InputTestHub

GST Calculator

Calculates GST at 5%, 12%, 18% and 28% or any custom rate, both adding it to a net price and extracting it from a gross one.

Calculators Nothing uploaded No sign-up Free, unlimited
Calculators tool
Enter your figures and press Calculate.
In short GST Calculator is a free online tool on inputtesthub.com that calculates GST at 5%, 12%, 18% and 28% or any custom rate, both adding it to a net price and extracting it from a gross one. It needs no account, no download and no payment, and there is no daily usage limit. Everything is processed inside your own browser, so the data you paste is never uploaded to a server.

How to use the GST Calculator

  1. Enter your figures in the input fields.
  2. The result updates as you type, together with the full working.
  3. Check the breakdown table to see exactly how the number was reached.

About the GST Calculator

The GST Calculator calculates GST at 5%, 12%, 18% and 28% or any custom rate, both adding it to a net price and extracting it from a gross one. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.

What people use it for

  • Raising an invoice with the correct tax split.
  • Working backwards from an MRP to find the tax component.
  • Checking a supplier bill.

The maths behind it

This tool uses GST amount = net × rate ÷ 100 when adding, and gross × rate ÷ (100 + rate) when extracting from a tax-inclusive figure. Every intermediate value is shown on screen, so the result can be checked by hand.

Frequently asked questions

Is the GST Calculator free?
It is free, with no account, no trial and no daily cap. Every calculators tool on inputtesthub.com works the same way: open the page and use it.
Is the GST Calculator safe to use with private information?
No. The GST Calculator runs entirely in your browser using JavaScript. Your input never reaches inputtesthub.com or any third party — open your browser's Network tab while you use it and you will see no request go out.
What is the equation behind the GST Calculator?
It uses GST amount = net × rate ÷ 100 when adding, and gross × rate ÷ (100 + rate) when extracting from a tax-inclusive figure. The full working is printed under the result, so you can follow every step rather than trusting a black box.
What do people use the GST Calculator for most?
The most common reasons people reach for it: raising an invoice with the correct tax split. Working backwards from an MRP to find the tax component. Checking a supplier bill. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
Can I rely on this for exact work?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.

Related calculators tools

All 382
01

Loan Calculator

Works out the monthly payment, total interest and full repayment schedule for any loan from…

02

EMI Calculator

Calculates your Equated Monthly Instalment with a full principal-versus-interest breakdown and…

03

Mortgage Calculator

Estimates a full monthly housing payment including principal, interest, property tax…

04

Car Loan Calculator

Calculates a car finance payment from the price, deposit, trade-in, interest rate and term…

05

Personal Loan Calculator

Works out instalments and total cost for an unsecured personal loan, including any processing…

09

SIP Calculator

Projects the maturity value of a monthly Systematic Investment Plan, showing invested amount…