GST Calculator

How do you add or remove GST from a price?

This free online GST calculator adds GST to a net price or removes it from a GST-inclusive price. Enter the amount, pick a rate from 5, 12, 18, 28, 3 or 0.25 percent, choose Add GST or Remove GST, and press Calculate. The tool shows the net price, the GST amount, the CGST and SGST split and the gross price.

What does the GST calculator do and why is it useful?

Goods and Services Tax is charged as a percentage of the price. Adding it is easy: multiply by the rate. Removing it is where people slip, because the tax is a share of the net price, not of the total. Taking 18 percent off a GST-inclusive bill gives the wrong answer, and the calculator avoids that error.

For any calculation, it displays four values:

• Net price: the price before GST.
• GST amount: the tax portion.
• CGST and SGST: the GST amount divided into two equal halves.
• Gross price: the price including GST.

It is handy when you prepare an invoice, check a quotation, verify a shop bill or work out what a supplier price is before tax.

How does the GST calculator work under the hood?

The tool applies two simple formulas, depending on the action you choose.

Add GST: the amount you type is treated as the net price. GST amount = net x rate / 100. Gross = net + GST amount.

Remove GST: the amount you type is treated as the gross price. Net = gross / (1 + rate / 100). GST amount = gross - net.

The CGST and SGST figures are each exactly half of the GST amount. This is how tax is split for a sale within one state: the central part and the state part are equal. For a sale between two states, the whole tax is charged as IGST instead, which equals the full GST amount shown by the tool. The calculator does not ask whether a sale is intra-state or inter-state, so read the split as the intra-state view and the total GST amount as the IGST figure.

Nothing is calculated until you press the button. Changing the amount, rate or action has no effect until you press Calculate again.

How do you use the GST calculator step by step?

1. Type the amount in the amount field.
2. Choose a GST rate from the select list: 5, 12, 18, 28, 3 or 0.25 percent.
3. Choose the action: Add GST if your amount is the price before tax, or Remove GST if it already includes tax.
4. Press the Calculate button.
5. Read the net price, GST amount, CGST, SGST and gross price.

What are some worked examples?

All figures were calculated with the formulas above.

Example 1: add 18 percent GST to 1,000

Input: amount 1000, rate 18, action Add GST. Net price: 1,000.00. GST amount: 180.00. CGST: 90.00. SGST: 90.00. Gross price: 1,180.00.

Example 2: remove 18 percent GST from 1,180

Input: amount 1180, rate 18, action Remove GST. Net price: 1,000.00. GST amount: 180.00. CGST: 90.00. SGST: 90.00. Gross price: 1,180.00. This is the reverse of Example 1 and returns the starting price.

Example 3: add 12 percent GST to 2,500

Input: 2500, 12, Add GST. Net price: 2,500.00. GST amount: 300.00. CGST: 150.00. SGST: 150.00. Gross price: 2,800.00.

Example 4: remove 28 percent GST from 12,800

Input: 12800, 28, Remove GST. Net price: 10,000.00. GST amount: 2,800.00. CGST: 1,400.00. SGST: 1,400.00. Gross price: 12,800.00.

Example 5: add 28 percent GST to 999

Input: 999, 28, Add GST. Net price: 999.00. GST amount: 279.72. CGST: 139.86. SGST: 139.86. Gross price: 1,278.72.

Example 6: the two smallest rates

Input: 50000, 3, Add GST. Net price: 50,000.00. GST amount: 1,500.00. CGST: 750.00. SGST: 750.00. Gross price: 51,500.00. With 80000 at 0.25 and Add GST, the net price is 80,000.00, the GST amount is 200.00, CGST and SGST are 100.00 each and the gross price is 80,200.00. The same method works for every option in the list, only the percentage changes.

