Home Security Camera Calculators

The genuinely calculable questions in a camera system, and every one of them maps onto something you have to buy. Each calculator shows the formula it used and says whether it rests on a published standard or an industry convention.

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• Convention

  How Many Security Cameras Do I Need?

  Work out how many security cameras a house needs from its entry points rather than its floor area, and see the recorder, storage and PoE budget that follows.

• Convention

  NVR Storage Calculator: How Many Days Will It Record?

  Calculate how many days of footage a recorder holds from your camera count, resolution, codec and drive size, and the capacity a retention target needs.

• Standard

  Bitrate to Storage Calculator

  Convert a camera bitrate in Mbps into daily, monthly and total storage, and into days of retention on a given drive.

• Standard

  PoE Power Budget Calculator

  Work out the switch power budget your cameras require under IEEE 802.3af, 802.3at and 802.3bt, and why it is larger than the cameras own draw.

• Standard

  PoE Cable Run Length Calculator

  Check whether an Ethernet run is within the ANSI/TIA-568 100 metre channel limit for a PoE camera, and what to do when it is not.

• Convention

  Security Camera Upload Bandwidth Calculator

  Calculate the upload speed and monthly data a cloud camera system consumes, and what fraction of your home uplink it takes.

• Standard

  Security Camera Lens Field of View Calculator

  Calculate the horizontal field of view of a lens and the scene width it covers at any distance, from the focal length and sensor format.

• Standard

  DORI Distance Calculator

  Calculate the distance at which a camera can detect, observe, recognise and identify a person, using the EN 62676-4 pixel per metre thresholds.

• Standard

  Camera Mounting Height and Tilt Calculator

  Calculate the down-tilt angle to frame a subject at a given distance and the dead ground directly beneath a camera at a given mounting height.

• Standard

  Night Vision and IR Range Calculator

  Check whether a subject falls within a camera published infrared range, and what pixel density the camera achieves at that distance.

• Convention

  microSD Recording Days Calculator

  Calculate how many days a microSD card records in a security camera at a given resolution, continuously or on motion only.

• Standard

  Cloud Subscription vs Local NVR Cost Calculator

  Compare the five year cost of a per-camera cloud subscription against buying a local recorder outright, and find the break-even point.

• Standard

  Camera Spacing Calculator for Perimeter Coverage

  Work out how many cameras a perimeter needs and how far apart to space them, from the lens coverage width and the overlap you want.

• Standard

  Motion Detection Zone Size Calculator

  Work out how large a person appears in frame at a given distance, which is what decides whether motion detection triggers reliably.

• Standard

  UPS Runtime Calculator for an NVR

  Calculate how long a battery backup will keep a recorder, PoE switch and router running through a power cut.