GST calculator guide: add or remove tax with confidence
GST calculations start with one important question: is the amount you entered before tax or already inclusive of tax? This free GST calculator handles both directions, shows the taxable value, and separates CGST and SGST from IGST. The rate list follows GST 2.0, effective 22 September 2025, which retired the 12% and 28% slabs and folded compensation cess into the headline rate — so what remains is 0%, 3% on gold and jewellery, 5%, 18% and the 40% de-merit rate on tobacco, aerated drinks and luxury goods. Use it to check a price, prepare a quotation, verify an invoice total or compare the final cost of a purchase before you commit to it.
Frequently asked questions
How does the GST calculator work?
Enter the amount, select the applicable GST rate (0%, 3%, 5%, 18% or 40%), and choose whether the amount is GST-exclusive (add GST) or GST-inclusive (extract GST). The tool instantly calculates the base value, CGST/SGST or IGST, and final total.
What is the difference between CGST, SGST, and IGST?
Intra-state sales split GST equally between CGST (Central GST) and SGST (State GST). Inter-state sales charge the entire tax as IGST (Integrated GST).
Can I use this for both products and services?
Yes, the calculator works for both goods and services under Indian GST law.
Which GST slab rates are available after GST 2.0?
Since 22 September 2025 the old 12% and 28% slabs are gone, and the compensation cess has been folded into the headline rate. This calculator offers the rates that remain: 0% (exempt and nil-rated goods such as fresh produce, specified life-saving drugs and individual health and life insurance), 5% (the merit rate covering packaged food, medicines, tractor inputs and hotel rooms between ₹1,000 and ₹7,500), 18% (the standard rate for mobiles, laptops, cement, white goods, IT and financial services, and restaurants), and 40% (the de-merit rate for tobacco, pan masala, aerated drinks, cars over 1,200cc, motorcycles over 350cc, yachts and online gaming). Special rates outside the rationalisation still apply — 3% on gold, silver and jewellery, and 0.25% on rough diamonds. Certain supplies are value-conditional rather than a single slab: apparel is 5% up to ₹2,500 per piece and 18% above it, and hotel rooms are nil below ₹1,000, 5% from ₹1,000 to ₹7,500 without input tax credit, and 18% above ₹7,500. An invoice still quoting 12% or 28% after 22 September 2025 is incorrect and can attract scrutiny under Section 122 of the CGST Act, so those slabs are deliberately not offered here.
When should I use GST-exclusive vs GST-inclusive calculation?
Use exclusive (add GST) when you know the base/taxable price and want the final bill amount. Use inclusive (extract GST) when the quoted price already includes tax and you need to split the base value and GST for your invoice.
Is GST charged on the discount or on the list price?
GST is generally calculated on the taxable value of the supply. If a trade or volume discount changes that value before invoicing, make sure the discount and tax treatment are reflected consistently in the final GST invoice. Post-sale discounts and other adjustments can have different treatment, so confirm the applicable rule.
Still unsure about a rate or your situation?
Every business case is different. If you are unsure which rate applies to your goods or services, email rautprajwal36@gmail.com and we will help you figure it out.