Buying Guides · ažurirano 2026-10-16

How to Capture Number Plates with a Security Camera

Most people install a camera to see who is at the door. Then something happens on the driveway or at the farm gate, and they discover the footage shows a vehicle clearly but the number plate is an unreadable white smear. That is not a fault. A plate is a small, reflective, often fast-moving target, and a general-purpose camera is rarely set up for it.

This guide explains what actually decides whether a plate is readable, and how to set up a camera that gets it right.

Why number plates are so hard to capture

Three things work against you. First, plates are small compared with the whole scene. Second, vehicles move, which causes motion blur if the shutter is slow. Third, plates are retroreflective, meaning they bounce light straight back at its source. At night, your camera’s own infrared LEDs can turn a plate into a bright white rectangle with no visible characters.

Solving the problem means addressing all three: enough pixels on the plate, a fast enough shutter, and controlled lighting.

Start with pixels on the plate

Resolution only helps if the plate fills enough of the image. As a rough guide, aim for at least 100 to 150 pixels across the width of the plate for reliable reading. Less may still be legible to a human, but it leaves no margin for blur or compression.

Here is a simple worked example. A standard European plate is about 52 cm wide. To get roughly 130 pixels across it, you need around 250 pixels per metre of scene. A 4MP camera is about 2560 pixels wide, so it can cover a scene roughly 10 metres wide at that density. A 4K camera, around 3840 pixels wide, stretches that to roughly 15 metres.

In practice, that means you should frame tightly. A camera covering your whole front garden will not read plates. A camera aimed at the gateway or the point where cars slow down will.

Choose the right lens and distance

A wide-angle lens is ideal for general viewing but works against plate capture, because it spreads the pixels over a large area. For a plate-focused camera, a narrower field of view is better. A varifocal lens, where you can adjust the zoom during installation, is especially useful because you can fine-tune the framing rather than guess.

Keep the distance modest. For a driveway, a camera placed roughly 5 to 15 metres from where the plate passes, with a suitably narrow view, is a realistic target. Beyond that you need a longer lens or a PTZ with optical zoom, and a PTZ will not help if it is pointing elsewhere when the car arrives.

Get the angle and height right

Angle matters as much as zoom. The best view is as head-on as possible, looking along the line of travel. The more the camera sees the plate from the side, the more the characters squash together and become unreadable.

• Horizontal angle: try to keep the camera within about 30 degrees of the direction the vehicle travels.
• Height: mount it at roughly 2 to 3 metres. Too high and the downward angle distorts the plate. Too low and headlights dazzle the sensor.
• Position: choose a spot where vehicles are slow, such as a gate, a barrier, a speed bump or a tight turn.

Avoid aiming straight into the sun at dawn or dusk, and avoid pointing directly at where headlights will sweep across the lens.

Shutter speed and motion blur

A vehicle at even 20 km/h travels over five metres every second. If the camera exposes for too long, the plate blurs. Fast shutter speeds, often 1/500 of a second or quicker for moving traffic, freeze the movement, but they also make the image darker, which is why lighting is so important.

Many home cameras choose exposure automatically and offer little manual control. If your camera has shutter, exposure or night-mode settings, look for options that favour a fast shutter. If it does not, rely on placing it where vehicles move slowly. Dedicated licence plate or ANPR-style cameras are built with these controls, so check specifications carefully rather than assuming any 4K camera will do the job.

Solving night-time glare

This is where most setups fail. Infrared light bouncing off a reflective plate overexposes it. There are a few practical fixes:

1. Add external white light. Evenly lit plates let the camera use a faster shutter and lower gain, producing sharper characters.
2. Offset the camera. Mounting slightly off to one side reduces the direct reflection back into the lens.
3. Use a colour or spotlight mode instead of infrared where the camera supports it, ideally with the light aimed at the plate area and not the lens.
4. Reduce IR intensity if the camera allows it, or avoid mounting it close to a wall that bounces IR back.
5. Test after dark. A daytime test tells you almost nothing about night performance.

Recording quality and storage

Even a well-aimed camera can lose detail through heavy compression or low bitrates. Record the main stream, not the low-resolution sub-stream, for the camera watching vehicles. Use continuous or well-tuned event recording so the car is captured as it approaches, not after motion triggers. A wired PoE connection helps because it gives a stable, high-bitrate feed with no Wi-Fi dropouts. Local recording to an NVR or a quality microSD card is also useful, as it keeps full-quality footage available without relying on upload speeds.

Stay on the right side of privacy rules

Plates count as personal data in many European countries. Pointing a camera at a public road or neighbouring property can bring data protection obligations or restrictions, and rules vary by country. Frame the view to cover your own entrance and land, add signage where required, and keep footage only as long as you need it. If in doubt, check your national data protection authority’s guidance.

Conclusion

Reading number plates is about aiming a camera for a single job. Choose a narrow, ideally varifocal view, mount it two to three metres up, face it along the line of travel, and place it where cars slow down. Add white light for night-time, use a fast shutter if you can, and always test after dark before you consider it finished. If a general camera cannot manage it, a dedicated plate-capture camera is the more reliable option.