IGST Calculator
IGST Calculator: free, instant and private. Use Add GST when you know the pre-tax price, and Remove GST when the bill already includes tax — the two directions give different answers, which is the most common GST arithmetic mistake.
How the IGST Calculator works
The IGST Calculator takes Amount, GST rate (%), Mode and returns the answer instantly — no button to hunt for, no page reload. Use Add GST when you know the pre-tax price, and Remove GST when the bill already includes tax — the two directions give different answers, which is the most common GST arithmetic mistake.
Enter your own numbers to replace the example values; the result panel updates as you type. Everything runs in this single page, so nothing you enter leaves your device.
Formula used
GST = amount × rate ÷ 100 | Base = total ÷ (1 + rate ÷ 100)
| Symbol | Meaning |
|---|---|
| amount | the figure you enter |
| rate | GST slab — 5%, 12%, 18% or 28% in India |
Use Add GST when you know the pre-tax price, and Remove GST when the bill already includes tax — the two directions give different answers, which is the most common GST arithmetic mistake.
Inputs used: Amount, GST rate (%), Mode.
Worked example
Take the default example — amount of 10000, gst rate (%) of 18, mode set to Add GST:
- Total (incl. GST): 11,800
- GST amount: 1,800
- Base amount: 10,000
Frequently asked questions
- What formula does the IGST Calculator use?
- It uses GST = amount × rate ÷ 100 | Base = total ÷ (1 + rate ÷ 100), where amount is the the figure you enter; rate is the GST slab — 5%, 12%, 18% or 28% in India.
- Is the IGST Calculator free?
- Yes. There is no signup, no usage limit and no watermark — the calculator runs entirely in your browser.
- How do I read the result?
- Use Add GST when you know the pre-tax price, and Remove GST when the bill already includes tax — the two directions give different answers, which is the most common GST arithmetic mistake.
- Does the IGST Calculator store or send my data?
- No. Every calculation happens locally in the page, so the numbers you type are never uploaded or logged.
- Does it work on a phone and offline?
- Yes — the page is a single lightweight file that adapts to any screen size. Once it has loaded it keeps working without a network connection.