How do front door cameras work?

How a front door camera detects motion and starts recording

A front door camera typically uses a passive infrared (PIR) sensor to detect changes in body heat within a range of 5 to 8 metres. When the sensor picks up a heat signature that matches a person-sized object, it triggers the camera to start recording a video clip. Some models also use pixel-difference analysis, which compares successive frames of the video feed to reduce false alerts from passing cars, animals, or rustling trees (Which? video doorbell test methodology, 2026).

The recording length is typically set by the user in the phone app, ranging from 30 to 120 seconds per event. Once the clip is captured, the camera stops recording until the next motion trigger. The sensitivity of the PIR sensor can be adjusted in the app to avoid constant alerts from busy streets or low-hanging branches.

What the camera does with the video – cloud storage vs local storage

Once the camera records a clip, it sends the video over your home Wi-Fi network to either a cloud server or a local storage device. Cloud storage means the clip is uploaded to the manufacturer’s server, where you can view it from anywhere using the phone app. Free cloud plans typically store clips for 7 to 14 days, while paid plans start at £2.50 to £5 per month for longer storage and additional features (Ring Protect UK pricing, 2026; Google Nest Aware UK pricing, 2026).

Local storage saves the clips to a microSD card inside the doorbell or to a home hub unit. This option, common on brands like Eufy and Reolink, requires no monthly subscription fee. The downside is that if the doorbell is stolen or the hub is damaged, the clips are lost. A hybrid approach, where clips are stored locally but also backed up to the cloud, is available on some mid-range models.

Quick numbers – key specs for wired vs battery doorbells

How the two-way audio works and what limits it

Two-way audio works through a built-in microphone and speaker in the doorbell, which transmit your voice to the visitor and their voice back to you via the phone app. The audio is sent over the same Wi-Fi network as the video feed. Typical latency is 1 to 3 seconds, meaning there is a noticeable delay between speaking and hearing the response (Which? video doorbell audio tests, 2026).

Several factors can degrade audio quality. If the doorbell is far from the router or on a congested 2.4GHz band, the delay can increase to 5 seconds or more. Battery-powered models often reduce audio quality or mute the speaker when the battery drops below 10% to conserve power. Background noise from wind or traffic can also make conversation difficult, though some models include noise-cancellation features.

The direct answer to how do front door cameras work

A front door camera works by using a passive infrared (PIR) sensor to detect motion, then recording a short video clip (typically 30 to 120 seconds) that is sent over Wi-Fi to a cloud server or local storage, where you can view it on your phone. The camera is powered either by existing doorbell wiring (wired model) or a rechargeable battery (battery model). Two-way audio lets you speak to the visitor through the phone app, using the doorbell’s built-in microphone and speaker.

Wired models offer continuous recording and no battery charging, while battery models are easier to install but require recharging every 2 to 6 months. The choice between cloud and local storage determines whether you pay a monthly fee or keep clips on a card at home.

Compare wired vs battery video doorbell costs

How to verify your installer – MCS and other certifications

For a wired video doorbell, the installer must be registered with a Competent Person Scheme such as NICEIC or NAPIT if the work involves new wiring or a fused spur. This is required under Part P of the Building Regulations for electrical work in homes (GOV.UK – Part P building regulations, 2026). If the doorbell is connected to an existing doorbell transformer (12–24V AC), a homeowner can replace it themselves without certification.

For battery-powered models, no electrical certification is needed because the doorbell is mounted with screws and a bracket, and no wiring is involved. You can install it yourself in about 15 minutes. Always check that any electrician you hire is on the Competent Person Scheme register before work begins.

What happens when the Wi-Fi goes down – offline recording and alerts

Most battery-powered models stop recording and do not send alerts when the Wi-Fi goes down. Some wired models, such as the Ring Pro 2, can store a few seconds of video locally and upload it once the connection returns (Ring support pages, 2026; Eufy support pages, 2026). If the doorbell loses power entirely, whether from a dead battery or a tripped circuit, it will not function at all until power is restored.

If you rely on your doorbell for security, consider a model with local storage or a battery backup. A wired doorbell connected to a UPS (uninterruptible power supply) can keep recording during a power cut.

How night vision works – infrared vs colour night vision

Infrared (IR) night vision uses built-in IR LEDs, typically 2 to 6, to illuminate the area with invisible light. The camera switches to a black-and-white image mode because the sensor is more sensitive to IR light than visible light. This is the standard on most video doorbells and works well in complete darkness up to about 10 metres (Ring Battery Doorbell Plus spec sheet, 2026; Eufy S330 spec sheet, 2026).

Colour night vision uses a built-in spotlight, usually 1 to 2 LED bulbs, to provide enough visible light for a colour image. This is common on higher-end models like the Ring Pro 2 and Eufy S330. Colour images can make it easier to identify a visitor’s clothing or vehicle colour, but the spotlight may disturb neighbours or attract attention to the doorbell.

Guide to video doorbell night vision quality