VAT & Sales Tax Calculator

Add or remove VAT or sales tax at any rate: see the tax amount and the price with and without tax.

Tax amount

£20.00

Add tax

Excluding tax

£100.00

Including tax

£120.00

Please note: This is an example calculation, not financial advice. Personal circumstances, changes in rules and rates, and additional costs are not included. If in doubt, talk to a financial adviser.

How this number is calculated

The blocks use your input. Change a value above and they update with it.

Step 1 · Rate as a factor

Tax rate (%)20 ÷ Per100 =Rate as a factor0.2

Step 2 · Amount excluding tax

(Calculation: Add tax) Amount£100.00 =Amount excluding tax£100.00

Step 3 · Tax

Amount excluding tax£100.00 × Rate as a factor0.2 =Tax£20.00

Step 4 · Including tax

Amount excluding tax£100.00 + Tax£20.00 =Including tax£120.00

How the calculation works

Work out how much VAT or sales tax is in a price, or what a price becomes once tax is added. Enter any rate, so it works for every country and state.

Add tax: the tax is the amount times the rate, and the price including tax is the amount plus the tax. Remove tax: the amount excluding tax is the amount divided by (1 + rate); the difference with the amount you entered is the tax. All results are rounded to whole cents, half a cent upwards.

Formula

Add tax: tax = amount × rate ÷ 100. Remove tax: excluding = amount ÷ (1 + rate ÷ 100), tax = excluding × rate ÷ 100.

Assumptions

One tax rate applies to the whole amount.
The rate you enter is the full rate, for example state, county and city sales tax added together.
Each result is rounded to whole cents, half a cent upwards.
Exemptions, reverse charge and other special schemes are not included.

Example calculations

The button fills in the calculator above, so you can carry on from there.

Invoice, adding 20% VAT

Tax amount
£170.00

Amount £850.00 · Tax rate (%) 20 · Add tax
Receipt, taking out 20% VAT

Tax amount
£4.00

Amount £23.99 · Tax rate (%) 20 · Remove tax
Sales tax at the checkout

Tax amount
£16.25

Amount £249.99 · Tax rate (%) 6.5 · Add tax

Frequently asked questions

How do I remove VAT from a price?

Divide the price including VAT by 1 plus the rate as a decimal. With 20% VAT, divide by 1.2: a price of 120 is 100 excluding VAT, so the VAT is 20.

Why is 20% of the price including VAT not the VAT?

The rate applies to the price excluding VAT. In a price including 20% VAT, the VAT is 20/120 of the total, which is one sixth or about 16.67%.

How is US sales tax different from VAT?

Sales tax is added at the checkout and is usually not included in the price on the shelf. The rate depends on the state and often the city or county, so combine both into one rate here. VAT is charged at every step of the supply chain and is normally already included in consumer prices.

How do I add sales tax to a price?

Multiply the price by the tax rate as a decimal and add the result to the price. With 8% sales tax, 50 becomes 50 + 50 × 0.08 = 54.

What is GST?

GST (goods and services tax) is the name used for VAT in countries such as Australia, New Zealand, Canada and Singapore. It is calculated the same way, so you can enter the GST rate here.

Why is my receipt a cent different?

Shops may round the tax per item instead of over the total, which can make a difference of a cent or two. This calculator works out the tax over the whole amount and rounds the result to the cent.

Sources and checks

Sources

VAT rates | GOV.UKgov.uk · accessed 5 October 2026
Providing price information | Business Companion (Trading Standards)businesscompanion.info · accessed 5 October 2026

How we check it

This calculator has 14 fixed checks: 11 calculations with a result that is fixed in advance, and 3 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.

See the calculations

Amount £100.00 · Tax rate (%) 20 · Add tax → Tax amount £20.00
Amount £120.00 · Tax rate (%) 20 · Remove tax → Tax amount £20.00
Amount £50.00 · Tax rate (%) 7.25 · Add tax → Tax amount £3.63
Amount £10.99 · Tax rate (%) 5 · Add tax → Tax amount £0.55
Amount £10.00 · Tax rate (%) 19 · Remove tax → Tax amount £1.60
Amount £50.00 · Tax rate (%) 0 · Remove tax → Tax amount £0.00
Amount £0.00 · Tax rate (%) 20 · Add tax → Tax amount £0.00
Amount £1,000,000,000.00 · Tax rate (%) 100 · Add tax → Tax amount £1,000,000,000.00
Amount £850.00 · Tax rate (%) 20 · Add tax → Tax amount £170.00
Amount £23.99 · Tax rate (%) 20 · Remove tax → Tax amount £4.00

Changes

5 October 2026: Sources added and content reviewed.
4 October 2026: First version.

Last reviewed: 5 October 2026 · How we build and check our calculators