NVR Hard Drive Calculator

Estimate how much usable storage a multi-camera NVR needs, then round up to a practical surveillance-drive size.

Duty cycle: use it carefully

Continuous recording uses a 100% duty cycle. Motion-only recording can reduce stored footage, but the actual percentage depends on the scene. A driveway with trees, insects and traffic can record far more than a quiet interior room. When evidence is important, underestimating motion activity is worse than buying extra storage.

Why the calculator adds headroom

Drive marketing capacity, filesystem overhead, metadata, audio, variable bitrate and future expansion all reduce the usefulness of an exact theoretical calculation. A 20% planning margin is a reasonable starting point, but larger systems often benefit from more.

One large drive or several?

Your NVR determines how many bays and what maximum drive sizes are supported. This calculator estimates total usable capacity; it does not choose a RAID layout. Verify recorder bay count, supported drive capacity and surveillance-drive compatibility before purchasing.

Related: how long 1TB lasts and H.264 vs H.265 storage.