VAT Invoice Calculator
Enter up to three line items with their quantity and unit price, choose a VAT rate, and the calculator works out each line, the subtotal and the VAT-inclusive total.
A VAT invoice must show the net, the VAT rate and the VAT amount — this gives you all three.
How the calculation works
We believe numbers should be transparent. Here is the formula behind this calculator.
Worked example
Worked example: 2 × £100 + 3 × £50 at 20% VAT
Important assumptions
- Unit prices are entered net of VAT; VAT is added on the subtotal.
- All lines use the same VAT rate — mixed-rate invoices need separate sections.
- Quantity is rounded up in the line totals; a zero quantity line contributes nothing.
Rates & official sources
Every calculation is based on the official rates and rules published by GOV.UK and HMRC.
Frequently asked questions
What must a VAT invoice show?
A VAT invoice must show the seller's name and address, your name and address, a unique invoice number, the date, the description, the net amount, the VAT rate and the VAT charged.
Do I charge VAT on every line?
Only if your supply is taxable. Some goods are zero-rated or exempt, and some customers (like overseas businesses) may not be charged UK VAT. This calculator uses one rate across the invoice.
Can I round the VAT amount?
Yes — HMRC allows rounding to the nearest penny. This calculator keeps exact figures; your accounting software will round the total for the invoice.
Related calculators
VAT Calculator
Add or remove VAT, see the VAT amount and the VAT-inclusive or VAT-exclusive price.
View calculatorVAT Profit Calculator
Work out net profit and the VAT you owe HMRC from your sales and purchases.
View calculatorPercentage Calculator
Three quick percentage tools: percentage of an amount, comparing amounts and percentage change.
View calculatorRelated guides
New to the topic? Read a plain-English guide on vat, with worked examples and tips.
These calculations are estimates for guidance only and are not professional financial, tax or legal advice. UK rates and rules change, so always verify important figures with official GOV.UK / HMRC information or speak to a qualified professional. See our full disclaimer.