VAT Calculator — Add or Remove Tax from Net & Gross Prices
Add VAT to a net price or extract VAT from a gross price at any rate.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
VAT and GST are charged on the net price, so the tax is always a percentage of the pre-tax amount rather than of the final total. Working out the VAT inside a gross figure means dividing by one plus the rate, not simply subtracting the percentage.
Worked example
calculated with the default values below
Amount 100 · VAT rate 20 % · Calculation Add VAT to a net amount Net amount 100.00 · VAT amount 20.00 · Gross amount 120.00
General background references
Disclaimer
These calculators give estimates for general information only. They are not financial, tax or investment advice and do not take your personal circumstances into account. Before borrowing, investing or filing, confirm the numbers with a qualified adviser in your jurisdiction.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
add: G = N×(1+r÷100); remove: N = G÷(1+r÷100); V = G−N
- N
- Net amount
- G
- Gross amount
- r
- VAT rate (%)
- V
- VAT amount
In add mode amount is net and G is computed; in remove mode amount is gross and N is computed; currency follows the amount input.
Frequently asked questions
Why does removing VAT divide by one plus the rate?
In remove mode the entered amount is already gross, so the tool recovers the net by dividing by one plus the rate rather than subtracting the percentage. At 20% on a 100 gross bill the net is 100 divided by 1.2, about 83.33, and the VAT is the 16.67 difference, not a flat 20. The add mode does the opposite, treating the input as net and adding 20% on top to reach 120. Mixing the two modes is the usual source of VAT miscalculation.