Add VAT vs. Exclude VAT
The same Amount field is interpreted differently depending on which option is selected. With Add VAT, the amount is treated as the price before tax, and VAT is added on top. With Exclude VAT, the amount is treated as a total that already includes VAT, and the calculator works backward to find the price before tax.
VAT = Amount × (Rate ÷ 100) Gross Amount = Amount + VAT Example: Amount 100, VAT 20% VAT = 100 × 0.20 = 20.00 Gross Amount = 100 + 20.00 = 120.00 Net Amount = Amount ÷ (1 + Rate ÷ 100) VAT = Amount − Net Amount Example: Amount 120, VAT 20% Net Amount = 120 ÷ 1.20 = 100.00 VAT = 120 − 100.00 = 20.00 Frequently asked questions
How do I add VAT to an amount?
Multiply the amount by the VAT rate as a decimal to get the VAT amount, then add that to the original amount. 100 at a 20% VAT rate gives 20.00 in VAT and a gross amount of 120.00.
How do I exclude VAT from a total?
Divide the total by 1 plus the VAT rate as a decimal to get the net amount, then subtract that from the total to get the VAT. 120 at a 20% VAT rate gives a net amount of 100.00 and 20.00 in VAT — note this isn't the same as simply subtracting 20% from 120.
Why can't I just subtract the VAT percentage directly from the total?
Because the VAT rate is a percentage of the net amount, not of the total. Subtracting 20% of 120 (which is 24) from 120 gives 96 — the wrong answer. The correct net amount is 100.00, found by dividing by 1.20, not by subtracting 20% directly.
How is this different from the other VAT Calculator?
This version uses a single amount field with an Add/Exclude toggle. The other VAT Calculator uses two separate tabs instead — one for finding the total from a net price and rate, and another for finding the VAT rate itself from a total and tax amount, which this simpler version doesn't calculate.