GST / VAT Calculator in your browser, no signup

Adding tax to a price is easy arithmetic. Removing it is where people get it wrong, and the mistake costs real money on invoices. If VAT is 20% and the tax-inclusive price is £120, the pre-tax amount is not £120 minus 20%. That gives £96, which is wrong. The correct answer is £100, because the £20 of tax was calculated on £100, not on £120. Subtracting the percentage from the final figure always understates the base and overstates nothing - you divide by 1.20 rather than multiplying by 0.80. The gap widens with the rate: at 20% the error is £4 on a £120 invoice, and it compounds across every line of a VAT return. This calculator handles both directions correctly, which is the entire point. Rates are yours to enter, since VAT and GST vary by country and often by product category within one country. Everything runs in your browser.

These numbers are the kind you check twice before sending a quote, a tax form or a loan application. The tool does the arithmetic; you still own the inputs.

GST / VAT Calculator is a good fit when preparing an invoice that must show net, VAT and gross separately.

In plain English

GST / VAT Calculator is built around a few practical wins, not a long feature list:

• Removes tax correctly by dividing rather than subtracting a percentage, which is the error most manual calculations make.
• Works in both directions, covering invoicing and expense reconciliation.
• Any rate, so it fits every country and reduced-rate category.
• Shows net, tax and gross together - the three figures an invoice must display.
• Runs in your browser with no account.

How to run it

1. Choose add or remove. Add takes a pre-tax price to a final price. Remove works backwards from a tax-inclusive total.
2. Enter the amount. Whichever figure you have - the net price or the gross total.
3. Enter your tax rate. Your local VAT or GST rate. Many countries apply reduced rates to specific categories, so check which applies.
4. Read all three figures. Net amount, tax amount and gross total together - which is what an invoice needs to show.

Real situations

• Preparing an invoice that must show net, VAT and gross separately.
• Working out the pre-tax value of a receipt for an expense claim.
• Pricing a product to hit a specific tax-inclusive shelf price.
• Reconciling supplier invoices where only the gross total is stated.
• Checking a quoted price is genuinely tax-inclusive as claimed.

Small habits that help

• Never subtract the percentage to remove tax. Divide by 1 plus the rate - dividing £120 by 1.20 gives the correct £100.
• Check which rate applies. Many countries use reduced rates for food, books, children's clothing and energy.
• State net, tax and gross separately on invoices. Most tax authorities require it.
• When quoting to businesses, quote excluding tax; to consumers, quote including it. That is the normal convention in both directions.
• Keep your records in the same direction as your invoices, or reconciliation becomes needlessly painful.

Skip these

• Subtracting 20% from a gross figure to find the net amount. It is wrong every time, and wrong by more as the rate rises.
• Applying the standard rate to goods that qualify for a reduced or zero rate.
• Quoting a price to a consumer excluding tax, which is prohibited in many jurisdictions.
• Rounding tax per line rather than per invoice, which produces small discrepancies that accumulate.
• Assuming GST and VAT rules are identical across borders. The mechanism is similar; the rules and rates are not.

Does anything leave your device?

GST / VAT Calculator runs in your browser. The file or text you paste stays on your device. There is no account, and nothing is stored on a ToolBox server for this job.

Related tools worth opening next

If this is one step in a longer job, these usually come after it:

• Sales Tax Calculator - Add sales tax to a price or remove it from a total, for all 50 US states
• Free Invoice Generator - Create a professional invoice from 300 templates across 15 industries, with your logo, colours and font
• Profit Margin Calculator - Calculate profit, margin, markup, selling price, cost price and ROI

FAQ

What's the difference between "adding" and "removing" tax?

Adding tax takes a pre-tax price and calculates the final price including tax. Removing tax does the reverse - starting from a tax-inclusive final price, it works out what the original pre-tax amount was.

Does this use a fixed tax rate, or can I set my own?

You typically enter your own applicable tax rate, since GST/VAT rates vary significantly by country and even by product category in some places.

Is GST the same thing as VAT?

The mechanism is the same - tax collected at each stage of the supply chain and ultimately borne by the consumer. The name differs by country: VAT in the UK and EU, GST in Australia, India, Canada and elsewhere. The rules and rates differ substantially even where the principle matches.

How do I remove VAT from a price correctly?

Divide by 1 plus the rate, not subtract the percentage. At 20%, a £120 gross price divided by 1.20 gives £100 net. Subtracting 20% would give £96, which is wrong - and this is the single most common error in manual VAT calculations.

Why is subtracting the percentage wrong?

Because the tax was calculated on the smaller net figure, not the larger gross one. Twenty percent of £100 is £20, giving £120 gross. Taking 20% off £120 removes £24 instead, because you are applying the rate to a bigger number than it was originally charged on.

Are my figures stored anywhere?

No. All calculations run in your browser and nothing is transmitted.

Open the GST / VAT Calculator when you are ready. It is free, and you do not need an account.