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Reference
GST formulas
GST amount
Amount × GST rate ÷ 100
Total with GST
Amount + GST amount
Remove GST
Inclusive amount ÷ (1 + GST rate ÷ 100)
Example: GST on ₹1,000 at 18% is ₹180, making the total ₹1,180.
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CalcMate
Indian tax calculator
GST Calculator
Add or remove GST, split tax by invoice type, and save a clear calculation for your records.
₹
Enter the price that already includes GST.
Calculation result
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Your GST breakdown will appear here
Choose the calculation and invoice type, then select a GST rate.
Calculation history
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GST guide
Understand your GST calculation
Quick formulas, indicative rates, and plain-language answers to common GST questions.
Quick reference
GST arithmetic examples
Illustrative inputs, not product classifications or current rate advice.
| Item | GST |
|---|---|
| ₹1,000 base × 5% | ₹50 |
| ₹1,000 base × 18% | ₹180 |
| ₹1,050 inclusive at 5% | ₹50 |
| ₹1,180 inclusive at 18% | ₹180 |
Confirm classification, conditions and the effective notification using CBIC tax information. Preset buttons are calculation shortcuts.
Helpful answers
Frequently asked questions
What is GST?
GST (Goods and Services Tax) is an indirect tax charged on the supply of goods and services in India. It replaced several central and state indirect taxes with a unified tax system.
How do I calculate GST?
To add GST, multiply the base amount by the GST rate and divide by 100. Add that GST amount to the base amount to get the final price.
How do I remove GST from an inclusive price?
Divide the GST-inclusive total by 1 plus the GST rate expressed as a decimal. For example, divide an 18% GST-inclusive price by 1.18 to find its base amount.
What is the difference between IGST and CGST?
CGST is the central share of tax on an intra-state sale and is usually charged with SGST. IGST applies to inter-state supplies and is collected as a single tax.
What is reverse GST?
Reverse GST calculation means extracting the original base price and tax amount from a total that already includes GST. In this calculator, use the Remove GST option.
Practical guidance
Use the GST Calculator with confidence
Add GST to a base price or extract it from an inclusive total. See tax, net price, and equal CGST/SGST amounts with a worked example.
Worked example
Enter ₹1,000, select 18% and GST Exclusive: net amount ₹1,000, GST ₹180, total ₹1,180. The same ₹1,180 in GST Inclusive mode gives ₹1,000 net and ₹180 GST. Each equal CGST/SGST component is ₹90.
Assumptions and limits
Amounts are rounded for display, with paise shown in detailed outputs. Rates are user selections, not a classification lookup. The calculation excludes cess, input tax credit, place-of-supply decisions and invoice-level rounding rules.
How to read the result
The GST amount is the difference between the net and inclusive prices. The equal split illustrates CGST plus SGST; it does not determine whether your supply instead attracts IGST.
Inputs and units
Enter the price in rupees and the total GST percentage. Select exclusive when the price is before tax, or inclusive when it already contains tax.
Formula and variables
Add: tax = base × rate / 100; total = base + tax. Remove: base = total / (1 + rate / 100); tax = total − base.
Comparisons and common mistakes
Use Percentage for a generic percentage calculation, Sales Tax for another jurisdiction, and Invoice to combine line items. Removing 18% GST requires division by 1.18, not subtracting 18% of the inclusive price.
Does choosing a rate establish the correct GST for my product?
No. Confirm the HSN/SAC classification, conditions and effective notification using CBIC. Presets and the 18% example are arithmetic inputs, not current product-rate advice.
Guide checked
Read our calculation methodology Guide checked against the web calculator by an automated coding assistant. Independent professional review is not recorded.
Substantive guide update: .