Amount	Rate	Action	Net	GST	Gross
1,000	18%	Add	1,000.00	180.00	1,180.00
1,180	18%	Remove	1,000.00	180.00	1,180.00
2,500	12%	Add	2,500.00	300.00	2,800.00
12,800	28%	Remove	10,000.00	2,800.00	12,800.00
999	28%	Add	999.00	279.72	1,278.72
50,000	3%	Add	50,000.00	1,500.00	51,500.00

How can you check the result yourself?

A quick sanity check takes a few seconds. For Add GST, the gross price divided by the net price should equal 1 plus the rate as a decimal, so 1,180 divided by 1,000 gives 1.18 at 18 percent. For Remove GST, multiply the net price by the same factor and you should land back on the amount you typed. If the two do not agree, the usual cause is the wrong action or the wrong rate, and pressing Calculate again after correcting the field fixes it.

What tips help you get accurate GST figures?

• Decide first whether your amount includes tax. This single choice drives the whole result.
• Use Remove GST for shelf prices and final bills, and Add GST for quotes and supplier rates.
• Check the rate against your product or service. Rates can change, so check current rates before relying on a figure.
• Keep the original bill or quotation open while you work, because small differences usually come from rounding or from a wrong rate and are easy to spot side by side.
• Round only at the end. If you have several line items, calculate each one and compare the sum with your invoice total.
• Use the Discount Calculator first if a discount applies, then add GST to the discounted price, following the rule that applies to your invoice.
• For general percentage checks, the Percentage Calculator is a useful companion.

What are common mistakes?

• Subtracting the rate from the gross price. Removing 18 percent from 1,180 by taking 18 percent of 1,180 gives 212.40 and a wrong net of 967.60. The correct net is 1,000.00.
• Choosing the wrong action. Using Add GST on a price that already includes tax charges the customer twice.
• Picking the wrong rate. The select list holds fixed options, so pick the one that matches your item.
• Mixing up CGST, SGST and IGST. Inter-state sales carry IGST, which is the full GST amount, not two halves.
• Expecting live updates. Results show up only after you press Calculate.

Who uses a GST calculator?

Small shop owners use it at the counter to confirm a bill. Freelancers and consultants use it to prepare invoices. Accountants use it for quick checks while reviewing entries. Buyers use it to see how much of a price is tax. Students of commerce use it to practise the add and remove methods. When a bill also includes a gratuity, the Tip Calculator handles that separate step.

Is my data private?

Yes. The calculation runs in your browser. The amounts you enter are not uploaded and not stored, and the tool keeps no record of past calculations. Refreshing the page clears everything.

What are the limitations?

• The rate list is limited to 5, 12, 18, 28, 3 and 0.25 percent. Other rates are not available.
• Rates and rules can change, so always check the current rates.
• The tool treats every calculation as a single amount. It does not handle several items, cess or invoice formats.
• The CGST and SGST split is always half and half. For inter-state sales use the total GST amount as IGST.
• It does not decide which rate applies to your goods or service.

Frequently asked questions

What is the difference between Add GST and Remove GST?

Add GST treats your amount as the price before tax and adds the tax on top. Remove GST treats your amount as the price with tax and separates the tax out.

Which GST rates can I choose?

5, 12, 18, 28, 3 and 0.25 percent.

How is the CGST and SGST split calculated?

Each is exactly half of the total GST amount.

What is IGST?

IGST is the tax charged on a sale between two states. It equals the full GST amount, which the tool shows as the GST amount.

Why is removing GST not the same as subtracting the percentage?

The tax is a share of the net price. The net is the gross divided by 1 plus the rate, so subtracting a percentage of the gross removes too much.

Are the GST rates always current?

Rates can change. Check the current rates before using the result in a bill or filing.

Does the tool store my numbers?

No. Everything happens in your browser and nothing is uploaded or stored.

Why are results not shown while I type?

There is one Calculate button, and results are generated only when you press it.

Get the tax split right every time

Knowing whether a price is net or gross prevents most GST errors. Use the calculator for quick checks, confirm the rate for your item, and browse more free tools for everyday numbers.