The short answer
12.5%. It is the figure on most London bills that carry a charge at all, and VisitLondon — London's official visitor site, published by the promotional agency London & Partners — tells visitors that restaurants often add a service charge, usually 12.5%, especially if you're in a large group. That is visitor guidance rather than a measurement, but it matches what people report.
There are signs of movement upward. Time Out has reported a shift toward 15% among London restaurants, in a piece from March 2025. That is press reporting on a trend rather than a measurement, and by now it is also 18 months old.
How little is actually known
This deserves stating plainly, because a lot of writing on the subject implies more certainty than exists. There is no figure for typical UK service charges in any legislation, in CMA guidance, in HMRC guidance, or in any government publication we could find. The government's own tipping consultations describe a charge often suggested as a percentage of the bill, and decline to say what percentage.
The frequently repeated “10% outside London” is a case in point: widely asserted, and we could not find a credible published source for it. It may well be roughly right. It is not something we are going to state as fact.
No legal rate, no cap
Nothing in law sets the percentage or limits it. A restaurant may charge 5%, 12.5%, 15% or nothing at all. What it must do is disclose the charge clearly and in time — the rate itself is a commercial decision.
What the percentage is applied to
Usually the food and drink total as it appears on the bill, which for consumers is normally VAT-inclusive — prices shown to consumers have to include tax. We haven't found a source establishing how often venues calculate on some other figure, so we aren't going to assert that they do. If the charge doesn't come to the percentage stated, the likelier explanations are a separate cover charge, a per-head minimum, or an arithmetic error — all of them fair to ask about.
Note also that a discretionary charge and a mandatory one are treated differently for VAT in the first place — that has its own page.
Filling the gap
The absence of decent data here is, more or less, why this site exists. Every entry in the directory records what a specific restaurant does, sourced either from a diner's report or from the restaurant's own published policy. One bill at a time is a slow way to build a picture of the country — but it produces a real answer for a real restaurant, which no national average ever does.
Look up where you're going, or add what was on your last bill.