GST Calculator for Different Slabs — 5%, 12%, 18%, 28% Explained
India's main GST slabs are 5%, 12%, 18%, and 28%. To add GST, multiply the base by 1.05, 1.12, 1.18, or 1.28. To pull GST out of an inclusive price, use total × rate ÷ (100 + rate) — for example, ₹11,800 at 18% is ₹1,800 tax on a ₹10,000 base, not 18% of the gross.
If you are staring at an invoice that says 12% or 28%, you need the math for that slab — not a walkthrough that assumes 18% throughout. Most people searching for a GST calculator already know the rate; they just need tax on top of a base price, and tax pulled out of a price that already includes it.
We covered the 18% case in detail in How to Calculate GST Inclusive Price. This piece does the same for all four main slabs — 5%, 12%, 18%, and 28% — with a simple worked example for each.
The product examples below are common associations — packaged food at 5%, cars at 28%, and so on. The GST Council does move items between slabs, so always check the current rate for your HSN or SAC code before you raise an invoice.
GST slab rates in India at a glance
Whatever the slab, the formulas stay the same. Only the rate changes:
Add GST: Inclusive = Base × (1 + rate/100)
Remove GST: Tax = Inclusive × rate ÷ (100 + rate)
Base = Inclusive × 100 ÷ (100 + rate)
| Slab | Add GST | Remove GST | CGST + SGST |
|---|---|---|---|
| 5% | × 1.05 | ÷ 105 | 2.5% + 2.5% |
| 12% | × 1.12 | ÷ 112 | 6% + 6% |
| 18% | × 1.18 | ÷ 118 | 9% + 9% |
| 28% | × 1.28 | ÷ 128 | 14% + 14% |
Intra-state sales split the tax equally into CGST and SGST. Cross-state sales use IGST at the same total rate.
5% GST — everyday essentials
Think packaged food staples, lower-price clothing or footwear (where notified), economy hotel rooms, and similar mass-market stuff. Exact lists change, but 5% is the "essentials" feel of the rate tree.
Say you sell something with a ₹2,000 taxable value:
GST (5%) = ₹2,000 × 5 ÷ 100 = ₹100
CGST 2.5% = ₹50
SGST 2.5% = ₹50
Inclusive = ₹2,000 × 1.05 = ₹2,100
Customer already paid ₹2,100 and you need the split back out:
GST = ₹2,100 × 5 ÷ 105 = ₹100
Base = ₹2,100 × 100 ÷ 105 = ₹2,000
A flat 5% of ₹2,100 is ₹105 — a little too high. For 5%, the reverse always divides by 105, not 100.
12% GST — the middle slab
This is where a lot of mid-range processed foods and notified consumer goods tend to land. If your invoice says 12%, you are not alone — it is a common search for a reason.
Base of ₹5,000:
GST (12%) = ₹5,000 × 12 ÷ 100 = ₹600
CGST 6% = ₹300
SGST 6% = ₹300
Inclusive = ₹5,000 × 1.12 = ₹5,600
Working backward from ₹5,600 inclusive:
GST = ₹5,600 × 12 ÷ 112 = ₹600
Base = ₹5,600 × 100 ÷ 112 = ₹5,000
No need to memorise ÷112. Open the GST Calculator, tap 12%, and switch between Add GST and Remove GST.
18% GST — the rate most invoices use
IT and consulting, many restaurants, financial services, a lot of electronics — 18% is the default people bump into most often. If you only want this slab unpacked slowly, the inclusive-price guide stays the deeper read.
Base of ₹10,000:
GST (18%) = ₹10,000 × 18 ÷ 100 = ₹1,800
CGST 9% = ₹900
SGST 9% = ₹900
Inclusive = ₹10,000 × 1.18 = ₹11,800
From ₹11,800 inclusive:
GST = ₹11,800 × 18 ÷ 118 = ₹1,800
Base = ₹11,800 × 100 ÷ 118 = ₹10,000
This is where the classic mistake shows up: 18% of ₹11,800 is ₹2,124. That number looks confident and is wrong for books, GSTR, and input tax credit.
