Hard Drive for CCTV Recorder: How Many TB You Need

For a CCTV recorder, use a drive built for recording 24 hours a day, then size it by three things: how many cameras you have, the bitrate each one records at, and how many days of footage you want to keep. As a rough guide, a camera recording at 4Mbps all day writes about 43GB, so four cameras kept for 14 days need around 2.5TB. The sums are below, so you can swap in your own numbers.

Surveillance drive or ordinary desktop drive?

A recorder writes video all day and night, and a drive made for a desktop computer is built for far shorter working hours. Surveillance drives are made for continuous recording. The listings for the Seagate SkyHawk and Toshiba S300 drives we sell both describe them as designed for 24/7 CCTV recording in DVR and NVR systems. Not every 3.5in SATA drive is a surveillance drive, so read the product name and description before you buy, and look for the word surveillance.

How many TB do you need?

The sum for one camera is bitrate in Mbps x 86,400 seconds in a day / 8 = megabytes per day. At 4Mbps that is 4 x 86,400 / 8 = 43,200MB, or about 43GB a day. Multiply by the number of cameras and the number of days. The table uses these assumptions: every camera records at a steady 4Mbps all day and all night, and 1TB is 1,000GB. It is an estimate only.

Your own figure will differ. A camera on a lower bitrate needs less: at 2Mbps, halve every number in the table. Recording only when motion is detected also cuts it, and a busy scene or a higher resolution pushes it up. For the exact figure, use the storage calculator built into your recorder or the one on the Hikvision website, which takes your cameras, resolution and recording settings. Then round up to the next drive size, because some space is lost to formatting.

Check what your recorder takes

Before you buy, look up the recorder's model number on the manufacturer's datasheet and read two lines: the largest drive size it supports, and how many drive bays it has. A recorder with one bay is limited to one drive, so the largest size it accepts is the limit. A recorder with two or more bays can share the load across several drives. If the datasheet gives a maximum below the size you need, shorten the retention time or lower the bitrate rather than buying a drive the recorder will not recognise.

Fitting and formatting

Switch the recorder off and unplug it. Open the case, connect the drive to the SATA data cable and the SATA power lead inside, and fix it with the screws supplied or the mounting points in the recorder. Close the case and power on. The recorder will show the drive as uninitialised, so open the storage or disk settings and format it from the recorder's menu. Formatting wipes everything on the drive, so do this on a new drive or one you no longer need. When it finishes, check that the status reads normal and that recording has started.

Which drive from our range

For most home and small business recorders, a 4TB surveillance drive is the sensible starting point. We stock the Seagate SkyHawk 4TB (5900RPM) and the Toshiba S300 4TB (5400RPM). For longer retention or more cameras there is the Seagate SkyHawk 6TB. Our NAS and enterprise drives, such as the Toshiba N300 and MG series, suit recorders and network storage that list them as supported, so check the recorder's datasheet first. Browse everything in Storage, or go straight to the 4TB, 6TB and 8TB drives.