GST calculator: add or remove GST

How to calculate GST: the two formulas

GST can be added to a price (exclusive) or already included in it (inclusive). If a price is exclusive of GST, the tax is simply GST = amount × rate ÷ 100 and the total is the amount plus GST. For ₹1,000 at 18%, GST is ₹180 and the total is ₹1,180. If a price already includes GST, you have to remove it: base = amount × 100 ÷ (100 + rate) and GST = amount − base. For ₹1,180 including 18% GST, the base is ₹1,000 and the GST is ₹180. A common mistake is to take 18% of ₹1,180 (₹212.40), which overstates the tax. The calculator above handles both directions.

CGST, SGST, UTGST and IGST explained

India's GST is split between the Centre and the states. When the supplier and the buyer's place of supply are in the same state (intra-state), the tax is divided equally into CGST (central) and SGST (state), or UTGST in union territories without a legislature. At 18%, that is 9% CGST + 9% SGST. When goods or services move between states (inter-state), or are imported, a single IGST at the full rate is charged, and the Centre later settles the state share. The total tax is the same either way; only the split on the invoice changes.

Current GST slabs (after the 2025 rate rationalisation)

From 22 September 2025 the GST Council simplified the main structure into a 5% merit rate and an 18% standard rate, with a 40% rate for a small list of luxury and "sin" goods, and nil (0%) for many essentials. Special rates continue for a few items, such as 3% for gold and jewellery and 0.25% for rough diamonds and precious stones. Most items that were earlier at 12% moved to 5%, and most at 28% moved to 18%. The 12% and 28% buttons are kept for checking older invoices or items still taxed at legacy rates. Always confirm the current rate for your HSN or SAC code on the official GST portal or with your tax adviser, because rates for specific items change through notifications.

Worked example for a small business invoice

A Delhi-based designer bills a Delhi client ₹25,000 for services at 18%. Because both are in Delhi, the invoice shows CGST 9% = ₹2,250 and SGST 9% = ₹2,250, total ₹29,500. If the client were in Mumbai, the invoice would show IGST 18% = ₹4,500 instead. The client, if GST-registered, can usually claim input tax credit for this amount, subject to the rules.

Reverse calculation for shoppers

Retail prices (MRP) in India are inclusive of all taxes. To see how much tax you paid on a ₹2,360 item taxed at 18%, choose "inclusive": the base is ₹2,000 and GST is ₹360. This is useful when comparing quotes where one seller states "+ GST" and another gives a final price.

Percentage and marks calculator

The second tool answers three everyday questions at once. Enter marks scored as X and total marks as Y to get your percentage (432 out of 500 = 86.4%). The same inputs also show X% of Y, useful for discounts and tips, and the percentage change from X to Y, useful for price rises or salary hikes.

GST on restaurant bills and online orders

Restaurant food is generally taxed at 5% without input tax credit, while restaurants in hotels with room tariffs above a set threshold may charge 18%. Food delivery platforms collect and pay this GST on behalf of restaurants. A service charge on a restaurant bill is separate from GST and, under consumer-protection guidelines in India, it is voluntary. When checking a bill, GST should be calculated on the food value, and the CGST and SGST lines should be equal.

Who must register for GST?

In general, suppliers of goods with annual turnover above ₹40 lakh and suppliers of services above ₹20 lakh (lower limits apply in some special-category states) must register, along with certain businesses such as inter-state suppliers and e-commerce sellers, regardless of turnover. Check the current thresholds on the official GST portal.

This tool gives arithmetic only and is not tax advice. Rates, exemptions and invoice rules depend on the item and your registration. For bank and card helplines, visit Credit Card Customer Care.

Frequently asked questions