UK VAT Calculator
- No invented stats
- Written for UK readers
- Published 5 October 2026
This calculator works in both directions: add VAT to a price that excludes it, or pull the VAT back out of a price that already includes it. Pick the standard rate, the reduced rate, zero, or type your own. It shows the arithmetic alongside the answer, and it runs entirely in your browser — nothing you enter is sent anywhere.
How this works
Adding VAT is the easy direction. Multiply the net figure by the rate to get the VAT, then add it on. At 20%, £500 × 0.20 = £100 of VAT, so the gross is £600.
Taking VAT out of a gross figure is where people get caught. The instinct is to take 20% off the gross — and that is wrong. The 20% was charged on the net figure, not on the gross, so the VAT is 20% of a smaller number than the one you are looking at. To reverse it you divide:
net = gross ÷ 1.20 at the standard rate, or gross ÷ 1.05 at the reduced rate. In general, net = gross ÷ (1 + rate).
Why it matters: a £600 gross invoice divided by 1.2 gives £500 net and £100 of VAT. Multiplying £600 by 0.8 gives £480 — you would be £20 out on a single invoice, and understating your VAT by the same £20. The shortcut people use instead is the VAT fraction: at 20% the VAT is exactly one sixth of the gross (£600 ÷ 6 = £100), and at 5% it is one twenty-first.
The UK standard rate is 20%, the reduced rate is 5% and some goods are zero-rated. Those rates are correct at the time of writing, but rates and the categories they apply to do change — check the current position on the GOV.UK VAT rates page before you rely on a figure. The custom rate box is there for historic rates such as 17.5%, or for working with another country's rate.
A worked example
A customer asks for your price including VAT. Your net price is £500 and you charge the standard rate:
- VAT: £500 × 20% = £100
- Gross: £500 + £100 = £600
Later, a supplier sends you a receipt for £600 including VAT and you need the net figure for your accounts:
- Net: £600 ÷ 1.20 = £500
- VAT: £600 − £500 = £100 (the same thing as £600 ÷ 6)
- The wrong way: £600 × 0.80 = £480, which is £20 short
At the reduced rate the same £600 gross works out as £600 ÷ 1.05 = £571.43 net, with £28.57 of VAT.
What this doesn't account for
- Which rate applies. The calculator does the arithmetic; deciding whether something is standard, reduced, zero-rated or exempt is a separate question, and zero-rated is not the same as exempt.
- Whether you should be charging VAT at all. That depends on your registration status and the registration threshold.
- Rounding on invoices. HMRC allows more than one rounding approach on multi-line invoices, so a total worked out line by line can differ by a penny from one worked out on the total.
- Cross-border rules, reverse charge and special schemes such as the flat rate scheme, which changes what you actually pay over.
This is a calculator, not tax advice — check anything that matters with your accountant or on GOV.UK.
When you are quoting, be clear about whether your numbers include VAT: writing a sales proposal that gets signed covers how to lay out pricing, and dealing with procurement is worth a read before a purchasing team starts picking your quote apart. For margin work, always use the net figures — the profit margin and markup calculator explains why.
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