Guides · Updated 30 September 2026 · Sources at the end
The short answer
Yellow means danger and no overtaking; double waved yellow, great danger. Red stops the session. Blue tells a driver a faster car is behind. Green means all clear. Black with a car’s number calls it in; chequered ends the race. The full list below comes from Motorsport UK’s circuit racing regulations (Q12.24).
Every flag
GreenWaved
All clear at the end of a danger area controlled by yellow flags. Also shown at every post on the first lap of each practice session and on each formation lap.
YellowWaved
Danger. Slow down enough to keep full control. No overtaking.
Yellow, double wavedTwo flags waved
Great danger. Slow down considerably, be ready to leave the racing line or stop. No overtaking. May be backed up or replaced by flashing yellow lights.
Yellow with red stripesStationary / waved
Slippery surface ahead (stationary) or imminent (waved).
BlueStationary / waved
Another competitor is close behind (stationary) or trying to overtake (waved). Ignoring waved blue flags gets you reported.
White
A service car or slow-moving car is on the circuit: waved in the sector where it is, held still in the next.
Red
Stop racing. Slow down, no overtaking, and go carefully to the pits or start line as the marshals direct.
Purple (Code 60)
Neutralises the race when the organisers use Code 60, under its own procedure explained at the drivers' briefing.
Black with orange disc, plus a number
That car appears to have a mechanical problem or fire the driver may not know about. It must pit next lap.
Black and white diagonal, plus a number
A warning about the driver's behaviour; more reports may bring the black flag.
Black, plus a number
Stop at your pit next lap and report to the Clerk of the Course. Can mean disqualification.
Chequered
End of the race or practice. Once shown, the event is over.
At an incident
Where the track is blocked or marshals are working, drivers see a waved yellow at the post before, double waved yellows at the post just before the incident, and a waved green at the post just after it. Overtaking is banned from the first yellow until the green. If yellows are withdrawn while a hazard remains, a Hazard Area board marks it instead.
See them live
Every board on AllRace Live shows the session’s current flag: green, yellow, red or chequered. Pro members can get a push when a red flag stops a session they follow.
Questions
What does a yellow flag mean in racing?
Danger ahead: slow down enough to keep full control, and no overtaking. Double waved yellows mean great danger: slow down considerably and be prepared to stop.
What does a blue flag mean?
Held still, another competitor is close behind. Waved, a faster car is trying to overtake and the driver must let it past at the first opportunity.
What does the black flag with an orange circle mean?
Shown with a car's number, it warns of a mechanical problem or fire the driver may not know about. The car must come into its pit on the next lap.
What does a red flag mean?
The session is stopped. Drivers slow down, stop overtaking and drive carefully to the pits or start line as marshals direct.