Calculate the pre-tax price instantly.
Enter any tax-inclusive amount and get the original price before tax. Works with GST, VAT, sales tax, or any custom rate.
Reverse tax calculator.
Enter the total amount including tax and the tax rate to find the original pre-tax price.
The final price you paid including tax
GST, VAT, or sales tax percentage
How it works.
Enter total amount
Input the final price you paid, including any tax that was added.
Set your tax rate
Choose from common presets (GST, VAT) or type in any custom percentage.
Get your results
Instantly see the original pre-tax price and the exact tax amount breakdown.
What Is a Reverse Tax Calculator?
A reverse tax calculator is a free online tool that helps you figure out the original price of something before tax was added. When you look at a receipt, the total you paid already has tax baked in. This tool works backward from that final number to tell you exactly how much was the actual price and how much went to tax.
This is the opposite of a regular tax calculator. Instead of adding tax to a price, a reverse sales tax calculator removes it. Whether you're trying to separate GST from a purchase in India, figure out VAT on an invoice from the UK, or break down sales tax on a receipt from Texas or New Jersey, the process is the same — you just need the total amount and the tax rate.
The Reverse Tax Formula
The math behind a reverse tax calculation is straightforward. Here's the formula:
Pre-tax Price = Total Amount ÷ (1 + Tax Rate ÷ 100)
Once you have the pre-tax price, finding the tax amount is simple subtraction:
Tax Amount = Total Amount − Pre-tax Price
That's it. No complicated accounting knowledge needed. You divide the total by a factor based on the tax rate, and out comes the original price.
A Real-Life Example
Let's say you bought a pair of headphones and your receipt shows ₹1,180. You know the GST rate on electronics in India is 18%. You want to find out what the headphones actually cost before the government's cut was added.
Using the reverse tax formula:
Total paid: ₹1,180
Tax rate: 18%
Pre-tax price = 1,180 ÷ (1 + 18/100)
Pre-tax price = 1,180 ÷ 1.18
Pre-tax price = ₹1,000
Tax amount = ₹180
So the headphones actually cost ₹1,000, and ₹180 of what you paid was GST. Simple as that. The same logic works whether you're dealing with 5% GST on groceries, 20% VAT on a purchase from Europe, or 8.875% sales tax on something you bought in New York.
Who Uses This Tool?
Freelancers and small business owners use it to separate tax from their gross receipts for bookkeeping. Shoppers use it to double-check whether they were charged the correct rate. Accountants reach for it during audits when they need to quickly verify tax breakdowns across dozens of invoices. If you've ever stared at a receipt wondering "how much of this was actually tax?" — this is your answer.
Works with Any Tax Rate, Anywhere
Tax rates vary wildly depending on where you are. Sales tax in Texas is 6.25%, in New Jersey it's 6.625%, and in New York it can go up to 8.875% with local surcharges. The UK charges a flat 20% VAT. Canada has a 5% federal GST, though provinces like Alberta keep it at just the federal rate while others combine it with provincial sales tax. Australia uses a flat 10% GST, and India has four GST slabs ranging from 5% to 28%.
Our calculator handles all of these. Just enter the total and the rate — it doesn't matter if you're in Calgary, Chennai, London, or Austin. The formula works the same everywhere, and you'll get your answer in less than a second.
No sign-ups, no limits on how many calculations you can do. Enter your amount, pick your rate, and get the breakdown instantly.
Frequently Asked Questions
How do I calculate the original price before GST, VAT, or sales tax?
Divide the total (tax-inclusive) amount by (1 + tax rate ÷ 100). For example, if you paid $118 and the tax rate is 18%, the original price is $118 ÷ 1.18 = $100. This works for any tax type — GST, VAT, or sales tax.
Can I use this calculator for split taxes like CGST + SGST?
Yes. For split tax structures like India's CGST and SGST, simply enter the combined rate. For instance, if your invoice shows 9% CGST + 9% SGST, enter 18% as the tax rate. The calculator will give you the correct pre-tax amount, and you can split the tax portion equally between CGST and SGST.
Why does subtracting the tax percentage give a wrong answer?
Because tax is calculated on the pre-tax price, not on the total. If an item costs $100 and tax is 18%, the total is $118. But 18% of $118 is $21.24 — not $18. That's why you must divide by (1 + rate) instead of subtracting the percentage. Subtracting always over-estimates the tax amount.
What's the difference between tax-inclusive and tax-exclusive pricing?
Tax-inclusive pricing means the displayed price already contains tax (common in the UK, Australia, and India). Tax-exclusive pricing means tax is added on top at checkout (common in the US and Canada). A reverse tax calculator is designed for tax-inclusive amounts — it extracts the hidden tax from the total you already paid.
How do I reverse calculate tax from a total amount on a receipt?
Take the total from your receipt and identify the tax rate that was applied (check the receipt, or look up your local rate). Enter both values in the calculator. It will instantly show you the pre-tax price and the exact tax amount. This works for any receipt — retail, restaurant, services, or online purchases.
Does this tool work for compound taxes or multiple tax layers?
For simple combined taxes (like GST = CGST + SGST), just add the rates together and enter the total. For true compound taxes where one tax is applied on top of another (like PST applied after GST in some Canadian provinces), you'll need to reverse-calculate each layer separately — first remove the outer tax, then remove the inner tax from the result.
Can businesses use reverse tax calculations for filing returns?
Reverse tax calculations are useful for quick verification and bookkeeping — checking invoice breakdowns, reconciling receipts, or estimating tax components. However, for official tax filings, businesses should use their accounting software or consult a tax professional to ensure compliance with local regulations and input tax credit rules.
What's the difference between GST, VAT, and Sales Tax?
GST (Goods and Services Tax) and VAT (Value Added Tax) are multi-stage taxes collected at every point in the supply chain, with credits for tax already paid at earlier stages. Sales Tax is a single-stage tax collected only at the final sale to the consumer. GST is used in India, Australia, Canada, and Singapore. VAT is used across Europe, the UK, and the Middle East. Sales Tax is used in the United States. Despite these structural differences, the reverse calculation formula is identical for all three — you always divide the total by (1 + rate).