GST Calculator (India) — Simple inclusive/exclusive GST math with optional split view. Enter an amount, pick a GST rate (5%, 12%, 18%, 28%), and choose whether your amount is Exclusive (before GST) or Inclusive (tax already included). You’ll see the base amount, GST amount, and Total, plus an optional breakup into CGST + SGST (intra‑state) or IGST (inter‑state).
How to use this calculator
- Enter Amount — If your price already includes GST (MRP), choose Inclusive. If your price is before GST (tax to be added), choose Exclusive.
- Choose GST % — commonly 5%, 12%, 18%, 28% (use the slab for your item).
- Pick Tax mode — Exclusive or Inclusive.
- (Optional) Rounding — round results to the nearest ₹1 for clean invoice totals.
- (Optional) Split — select Intra‑state (CGST + SGST) or Inter‑state (IGST) to see the breakup.
- Read the outputs: Actual/Base Amount, GST Amount, and Total Amount.
Formulas
Let A = entered amount; r = GST rate (decimal). Exclusive → amount is before GST. Inclusive → amount already includes GST.
Exclusive mode: Base = A; GST = Base × r; Total = Base + GST.
Inclusive mode: Base = A / (1 + r); GST = A − Base; Total = A.
Split: Intra‑state → CGST = GST / 2, SGST = GST / 2. Inter‑state → IGST = GST.
Inputs & outputs (at a glance)
Inputs
- Amount
- GST % (5, 12, 18, 28)
- Tax mode: Exclusive or Inclusive
- (Optional) Rounding to nearest ₹1
- (Optional) Split: Intra‑state (CGST + SGST) or Inter‑state (IGST)
Outputs
- Actual/Base Amount (taxable value)
- GST Amount
- Total Amount (payable/collectible)
- Split view: CGST + SGST or IGST (informational)
Worked example
A) Exclusive
- Amount: ₹10,000 (before GST)
- GST: 18%
- GST = 10000 × 0.18 = ₹1,800
- Total = 10000 + 1800 = ₹11,800
- Split (intra‑state): CGST = ₹900, SGST = ₹900
B) Inclusive
- Amount (MRP): ₹11,800 (includes GST @ 18%)
- Base = 11800 / 1.18 = ₹10,000
- GST = 11800 − 10000 = ₹1,800
- Split (inter‑state): IGST = ₹1,800
Tips & edge cases (India)
- Inclusive vs Exclusive: MRP labels are typically inclusive; wholesale/base quotes are often exclusive.
- Split selection: Use CGST + SGST for intra‑state supply; use IGST for inter‑state supply.
- Rounding: Many businesses round invoice totals to the nearest rupee; ensure line items still tie out.
- Rates differ: Confirm HSN/SAC classification for the correct slab.
- Cess & special cases: Compensation cess and special schemes are not covered—add them separately if applicable.
- ITC (Input Tax Credit): This calculator shows output tax math only; ITC is handled in returns.
Glossary
- GST (Goods and Services Tax): Indirect tax on supplies in India.
- Base/Taxable value: Amount before GST.
- CGST/SGST: Split of GST for intra‑state supplies—half to Centre, half to State.
- IGST: GST for inter‑state supplies.
- Inclusive price: Price including GST.
- Exclusive price: Price excluding GST (GST is added).
Changelog
- v1.0 — Initial release with inclusive/exclusive modes, rounding, and CGST/SGST/IGST split view.
FAQs
➜ How do I know which split to use—CGST/SGST or IGST?
If supplier and customer are in the same state use CGST + SGST. Different states/UTs use IGST.
➜ Does this tool handle compensation cess?
No. If your item attracts cess, add it separately on the invoice.
➜ What GST rate should I select?
Rates vary by HSN/SAC. Common slabs are 5%, 12%, 18%, and 28%—confirm your classification.
➜ Why are inclusive/exclusive results slightly off after rounding?
Rounding adjusts figures to the nearest ₹1 for invoice‑friendly totals. Disable rounding for exact decimals.
➜ Can I use this for return filing or ITC?
Use this for quick invoice math only. ITC and return calculations depend on your books and GST portal rules.
➜ Is freight/packing included in the base amount?
If freight/packing is part of the taxable value for your invoice, add it into the Amount before calculating.
