What is the M25 speed limit? Variable limits, speed cameras and the Dartford Crossing

The M25 speed limit is 70 mph (112 km/h) for cars and motorcycles, and 60 mph (96 km/h) if you are towing a caravan or trailer. On most of the ring, though, overhead signs can set a lower mandatory limit, and the number in the red circle then becomes the limit for you. The Dartford Crossing, which carries the route over and under the Thames, has a limit of 50 mph (80 km/h).

What is the speed limit on the M25?

The speed limit on the M25 is 70 mph for cars and motorcycles unless a sign shows a lower one. That is the same national motorway limit you would have anywhere in Great Britain, and the Highway Code is clear that it is a maximum, not a target. Rule 125 calls the limit "the absolute maximum" and says it does not mean a speed is safe in every condition.

What is the M25 speed limit when towing?

The M25 speed limit when towing a caravan or trailer is 60 mph. This applies to cars, motorcycles, car-derived vans and dual-purpose vehicles. If a gantry shows 50 mph, that lower number applies to you as well.

What is the M25 speed limit for vans and lorries?

Most vans up to 7.5 tonnes laden can do 70 mph on the M25, or 60 mph if articulated or towing a trailer. Goods vehicles over 7.5 tonnes have a limit of 60 mph. The other common vehicles look like this:

• Motorhomes: 70 mph on a motorway, whichever side of 3.05 tonnes unladen they fall.
• Buses, coaches and minibuses up to 12 m long: 70 mph.
• Buses, coaches and minibuses over 12 m long: 60 mph.

Our guide to the national speed limit in the UK covers the same vehicles on other kinds of road.

Is the M25 a smart motorway?

Yes, most of the M25 is a smart motorway. The National Highways network map lists seven M25 sections, and the table above shows which type each one is. All of them can run variable speed limits, but they do not all look the same from the driver's seat.

What is a controlled motorway on the M25?

A controlled motorway uses technology to manage the speed of traffic and keeps a permanent hard shoulder. National Highways classes junctions 2 to 3, 7 to 10, 10 to 16, 16 to 23 and 27 to 30 this way. The stretch from junction 16 near Uxbridge to junction 23 near South Mimms is a good example: about 22 miles widened from three to four lanes each way, with gantries added, and operating as a controlled motorway since March 2014.

Which parts of the M25 are all lane running?

Junctions 5 to 7 and junctions 23 to 27 are all lane running, which means there is no permanent hard shoulder to rely on. The map notes one exception, with junctions 6 to 7 eastbound shown as a four-lane controlled motorway. If you break down on these stretches, our guide to smart motorways and variable speed limits explains what to do step by step.

Are there speed cameras on the M25?

Yes, there are speed cameras on the M25, and the camera sign on a gantry is the thing to look for. National Highways says camera signs mark sections of the motorway where vehicle speeds may be detected. We found no current public list of every M25 camera, so we do not quote a number.

National Highways provides the equipment and the police handle enforcement. According to National Highways, the camera records an image of the vehicle, its registration number, its speed, the time and date, and photographic evidence of the limit being displayed as the vehicle passes. That data goes straight to the regional police force, and National Highways says it has no access to it.

Do M25 speed cameras work when the signs are blank?

You should assume they do. We found no current statement from National Highways or the police saying that M25 cameras switch off when the signs are blank, and a limit always applies in any case. With nothing displayed and no earlier reduction, your limit is the national one for your vehicle.

Why did a speed camera flash on the M25 when I was within the limit?

It may have been a self-check. National Highways says that when a speed limit changes or a lane closes, the enforcement device runs a self-check and drivers passing it may notice a flash. The flash does not necessarily mean a vehicle has been identified as over the limit.

How do variable speed limits work on the M25?

Variable speed limits work by showing a mandatory number in a red circle on overhead or roadside signs, and that number stays in force until you are told otherwise. Highway Code rule 261 says you must not exceed a limit displayed within a red circle. National Highways adds that a limit in a red circle is always enforceable, whatever the reason for it, and that the reason may not be obvious from behind the wheel.

