Reverse GST Calculator
Remove GST from an inclusive amount and find taxable value, GST amount, CGST/SGST or IGST split.
Remove GST from MRP
Use reverse GST when the sticker price or quoted total already includes tax.
Check tax split
Choose intra-state for equal CGST/SGST split, or inter-state for IGST.
Verify rate before use
GST rate depends on product/service classification and notifications.
Reverse GST formula
The GST amount is the inclusive amount minus the base amount. At 0% GST, the base amount equals the total.
Reverse GST examples for 5%, 12%, 18% and 28%
| Inclusive Amount | GST Rate | Taxable Value | GST Included | Formula |
|---|---|---|---|---|
| ₹1,180 | 18% | ₹1,000 | ₹180 | 1180 × 100 ÷ 118 |
| ₹11,800 | 18% | ₹10,000 | ₹1,800 | 11800 × 100 ÷ 118 |
| ₹1,050 | 5% | ₹1,000 | ₹50 | 1050 × 100 ÷ 105 |
| ₹1,120 | 12% | ₹1,000 | ₹120 | 1120 × 100 ÷ 112 |
| ₹1,280 | 28% | ₹1,000 | ₹280 | 1280 × 100 ÷ 128 |
These are arithmetic examples only. Verify the applicable GST rate before invoicing.
When to use this reverse GST calculator
Remove GST from MRP
Back-calculate the taxable value when the total price already includes GST.
Check invoice breakdown
Review whether the taxable value and GST shown on a bill look reasonable.
Find taxable value from total
Convert an inclusive quotation or total into a base amount.
Split CGST/SGST or IGST
See the intra-state split or inter-state IGST amount from the same GST total.
Inclusive vs exclusive GST
Inclusive GST means tax is already inside the total amount. Exclusive GST means GST is added on top of the taxable value. This page is for inclusive GST back-calculation.
Common mistakes
- Do not subtract 18% directly from the inclusive total. GST is calculated on the base amount.
- Inclusive GST means GST is already inside the amount.
- For intra-state supplies, split GST into CGST and SGST.
- Verify rate using HSN/SAC and relevant GST references before invoicing or filing.
FAQs
What is a reverse GST calculator?
A reverse GST calculator removes GST from a GST-inclusive amount and shows the taxable value and GST amount already included in the total.
How do I remove GST from a total amount?
Use the formula: taxable value = inclusive amount x 100 / (100 + GST rate). GST amount is the inclusive amount minus taxable value.
How do I calculate base amount from GST-inclusive price?
Divide the inclusive price by 1 plus the GST rate. For 18%, divide by 1.18, or use inclusive amount x 100 / 118.
How is CGST/SGST split calculated?
For intra-state supplies, the GST amount is split equally into CGST and SGST. For example, GST of Rs 180 becomes CGST Rs 90 and SGST Rs 90.
Is reverse GST the same as inclusive GST?
Reverse GST is the back-calculation from an inclusive GST amount. It helps find the exclusive taxable value and tax already included.
Can I use this for invoices?
Use it as an estimate and calculation helper. Before invoicing or filing, verify the GST rate, HSN/SAC classification, place of supply and invoice treatment.
What if GST rate is 0%?
At 0% GST, the taxable/base amount equals the inclusive amount and GST included is zero.
Why not subtract 18% directly?
Because 18% is applied on the base amount, not the inclusive total. For Rs 1,180 at 18%, the base is Rs 1,000, not Rs 967.60.
Safety & source note
This calculator is for estimation and arithmetic checks. GST rate, place of supply, HSN/SAC classification and invoice treatment should be verified before invoicing, filing or making tax decisions.
- It does not verify GST rate.
- It does not verify HSN/SAC classification.
- It does not create a valid tax invoice.
- It does not file GST returns.