Average speed cameras: your average speed and the fine
An average-speed camera does not catch you at one spot: it divides a distance by a time. Enter both and the tool does the rest.
An average-speed camera, known in France as a radar tronçon, photographs every vehicle at the start and end of a stretch of road a few kilometres long, then divides the distance by the travel time. The Interior Ministry’s file lists 66 in France as of 30 December 2025. Its average speed is treated like that of a fixed camera: the margin of 5 km/h, or 5% above 100 km/h, is subtracted, then the excess follows the ordinary scale of article R413-14. Braking hard at the exit achieves nothing, since only the average counts, and driving fast at the start and slowly at the end can give a lawful average. Example: 3.2 km covered in 1 minute 50 gives an average of 104.7 km/h; on a 90 section the recorded speed is 99 km/h, no offence. In 1 minute 40, the average rises to 115.2 km/h and the excess appears.
Standard fine · class 3
€68
1 point · 9 km/h over the limit
| Recorded speed (margin 5.2 km/h) | 99 km/h |
| Reduced, paid within 15 days | €45 |
| Increased, after 45 days | €180 |
| Points deducted | 1 |
| Licence suspension risked | no |
| Points back with no new offence | after 6 months |
Checked by Radif Partners · Editorial policy · Method and sources
The formula
Average speed = distance in kilometres × 3,600 ÷ time in seconds. The section length is set by the authorities; the time is the gap between the two photographs. The margin from the order of 4 June 2009 is then taken off, as for a fixed camera.
| Time over 5 km | Average speed | Recorded | On a 90 section |
|---|---|---|---|
| 3 min 30 | 85.7 km/h | 80 km/h | no offence |
| 3 min 20 | 90.0 km/h | 85 km/h | no offence |
| 3 min 10 | 94.7 km/h | 89 km/h | no offence |
| 3 min | 100.0 km/h | 95 km/h | €68, 1 pt |
| 2 min 45 | 109.1 km/h | 103 km/h | €68, 1 pt |
| 2 min 30 | 120.0 km/h | 114 km/h | €135, 2 pt |
Average-speed camera: my average
Average speed
100.0 km/h
| Recorded speed | 95 km/h |
| Fine | €68 |
| Points | 1 point |
Why time matters more than the speedometer
Over five kilometres, ten seconds less is enough to take an average from 90.0 to 94.7 km/h. Cruise control set at the limit is the simplest way to stay under the threshold, since the camera margin absorbs small speedometer gaps. The other bands of the scale, and the switch to class 4 on a section limited to 50 km/h, are on the small excess page.