How do you back tax out of a price?

Divide the gross price by (1 + rate/100). For example, a gross of 120 at a 20% rate gives a net of 120 ÷ 1.20 = 100, so the tax portion is 20.

What is the difference between net and gross price?

The gross price includes tax, while the net price is the amount before tax is added. This tool finds the net from the gross.

Is my data sent anywhere?

No — every calculation runs locally in your browser and nothing is uploaded.

How do I work out the tax from a tax-inclusive total?

First find the net by dividing the gross by 1 + rate/100, then subtract it from the gross. On a £120 total at 20%, net is 100 and the tax is 120 − 100 = £20.

Why can I not just take 20% off the gross price?

Because the 20% was applied to the smaller net price, not the gross. Taking 20% off £120 gives £96, which is wrong. The correct net is £120 ÷ 1.20 = £100.

Does this work for VAT and GST too?

Yes. VAT, GST and sales tax all use the same percentage-of-net structure, so the same gross ÷ (1 + rate/100) formula backs any of them out of an inclusive price.

What rate should I enter?

Use the rate that was applied to the price — for example 20% for standard UK VAT, 9% for Singapore GST, or your local combined sales-tax rate. The tool accepts any percentage.

Reverse Sales Tax Calculator

Reverse sales tax calculator

Already know the tax-inclusive (gross) total and need the price before tax? Enter the gross amount and the tax rate, and this calculator backs the tax out, showing both the net price and the exact tax portion. It is useful for bookkeeping, expense claims and invoicing when only the final price is on the receipt.

How it works

Sales tax, VAT and GST are charged as a percentage of the net price, so to reverse them you divide rather than subtract:

net = gross ÷ (1 + rate ÷ 100) tax = gross − net

Taking the rate straight off the gross would overcount, because that percentage was originally applied to the smaller net figure.

Example

A receipt shows £120 including 20% VAT:

Figure	Value
Gross (inclusive)	£120.00
Net (120 ÷ 1.20)	£100.00
Tax portion	£20.00

Everything runs in your browser, so no figures ever leave your device.