Three things are worth remembering on your next trip round:

• A blank sign changes nothing. National Highways says a blank or unlit display means the previous instruction still applies.
• The white circle with a black stripe ends the limit. A lower limit carries on until you pass the national speed limit symbol.
• A red X closes the lane. Highway Code rule 258 says you must not drive in a closed lane, so move across in good time.

So why does the limit drop when the road looks clear? National Highways lists traffic congestion that is happening or likely, roadworks, traffic officers working in vulnerable locations, extreme weather and incidents. The trouble may be a few miles ahead of you, and slowing early helps keep the traffic moving.

What is the speed limit on the Dartford Crossing?

The speed limit on the Dartford Crossing is 50 mph, in both directions. When the Dart Charge roadworks finished in 2015, Highways England said the 50 mph limit applied 24 hours a day and was enforced by average speed cameras. That announcement is the most recent statement of the limit we could confirm, so go by the signs on the day.

Is the Dartford Crossing a bridge or a tunnel?

It is both, depending on your direction. National Highways says the crossing links Essex and Kent by the QEII bridge for southbound traffic and two 1.4 km tunnels for northbound journeys. National Highways calls the crossing the A282, so strictly it is not part of the M25.

• Heading north: a height restriction applies to vehicles between 4.8 m and 5.0 m.
• At night: one tunnel often closes overnight for maintenance, and southbound traffic can be diverted through the east tunnel when the bridge closes.
• Charges: GOV.UK says the Dart Charge usually applies between 6am and 10pm, including weekends and bank holidays, and you pay by midnight the day after you cross.

Which part of the M25 is the busiest?

The busiest part of the M25 is the western side, with junctions 14 to 15 at the top of the national table. Department for Transport figures for 2025 put four M25 sections among the five busiest road sections in Great Britain:

1. M25 junctions 14 to 15: 213,000 vehicles a day
2. M25 junctions 13 to 14: 210,000 vehicles a day
3. M25 junctions 15 to 16: 209,000 vehicles a day
4. M25 junctions 12 to 13: 193,000 vehicles a day (fifth, behind one section of the M60)

All four sit on the stretch National Highways classes as controlled motorway, so these are the miles where you are most likely to see the gantries lit. Leave a little extra time here and keep at least a two-second gap, as Highway Code rule 126 advises on high-speed roads.

What roadworks are on the M25 in late 2026?

Several schemes were running on the M25 at the start of November 2026, and most of the disruption is overnight. Closures can change at short notice, so check before you set off.

• Junction 15 (M4 junction 4b): two major bridge expansion joints are being replaced, from autumn 2026 to winter 2027. Temporary ramps let the M25 reopen each day at the national speed limit, with work at night.
• Junction 3 (Swanley): traffic signals at the interchange are being upgraded from 31 October 2026 to April 2027.
• Junction 10 (Wisley): the project page lists a spring 2026 end date, yet was still announcing overnight closures in August 2026.
• Dartford Crossing: National Highways listed overnight tunnel closures through to mid-November 2026.

Around motorway roadworks, National Highways says 50 mph limits normally appear on temporary metal signs at the roadside, followed by a run of blank gantries. Highway Code rule 288 says you must not exceed any temporary maximum speed limit. Where you see "average speed check", your speed is measured across the whole zone, as our guide to average speed cameras in the UK explains.

What does the M25 mean for your next drive?

Let the gantries set the pace on the M25. Before you join, work out your limit for what you are driving, then keep an eye on the red circles, remember that a blank sign changes nothing, and wait for the national speed limit symbol before you pick up speed again. At Dartford, settle at 50 mph or below well before the crossing.

Ghost is a great companion for a road like this. It runs next to Google Maps and warns you safely from the background, with a banner and a tone over your music, about 700 m before a known fixed speed camera or average-speed zone. As you get closer it shows the exact distance clearly and alerts you again at 250 m, on your phone, CarPlay, Android Auto or Apple Watch. With more than 125,000 speed cameras worldwide, it is there on the M25 and wherever the road goes next.