Demystifying GST Calculations: A Comprehensive Guide For Sales And Purchases

Home » Blogs » Demystifying GST Calculations: A Comprehensive Guide For Sales And Purchases

Published Date:  02-02-2024   Author:   amitha-shet
captainbiz demystifying gst calculations a comprehensive guide for sales and purchases

Introduction to goods and services tax (GST)

GST is also claimed to be a form of indirect tax that is to be paid on the value addition of different stages of the goods. These stages can be production, delivery of the goods, logistics, and consumption of these goods and services. 

Any customer who purchases the goods and services is supposed to bear the tax levied upon him. Different businesses are supposed to collect taxes from different customers and remit them to the government. 

There are certain features upon which this GST system is based. These are: 

  1. One nation, one tax: What GST rules believe is to carry on a unified tax system. It helps different businesses with compliance with the tax. It also promotes efficiency in the overall taxation system. 
  2. Multiple-stage tax: One by one, at every stage of value addition, GST is applied to the goods. This way, it will help cope with paying taxes twice. It also makes sure no one bears the tax burden. 
  3. Destination-based tax: Any tax that is levied on the goods and services has to be paid at the final stage of the consumption of the goods. This helps in ensuring revenue. It also promotes a competitive environment among different states. 
  4. Multiple tax rates: There are various categories of goods and services, and the GST that is levied on these goods is different as per their categories and uses. 

Benefits of GST

The following are the benefits of GST: 

  1. It works well to promote transparency and efficiency in the organization 
  2. It boosts economic growth. 
  3. Helps in improving tax compliance. 


  1. Sometimes it is crucial to find out the exact tax rate and follow the GST rules. 
  2. Certain sectors get disturbed while adapting to the latest GST regime. 

GST calculations for sale

When you come across the calculation of GST, there are some of the terms you would go through. These are: 

start free trial of gst billing software

  1. CGST: It is imposed on goods and services by the central government. 
  2. HSN code: This code categorizes goods and services for tax. 
  3. IGST: This tax takes place in an interstate transaction. 
  4. SGST: This category of tax is applied by the state exactly where the sale has taken place. 
  5. Net price: It’s considered the price that comes before adding the GST to it. 

To calculate GST using the GST calculation formula, it’s important to understand different tax rates as per the laws of different countries. The category of taxation lies within 28% as the highest GST rate levied on any goods and services, then 18%, 12%, and lastly 5% as the lowest GST rate. 

GST doesn’t have to be applied to every product. Some products are exempt from paying any GST. 

There are different situations in which the GST rates and categories can be calculated. The first is when the sale is made within the state. The formula will be: 

For the CGST: 

Net price x (CGST Rate/100) = CGST

Net Price x (SGST/UTGST Rate/100) = SGST/UTGST

Net Price + CGST + SGST/UTGST = Gross Price

start free trial of gst billing software

When the sale or transaction is interstate, the following formula will be used: 

Net Price x (IGST Rate/100) = IGST

Net Price + IGST = Gross Price

If Input Tax Credit (ITC) calculation is involved, the formula will be:

Purchases x GST Rate/100 = ITC Available 

Tax Payable on sales – ITC Available = NET GST liability 

While these formulas are important to calculate GST, you cannot solely rely on them. In-depth research and assurance of accurate computation along with compliance are necessary, and that can be achieved with the help of a professional tax advisor or a tax expert. 

GST calculations for purchase 

GST calculation for purchases is considered a critical element but is important too. The GST calculation for purchases can have an impact on the cost structure, the cash flow management, and the tax liability as well. 

However, the situation can easily be managed with the application of the right formulas, practical considerations, and taking care of the fundamentals. 

There are different purchase cases, and each situation has its own formula. These are: 

  1. When the purchase of the good is within the state: 

Net price x CGST Rate 

——————————- = CGST


Net price x (SGST/UTGST/ Rate/100) = SGST/UTGST

Net Price + CGST+ SGST/UTGST = Gross price

For the interstate purchases, the formulas will be :

Gross price * net price + IGST

Net price * (IGST Rate)

——————————- = IGST


Apart from these formulas, what’s important is to keep in mind some of the thoughtful considerations:

  • Reverse Charge Mechanism (RCM) in GST
  • HSN code classification 
  • Compliance and deadlines 
  • Staying updated with all the relevant information 
  • Seeking help from a tax expert

Different GST rates and categories 

There are four different tax rates, and each one of them is levied on different goods and services. The taxes are categorized as follows:

  1. 28%: This is recorded as the highest GST rate, and this rate is generally applied to goods that come under the category of luxurious items. These can be perfumes, high-end makeup, cars, or skincare products. 
  2. 18%: Certain goods are charged a GST of 18%, including washing machines, televisions, durables, and furniture. 
  3. 12%: This tax rate is generally applied to goods that are in daily use, such as footwear, food and beverages, textile garments, or phones. 
  4. 5%: This rate is applied to items that come under the category of unbranded foods and other materials such as grains, wheat, cereal, eggs, and textbooks.  

Some other taxes are listed below: 

  1. 0%: Certain goods are exempted from paying any tax. These are either related to food items, agriculture, or education. 
  2. 3%: All the products that are made up of gold are charged at 3%, and an additional cess of 0.5% is also charged on goods that are made up of gold. 
  3. Nil: There are certain goods upon which the tax is considered nil. This means that there will be no tax charged on that good. 

