Guides · Driving in France

Speed camera tolerance in France: how the adjusted speed is calculated

The margin of a fixed speed camera in France is 5 km/h when the measured speed is below 100 km/h, and 5 % above. It is deducted from the measured speed to give the adjusted speed, the only one used for the penalty. It is not a tolerance that lets you speed: an offence is recorded from 1 km/h over the limit in adjusted speed.

See speed cameras on the map The Vigirota app

Be warned out loud before every speed camera on your route. The free Vigirota app reads them out as you drive (in French for now). On iPhone: soon — the online map already works.

Key points

Fixed camera: 5 km/h margin below 100 km/h, 5 % of the measured speed from 100 km/h.
Adjusted speed = measured speed − technical margin. It is shown on the notice and decides the penalty.
The margin allows no speeding: it corrects the device's inaccuracy, it does not move the limit.
There is no '+10 km/h' rule on French fixed cameras.

What is a speed camera's margin of error?

The margin of error, or technical margin, is the measurement uncertainty recognised for a speed enforcement device. It comes from the French order of 4 June 2009 on road enforcement speed meters, which sets a maximum permissible error for each device. This margin is always deducted from the measured speed, in the driver's favour.

Be careful with the word 'tolerance': it is not permission to drive a little faster. The margin corrects the measuring instrument's own inaccuracy; it does not move the speed limit. Driving at the exact limit remains the right rule, and the limit in force is always the one shown by the signs.

What is the margin of a fixed speed camera?

For a fixed camera in service, the maximum permissible error is 5 km/h when the measured speed is below 100 km/h, and 5 % of the measured speed from 100 km/h. This value is subtracted to obtain the adjusted speed. Below 100 km/h the margin is fixed; above, it grows with the speed.

New or repaired devices are checked more strictly (3 km/h below 100 km/h, 3 % above), but it is the margin for devices in service (5 km/h / 5 %) that applies to your fine.

From measured speed to adjusted speed: worked examples

The adjusted speed is the only one that counts legally: it appears on the notice and decides the fine. It is the measured speed minus the technical margin. Here are examples for a fixed camera (they illustrate the rule, they are not official cases).

Limit	Measured speed	Margin deducted	Adjusted speed	Offence?
50 km/h	54 km/h	5 km/h	49 km/h	No
50 km/h	56 km/h	5 km/h	51 km/h	Yes (+1)
80 km/h	86 km/h	5 km/h	81 km/h	Yes (+1)
110 km/h	116 km/h	5 % ≈ 5.8 km/h	≈ 110 km/h	Borderline
130 km/h	137 km/h	5 % ≈ 6.8 km/h	≈ 130 km/h	Yes

Examples for a fixed camera in service (5 km/h below 100 km/h, 5 % above). The adjusted speed is rounded down to the whole number on the notice.

The myth of 'they only flash at +10'

It is false. The margin is not a trigger threshold: it is a correction for uncertainty. An offence is recorded as soon as the adjusted speed exceeds the limit by a single km/h. At 50 km/h, an adjusted speed of 51 km/h is enough, which corresponds to a measured speed of about 56 km/h. There is no 10 km/h margin on fixed cameras.

Only one case gives a wider margin: devices that measure from a moving vehicle, for which the margin usually quoted is 10 km/h below 100 km/h and 10 % above. This does not apply to fixed cameras.

Small excesses and penalty points

Since 1 January 2024, an excess of less than 5 km/h (in adjusted speed) no longer costs a penalty point on a French licence: the fine is still due, but the points are not touched. This comes from decree no. 2023-1150 of 6 December 2023 and does not change the device's margin.

The fines for larger excesses are in speeding fines in France. To anticipate the enforcement areas on your route, the Vigirota Radar app reads them out, and Vigirota Maps (maps.vigirota.fr) shows them with the speed limit in force.

Frequently asked questions

What is the margin of a camera at 50, 80 or 130 km/h?

For a fixed camera: 5 km/h below 100 km/h, so 5 km/h at 50 and at 80 km/h. From 100 km/h the margin becomes 5 % of the measured speed, about 6.5 km/h for a reading around 130 km/h.

How fast do you have to go to be flashed at 50 km/h?

The adjusted speed must exceed 50 km/h, so reach at least 51 km/h. After deducting the 5 km/h margin, that is a measured speed of about 56 km/h. There is no +10 km/h threshold.

Is the margin a tolerance that allows speeding?

No. It is the device's margin of error, deducted automatically from the measured speed. It corrects the measurement's inaccuracy; it does not allow you to exceed the limit.

Does a mobile camera have the same margin as a fixed one?

No. A device measuring from a moving vehicle applies a wider margin, usually quoted as 10 km/h below 100 km/h and 10 % above. Fixed cameras stay at 5 km/h / 5 %.

Where is the adjusted speed on the notice?

The notice shows both the measured speed and the adjusted speed. Only the adjusted speed, after deducting the margin, is used to calculate the fine.

Official sources

Last checked: 4 October 2026. This page is a translation of our French guide; the French Highway Code is the only official text.

Be warned in time, without reading anything at the wheel

Vigirota Radar reads out the enforcement zones, shows the speed limit in force and guides you to your destination. Free, no sign-up, in French for now.

Soon