practical decision checklist
- Write down exactly what is supplied and whether it is goods or services.
- Find the current rate entry, including exemptions, concessions and compensation cess.
- Calculate the taxable value using transaction value or the applicable special valuation method.
- Establish the statutory place of supply and identify any import, export or SEZ rule.
- Calculate the tax using taxable value × rate ÷ 100.
- For intra-State supplies, allocate the combined rate to CGST and SGST/UTGST as stated in the rate entry.
- For inter-State supplies, report the integrated rate as IGST.
- Check rounding, document the calculation and include every required invoice field.
When to get transaction-specific advice
The short formula is reliable arithmetic, but it cannot resolve classification or legal interpretation by itself. Obtain qualified advice when the supply involves related or distinct persons, branches, agents, non-monetary consideration, bundled services, imports or exports, SEZ units, unusual delivery arrangements, property or event services, or a dispute over discounts and incidental charges. In these cases, the key question is not multiplication; it is which statutory rate, value and place-of-supply rule applies.
Finally, refresh the rate and place-of-supply analysis before issuing an invoice. GST legislation, notifications and rate entries can change, and an answer that was correct for an earlier transaction date may not be correct for a later one.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteQuick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
