GST Calculator India
Compute GST at any standard slab — add it to a base price or extract it from an inclusive amount. CGST, SGST, and IGST splits included automatically.
About this tool
A GST calculator built around the four Indian GST slabs (5%, 12%, 18%, 28%) and the dual-tax structure (CGST + SGST for intra-state, IGST for inter-state). Add GST to a net amount, remove GST from an inclusive amount, or compute the tax split for any transaction in seconds.
How to use it
Quick steps to get the most out of this utility.
- 1
Pick the GST slab
5% for essentials, 12% for processed food and certain services, 18% for most B2B services and consumer goods, 28% for luxury and sin items.
- 2
Choose direction
"Add GST" — start from net price, get gross. "Remove GST" — start from gross price (e.g., MRP), extract the tax.
- 3
Set intra-state or inter-state
Intra-state splits into CGST + SGST (equal halves). Inter-state is IGST (full slab in one line).
- 4
Enter amount
The net or gross figure, depending on direction chosen.
- 5
Read & export
See base, tax, total, and the CGST/SGST or IGST split. Download for invoice records or input vouchers.
The four moves every business should know
GST math comes up dozens of times a week for any business owner, freelancer, or accountant. Four core operations cover 95% of real-world cases:
- Add GST to a quote: net × (1 + slab) = total invoice amount.
- Extract GST from an MRP / inclusive price: total × slab / (100 + slab) = tax portion.
- Split into CGST + SGST: tax ÷ 2 each, for intra-state invoices.
- Reverse-charge for unregistered suppliers: buyer pays GST on the supplier's behalf and claims it as input credit.
A worked example — 18% GST on a ₹50,000 service
- Base service price: ₹50,000
- GST (18%): ₹9,000
- Total invoice: ₹59,000
- Intra-state split: CGST ₹4,500 + SGST ₹4,500
- Inter-state: IGST ₹9,000
Common GST mistakes to avoid
- Using "18% of total" instead of "18 / 118 of total" to extract GST from inclusive amounts — overstates the tax by ~3%.
- Charging IGST on intra-state transactions (should be CGST + SGST) or vice versa — buyers cannot reclaim mismatched tax.
- Forgetting the cess on 28%-slab luxury items — leads to short-payment penalties.
- Not raising a GST invoice for B2B sales above the threshold — buyers lose ITC and you lose the customer.
Frequently asked questions
What are the GST slabs in India?+
Five main slabs — 0% (exempt), 5%, 12%, 18%, and 28%. Plus a "cess" on certain luxury and sin goods on top of 28%. Most consumer services and goods fall in the 18% slab. Essentials like unbranded food grains, books, and most healthcare are at 0%. Luxury cars, tobacco, and aerated drinks sit at 28% + cess. The slab structure occasionally shifts at GST Council meetings — always verify the current rate on the GST portal for big-ticket items.
What is the difference between CGST, SGST, and IGST?+
For transactions within the same state, GST is split into CGST (Central) and SGST (State) — equal halves of the slab rate. So on an 18% intra-state invoice: 9% CGST + 9% SGST. For inter-state transactions, the full rate goes to IGST (Integrated GST), collected by the Centre and later shared with the destination state. The amount of tax is identical either way; only the bookkeeping differs.
How do I extract GST from an inclusive amount?+
If a price is "inclusive of 18% GST," the GST portion is amount × 18 / 118, and the base is amount × 100 / 118. Example: a ₹11,800 inclusive invoice has ₹1,800 GST and ₹10,000 base. For other slabs, replace 18 with 5, 12, or 28 in the same formula. The calculator does this instantly — just pick "remove GST" and enter the inclusive amount.
When should I charge GST?+
If your business is GST-registered (mandatory above ₹40 lakh turnover for goods, ₹20 lakh for services, lower in some states), you must charge GST on every taxable supply. Exempt goods/services or zero-rated exports may not require charging, but registration and filing are still required. If you are below the threshold, GST registration is optional — but voluntary registration lets you claim input tax credit, which can be valuable for B2B businesses.
Is GST different for goods and services?+
The slab structure is the same, but the slab a specific item falls into is defined by its HSN (Harmonized System Nomenclature) code for goods and SAC (Service Accounting Code) for services. Two products that look similar can fall in different slabs based on their classification. For invoicing, always verify the HSN/SAC and corresponding rate from the official rate notification — getting it wrong creates compliance issues at GST audit.
Keep exploring
More utilities and reading from Toolisk.