How to use the GST calculator
- 1Choose Add GST if your price excludes tax, or Remove GST if it already includes tax.
- 2Type the amount, then pick a rate button (5%, 18%, 40%, 3% or 0.25%) or type any rate in GST or VAT rate.
- 3Under Type of supply (India), choose Within a state for CGST + SGST or Between states for IGST.
- 4Read the net amount, tax and total, with the formula underneath. Press Copy result to copy the line.
Adding and removing 18% GST
Add GST: net price 1,000 at 18%, within a state Remove GST: total 1,180 at 18%
Add: GST 180.00 (CGST 90.00 + SGST 90.00), total 1,180.00 Remove: net price 1,000.00, GST 180.00
Removing GST divides by 1.18. Taking 18% off 1,180 would give 967.60, which is wrong: the tax was 18% of the net price, not of the total.
Adding GST to a price
When a price is quoted before tax (exclusive), multiply it by the rate to get the tax and add it on:
- GST = Net price × Rate ÷ 100
- Total = Net price + GST, or Net price × (1 + Rate ÷ 100)
At 18%, a net price of 2,500 carries 450 of GST and a total of 2,950. Businesses registered for GST quote and record the net price, the rate and each tax line separately on a tax invoice.
Removing GST from an inclusive price
Shop prices (MRP in India) and most consumer quotes already include GST. To find the price before tax, divide by 1 plus the rate:
- Net price = Total × 100 ÷ (100 + Rate)
- GST = Total − Net price
For a total of 1,050 at 5%: 1,050 × 100 ÷ 105 = 1,000, so the GST is 50. A common mistake is to take the rate off the total (1,050 − 5% = 997.50); that understates the net price because the tax was calculated on the smaller, pre-tax amount.
CGST, SGST and IGST
The rate is the same whichever way it's split; only who collects it changes.
- Intra-state supply (seller and place of supply in the same state): the tax is split equally into CGST (central) and SGST (state). In a union territory without a legislature, UTGST replaces SGST. 18% becomes 9% + 9%.
- Inter-state supply (different states), imports, and supplies to SEZ units: the full rate is charged as IGST. 18% stays 18%.
The place of supply rules in the IGST Act decide which applies, so check them for services, online sales and goods shipped to a third party.
Current GST rate slabs
From 22 September 2025, after the 56th GST Council meeting, the 12% and 28% slabs were removed and most items moved to 5% or 18%. Rates checked on 5 October 2026:
| Rate | Examples |
|---|---|
| Nil | Many unprocessed foods, UHT milk, paneer; individual life and health insurance is exempt |
| 5% | Many daily-use goods, such as soap, hair oil and toothpaste |
| 18% | The standard rate for most goods and services, including small cars, air conditioners and televisions |
| 40% | Luxury and "sin" goods: aerated drinks, large cars and motorcycles over 350 cc; tobacco and pan masala from 1 February 2026 |
| 3% | Gold, silver and jewellery |
| 0.25% | Rough diamonds |
Rates apply to an item's HSN (goods) or SAC (services) code, so look up your code in the official rate notifications rather than relying on a category name.
GST formulas
| Task | Formula | 18% example |
|---|---|---|
| Add GST | Total = Net × (1 + r ÷ 100) | 1,000 → 1,180 |
| GST on a net price | GST = Net × r ÷ 100 | 1,000 → 180 |
| Remove GST | Net = Total × 100 ÷ (100 + r) | 1,180 → 1,000 |
| GST inside a total | GST = Total × r ÷ (100 + r) | 1,180 → 180 |
| CGST and SGST | each = GST ÷ 2 | 90 + 90 |
The same formulas work for VAT and other sales taxes: type the rate (for example 20% UK VAT) and ignore the supply-type split.
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