Free GST Bill Calculator — CGST, SGST, IGST Instant Calculation

GST Calculator

Amount (Before GST) — ₹

GST Rate

Seller State/UT

Buyer State/UT

Taxable Amount ₹1,000

CGST + SGST (Intra-state) 9% + 9%

CGST ₹90

SGST ₹90

Total Amount ₹1,180

Intra-state transaction: CGST (Central) + SGST (State) equal halves

How it works

Same state: CGST + SGST (rate divided equally). Different state: IGST (full rate). GSTBill automatically does this for every invoice.

How to Use GST Calculator

Simple 3-Step Process

Enter Amount: Enter the pre-tax amount you want to calculate GST on.
Select GST Rate: Choose the applicable rate — 0%, 5%, 12%, 18%, or 28%.
Choose States: Select the seller and buyer states. The calculator auto-determines CGST+SGST (intra-state) or IGST (inter-state).

Result: Total amount with exact tax breakup — instantly.

CGST vs SGST vs IGST — What's the Difference?

Same State (Intra-State) → CGST + SGST

At 18% GST: CGST 9% + SGST 9% = 18% total. Both components are always equal.

Different State (Inter-State) → IGST

At 18% GST: IGST 18% (single tax, full rate). The seller deposits IGST to the central government.

0% GST → No Tax

Exempt goods (books, medicines, etc.) — no CGST, no SGST, no IGST.

GST Rates Explained

0% - Exempt goods: books, newspapers, medicines (no additive), basic food.

5% - Essential items: biscuits, other food, coal, seeds, edible oil.

12% - Mid-range goods: cosmetics, steel, bricks, cement, paper.

18% - Standard rate: clothing, furniture, electronics, most services.

28% - Luxury items: high-end cars, tobacco, aerated drinks, air conditioners.

All 38 Indian States & UTs Supported

Andaman & Nicobar, Andhra Pradesh, Arunachal Pradesh, Assam, Bihar, Chhattisgarh, Chandigarh, Delhi, Goa, Gujarat, Haryana, Himachal Pradesh, Jammu & Kashmir, Jharkhand, Karnataka, Kerala, Ladakh, Lakshadweep, Madhya Pradesh, Maharashtra, Manipur, Meghalaya, Mizoram, Nagaland, Odisha, Puducherry, Punjab, Rajasthan, Sikkim, Tamil Nadu, Telangana, Tripura, Uttar Pradesh, Uttarakhand, West Bengal, Daman & Diu, Dadra & Nagar Haveli.

Each state has a unique GSTIN code (first 2 digits). The calculator automatically detects the state from the code.

Why Manual Calculation is Risky

❌ Intra-state/inter-state confusion: Applying the wrong tax type can trigger notices from GST officers.
❌ Rounding errors: 18% of ₹1,000 = ₹180, but writing ₹181 causes an invoice mismatch.
❌ Rate mistakes: 5% vs 12% confusion — an expensive error.
✓ GSTBill automatic: Everything is auto-calculated and verified.

Auto-calculate on Every Invoice — Try GSTBill

A manual calculator is great for learning. For real invoicing, GSTBill.app handles everything automatically:

✓ Enter your GSTIN — CGST/SGST/IGST determined automatically
✓ Enter buyer GSTIN — state code auto-detected
✓ Add items — tax calculated instantly
✓ Professional PDF invoice — GST Rule 46 compliant
✓ Delivered via WhatsApp — 60 seconds total

Stop Manual Calculation — Use GSTBill

Manual calculator helps you learn. GSTBill auto-calculates every invoice. 30 free bills/month.

Start with GSTBill Web Generator

GST Calculator — FAQ

How does the GST calculator work? +

Enter the pre-GST amount and select the applicable GST rate (0%, 5%, 12%, 18%, or 28%). The calculator automatically determines CGST and SGST for same-state transactions or IGST for inter-state transactions based on seller and buyer state codes.

What is the difference between CGST and SGST? +

CGST (Central GST) goes to the central government, while SGST (State GST) goes to the state government. For same-state sales, the total GST rate is divided equally between them. For example, at 18% rate: CGST 9% and SGST 9%.

What happens when a transaction involves mixed GST rates? +

When an invoice has items with different GST rates, calculate tax separately for each rate. Sum the CGST portions, sum the SGST portions, then add to the taxable amount to get the grand total. GSTBill automatically handles this complexity.

Is GST calculated before or after discount? +

GST is calculated on the amount after any trade discount is applied. However, cash discounts offered at time of supply are excluded. For example: invoice amount ₹1000, trade discount ₹100, then GST applies to ₹900.

What is IGST and when is it applicable? +

IGST (Integrated GST) applies to inter-state transactions where seller and buyer are in different states. The full GST rate is collected as IGST instead of being split into CGST and SGST.

How are GST amounts rounded in invoices? +

GST amounts are rounded to the nearest rupee per line item. If the tax amount ends in .50 or more, round up; less than .50, round down. Total invoice rounding follows GST rules for accuracy.

Is manual GST calculation accurate for compliance? +

Manual calculation can be error-prone due to state confusion, rounding mistakes, or rate mismatches. For learning, it works well. For real invoices, automated tools like GSTBill ensure zero errors and GST Rule 46 compliance.