Reverse GST Calculator
Understanding Your Results
Base Amount
The price before GST was added. This is the true cost you're paying for the goods or services. Use this for cost comparisons across suppliers and for budgeting purposes.
GST Amount
The tax component included in the total. This is what goes to the government. If you're a business, this may be claimable as input tax credit.
Total Amount
The amount you entered, confirming the calculation is based on the correct total. This is what you actually pay to the supplier.
What is Reverse GST Calculation?
Understanding how to find the base price from a total amount.
Real-World Examples
See how reverse GST calculation helps in different scenarios.
Australian Supplier Quote
Comparing supplier quotes for cost analysis
Calculation Steps
- Quoted Total: A$2,750
- GST Rate: 10%
- Base Price: A$2,750 ÷ 1.10 = A$2,500
- GST Amount: A$250
Indian Purchase Order
Determining actual product cost for budgeting
Calculation Steps
- Quoted Total: ₹29,500
- GST Rate: 18%
- Base Price: ₹29,500 ÷ 1.18 = ₹25,000
- GST Amount: ₹4,500
New Zealand Service Contract
Calculating base service fee for cost analysis
Calculation Steps
- Quoted Total: NZ$920
- GST Rate: 15%
- Base Price: NZ$920 ÷ 1.15 = NZ$800
- GST Amount: NZ$120
How to Use
Four simple steps to find the price before tax.
Select Country
Choose your country to load the correct GST rate. The calculator will automatically set the default rate for your region.
Enter Total Amount
Type the total price including GST. This is the amount quoted by your supplier or shown on the invoice.
Adjust Rate (Optional)
Change the rate if needed for special cases. The default rate is loaded automatically based on your country.
View Base Price
See the price before tax instantly. This is the true cost you're paying for the product or service.
Why Use This Calculator?
Key benefits of using our reverse GST calculator for cost analysis.
Quick Cost Analysis
Instantly find the base price from any total amount for accurate cost comparisons. No manual calculations needed, get results in seconds.
Supplier Comparison
Compare pre-tax costs when different suppliers quote with different tax treatments. Make apples-to-apples comparisons easily.
Accurate Budgeting
Know the true cost before tax for better budget planning and forecasting. Understand exactly what you're paying for the product or service.
Mobile-Friendly
Calculate on the go during supplier negotiations or purchasing meetings. Works perfectly on phones and tablets.
Parameters Explained
Understanding each input field and how it affects your calculation.
Total Amount (Including GST)
The total price with tax included, as quoted by suppliers. This is your starting point - the complete amount you would pay. For example, if a supplier quotes $110 including GST, enter 110.
GST Rate
The tax percentage to reverse calculate from. Each country has a standard rate: Australia 10%, New Zealand 15%, Canada 5%, India 18%, Singapore 9%. You can enter a custom rate if dealing with special tax zones.
Country
Determines default GST rate and currency symbol. Select your country to automatically load the correct settings. The calculator supports Australia, New Zealand, Canada, India, and Singapore.
Calculation Formulas
Mathematical formulas used to reverse calculate GST
Base Amount (Reverse Calculation)
This formula works backwards from the total to find the base price. Divide the total by (1 + rate as decimal) to get the amount before tax was added.
Base Amount = Total Amount ÷ (1 + GST Rate ÷ 100)
Example: Total: $110, Rate: 10% → Base = 110 ÷ 1.10 = $100
GST Amount
After finding the base amount, subtract it from the total to get the GST component. This shows you how much of the total price is tax.
GST Amount = Total Amount - Base Amount
Example: Total: $110, Base: $100 → GST = 110 - 100 = $10
Why This Works
The reverse calculation is the mathematical inverse of adding GST. If you know that adding 10% GST means multiplying by 1.10, then removing it means dividing by 1.10.
If Base × 1.10 = Total, then Total ÷ 1.10 = Base
Example: Forward: 100 × 1.10 = 110 | Reverse: 110 ÷ 1.10 = 100
Common Questions
Answers to frequently asked questions about reverse GST calculation.
Both use the same formula but serve different purposes. Reverse GST focuses on finding the base price for cost analysis and purchasing decisions. GST Inclusive focuses on extracting the tax amount for accounting purposes. Choose based on what you need to know - the pre-tax cost (Reverse) or the tax amount (Inclusive).
Use it when suppliers quote total prices including GST and you need to know the pre-tax cost. Perfect for comparing quotes from different suppliers, budgeting, or understanding true product costs. Essential for procurement and cost analysis.
Yes, enter any tax rate between 0.01% and 100%. The calculator works for GST, VAT, HST, or any similar consumption tax. Just enter your specific rate if it differs from the default country rates provided.
The calculator uses precise mathematical formulas and rounds to 2 decimal places. Results are accurate for business use, cost analysis, and purchasing decisions. The calculation follows standard accounting practices.
The base price is the true cost before tax. It's essential for comparing suppliers (who may quote differently), budgeting, calculating margins, and understanding your actual costs. Tax-inclusive prices can hide the real cost differences between suppliers.
Disclaimer
This calculator provides estimates for informational purposes only. Tax laws and rates may change. Always verify current GST rates with official government sources. For tax advice specific to your situation, consult a qualified tax professional or accountant. We are not responsible for any decisions made based on this tool.