28% GST — where the rupees get big fast
Cars, aerated drinks, tobacco-related products, plenty of high-end durables — this is the slab that hurts if you reverse it wrong. A small formula error is a large rupee error.
Same ₹10,000 base:
GST (28%) = ₹10,000 × 28 ÷ 100 = ₹2,800
CGST 14% = ₹1,400
SGST 14% = ₹1,400
Inclusive = ₹10,000 × 1.28 = ₹12,800
From ₹12,800 inclusive:
GST = ₹12,800 × 28 ÷ 128 = ₹2,800
Base = ₹12,800 × 100 ÷ 128 = ₹10,000
A flat 28% of ₹12,800 is ₹3,584 — more than ₹700 too much tax. For a 28% check, Remove GST with rate 28 applies ÷128 for you.
Same ₹10,000 base, four different bills
Same taxable value. Very different cash at the counter:
| Rate | GST | CGST / SGST | Inclusive |
|---|---|---|---|
| 5% | ₹500 | ₹250 each | ₹10,500 |
| 12% | ₹1,200 | ₹600 each | ₹11,200 |
| 18% | ₹1,800 | ₹900 each | ₹11,800 |
| 28% | ₹2,800 | ₹1,400 each | ₹12,800 |
That gap is why picking (or checking) the slab on an invoice is not a cosmetic detail.
Add GST or Remove GST?
- Add GST when you know the taxable value and need the tax plus what the customer pays — the usual path when you raise a tax invoice from a quoted base.
- Remove GST when the sticker or receipt already includes tax and you need the split for books, GSTR, or ITC. Use
rate ÷ (100 + rate). Never take a flat percent of the gross.
Skip the hand arithmetic
You do not need four spreadsheets. The free GST Calculator at TinyToolStudio already has buttons for 0%, 5%, 12%, 18%, and 28% (plus a custom rate):
- Switch between Add GST and Remove GST
- Tap the slab (or type it)
- Read base, CGST, SGST, total GST, and final amount
It runs in your browser, needs no signup, and the figures never leave your device — handy whether you are checking a 5% line item or a 28% car invoice before you file.
The short version
The four everyday GST slabs are 5%, 12%, 18%, and 28%. Add tax with ×1.05 / ×1.12 / ×1.18 / ×1.28. Pull tax out with ÷105 / ÷112 / ÷118 / ÷128. Confirm the current rate for your item, then use the GST Calculator if you would rather not do the arithmetic by hand.
Try it free → www.tinytoolstudio.com/tools/gst-calculator
Frequently Asked Questions
- What are the main GST slab rates in India?
- The four rates people use most are 5%, 12%, 18%, and 28%. Some goods and services are nil-rated or exempt. Which item sits in which slab can change when the GST Council updates the tariff, so confirm the rate for your HSN or SAC code before you invoice.
- How do I use a GST calculator for 5% or 12%?
- Choose Add GST or Remove GST, enter the amount, and set the rate to 5 or 12. Add GST multiplies the base by 1.05 or 1.12. Remove GST uses total × rate ÷ (100 + rate) — divide by 105 for 5%, and by 112 for 12%.
- How is 28% GST calculated on an inclusive price?
- GST = inclusive total × 28 ÷ 128, and base = inclusive total × 100 ÷ 128. So ₹12,800 inclusive of 28% GST is ₹10,000 base plus ₹2,800 tax. Taking a flat 28% of ₹12,800 gives the wrong, higher number.
- Is GST split into CGST and SGST at every slab?
- For sales inside the same state, yes — total GST is split equally into CGST and SGST. At 18% that is 9% + 9%; at 28% it is 14% + 14%; at 5% it is 2.5% + 2.5%. Sales across states use IGST at the same total rate instead.
- Which products usually attract 5% vs 28% GST?
- 5% often covers everyday essentials — certain packaged foods, notified lower-price clothing or footwear, economy hotel stays. 28% is where motor vehicles, aerated drinks, and many high-end durables tend to sit. Always double-check the current rate for your HSN code, because items do move between slabs.