One of the important things to do is stay updated whenever you are in the business of trading. It’s essential to know the evolving landscape of GST rates, any sudden downfall or increase in the rates, and if there are any new rules or laws that have been recently implied on the GST portal. It’s quite important to know what’s happening around us. 

Advanced concepts in GST Calculations 

Some advanced concepts need thorough attention, along with the calculation of GST. These are: 

  1. Composite supply: It occurs when the supply of goods and services involves a single transaction. In this scenario, the tax is applied to the entire package at the same rate. 
  2. Mixed supply: This includes the taxable and non-taxable supply of goods in a single transaction. 
  3. Imports: When it comes to importing goods, it’s essential to understand the exemptions for certain goods. 
  4. Exports: Most exporting goods are exempt from paying any taxes. However, some documents need to be taken care of. 
  5. Tools and automation: It’s helpful to use tools and software to automate the process. The more automated the process is, the less chance there is of any error. Also, this way, it will consume less time. 

Keeping the process up to date and using tools that are used to modernize the process can help keep up with the trend, stay up to date, and also help cater the process smoothly and efficiently. Also, it’s better if you stay updated with common mistakes in GST calculation so that you don’t repeat them. 

Best practices and tips for accurate GST calculation

For best practices and tips to ensure correct GST calculation, it’s important to strengthen your concepts regarding tax rates and the categories (tax slabs) as per the goods and services. You should know which formula to apply and find the correct values and GST rates out of it and you should stay up to date regarding tax compliance, the recent changes in the GST rules, and all the hassle related to the documentation. 

Keeping these points in mind helps you ace success and make things go smoothly and efficiently as well. Some other tools help you practice in the best manner for accurate GST calculation. 

  1. The first is to use tools and software that help automate the system from top to bottom. Manual calculation is time taking and there are chances of mistakes as well. 
  2. Accounting software is the best investment when it comes to calculating GST. 
  3. You can get help from online GST calculators instead of doing it manually to save time and effort, and the calculation will also be error-free. 
  4. If you are looking for smooth and efficient compliance, fast credit settlement, and better data privacy and security, if there is anything that can help you regarding these, it can be e-invoicing platforms. 


It requires thorough understanding, research, and expertise to calculate GST rates for sale and purchase. You cannot claim GST calculation as a compliance burden. 

It’s equally important to know and calculate GST to excel in financial systems, for businesses and consumers, and for economic growth as well. 

Businesses can avail of great benefits once they excel in calculating the GST. The benefits can be:

  1. It helps in improving cash flow management
  2. It helps enhance decision-making
  3. It helps in maintaining competitive pricing and financial transparency
  4. It helps in timely tax reporting 

Since the landscape of taxation keeps changing, so do the various methods of calculation as well. It’s best to acknowledge these changes and learn new tactics as well.


Q1. How do you calculate GST purchase and sale?

The GST of any good can be calculated by the following formula:

Original cost x GST rate %

———————————-   = GST Amount


The net price can be calculated as = GST amount + original price. 

Q2. How do you calculate GST from total sales?

Simply get the amount multiplied by 1.1 without including the GST amount. This way, you will figure out the cost. To find out the GST component, you simply divide the GST, including the price of the goods, by 11. 

Q3. What is the proper way to calculate GST?

Whatever the total price of any product is, get that sum divided by 11. To know what the price of that particular product was before GST, divide its price by 1.1. 

However, these calculations are time-consuming and it gets difficult to find out the value every time; therefore, it’s recommended to use a calculator for that. It saves time and quickly gets the total sum out of it. 

Q4. What is the GST rate?

The rate of GST differs in various countries for different categories of products. They are divided into different slabs. These are:

28% GST, which is the highest recorded in India, 18% GST, 12% GST, and 5% GST. However, it varies according to the different GST rules being followed in each country. 

Q5. What is the total invoice value in GST?

The total invoice value in GST is the total sum of the value that is taxable plus the total GST amount. 

GST amount + sum of total taxable value = total invoice value

Q6. What is the GST on sales called?

The GST that is charged on sales is called the output tax. Any GST rate that is paid at the time when any good is purchased is called an input tax. Later on, the trader is supposed to collect the GST during the sale, as it is termed an output tax. 

Q7. Which product has the highest GST rate?

The highest GST has been recorded on luxurious items. 

Q8. What is the time limit for the GST invoice?

The time limit for the GST invoice is mentioned to be within 30 days. 

Q9. What are the types of invoices in GST?

  1. Retail invoices: These include various other cases such as local sales to register, central sales, and local sales tax-free
  2. Tax invoices: In which local sales to the registered dealer are taxable.

Q10. Which input GST is chargeable?

When the purchase of the goods is made, which takes place in a general business transaction, then the input GST is made chargeable. 

Spread the love

Amitha Shet

Amitha is a creative enthusiast, which gets her into educating the world about things she comprehends. Finance, business, and digital transformation are the topics that she is profoundly interested in so that she can make things simpler for the audience. She is currently a content strategist for a fintech company. She holds a Bachelor of Engineering in Civil Engineering, although finance is a niche that piques her interest to not just educate but to invest and gain experience.

Leave a Reply