Add VAT to a net amount, remove VAT from a total, or isolate the VAT amount on its own — at 20%, 5%, 0% or a custom rate. Built for quick, accurate invoice figures.
How to Calculate VAT on an Invoice
VAT is a tax added to most goods and services sold in the UK, charged as a percentage of the net price. When you’re preparing an invoice, three figures matter: the net amount (the price before VAT), the VAT amount (the tax itself), and the gross amount (what the customer actually pays, sometimes called the VAT-inclusive total).
To add VAT to a net figure, multiply it by the VAT rate as a decimal — for the standard rate, that’s VAT = Net Amount × 0.20. Add that to the net amount to get the gross total: Gross Amount = Net Amount + VAT.
Going the other way, if you already know the VAT-inclusive total and need to find the net amount, divide by 1 plus the rate: Net Amount = Gross Amount ÷ 1.20 at the standard rate. Subtracting the net from the gross then gives you the VAT amount.
Getting the rate right matters as much as the formula — standard-rated, reduced-rated and zero-rated supplies are all taxed differently, so check which applies to what you’re invoicing before relying on any single percentage. This calculator handles the arithmetic; it’s on you (or your accountant) to confirm the correct rate and whether VAT applies at all.
VAT Invoice Calculation Example
Adding VAT to a net amount
Removing VAT from a total
In the first example, £500 of VAT is added on top of a £2,500 net price to reach a £3,000 total. In the second, that same £3,000 is worked backwards to reveal the £2,500 net amount and the £500 of VAT sitting inside it.
What Should a UK VAT Invoice Include?
Beyond the net, VAT and gross figures, a proper VAT invoice generally needs to show:
- Unique invoice number
- Invoice date
- Date of supply (tax point), where applicable
- Supplier name and address
- Supplier VAT registration number
- Customer name and address
- Description of goods or services
- Quantity or extent of supply
- VAT rate applied
- Net amount
- VAT amount
- Total amount payable
Important: VAT rates and invoicing requirements can depend on the type of supply and your specific circumstances. This calculator is designed for general calculations and doesn’t determine whether a transaction is taxable or which VAT treatment applies.
Frequently Asked Questions
What is a VAT invoice calculator?
A VAT invoice calculator works out the net, VAT and gross figures for an invoice. You can add VAT to a net amount, remove VAT from a VAT-inclusive total, or find the VAT amount on its own, at whichever rate applies.
How do I calculate 20% VAT on an invoice?
Multiply the net amount by 0.20 to get the VAT, then add that to the net amount for the total. For example, £1,000 net at 20% gives £200 VAT and a £1,200 total.
How do I remove VAT from a total?
Divide the VAT-inclusive total by 1 plus the VAT rate as a decimal. At 20%, divide by 1.20 to get the net amount, then subtract that from the total to find the VAT.
What is the difference between net and gross?
The net amount is the price before VAT is added. The gross amount, also called the VAT-inclusive total, is the net amount plus VAT — it’s what the customer actually pays.
Can I calculate VAT at 5%?
Yes, the reduced rate of 5% is available as a preset alongside the 20% standard rate and 0% zero rate, and the same add or remove VAT formulas apply.
Can I use a custom VAT rate?
Yes, selecting the custom option lets you enter any percentage, which is useful for historic rates or situations outside the standard UK presets.
What information is required on a UK VAT invoice?
A VAT invoice typically needs a unique invoice number, the invoice date, supplier and customer details, the supplier’s VAT registration number, a description of the goods or services, the VAT rate, the net and VAT amounts, and the total. This calculator does not generate a compliant invoice on its own.
VATCalculatorX is an independent tool and isn’t affiliated with HMRC. For the official rules on what a VAT invoice must include, see GOV.UK’s invoicing guidance.