Free browser-based calculator
Media Storage Calculator
Turn video and audio bitrate into storage per hour, total library size, backup capacity and estimated hours per drive.
The calculation in plain English
Total bitrate is converted from bits per second to decimal gigabytes per hour, then multiplied by runtime and your overhead allowance. The math is straightforward: Mbps times 3600 seconds in an hour, divided by 8 bits per byte and 1000 megabytes per gigabyte. Audio bitrate is entered in kbps so it gets divided by 1000 first.
“Total copies” includes the primary copy. Choose 1 for no backup (zero-protection), 2 for one working copy plus one full backup, 3 if you keep a cold copy off-site, and so on. Most home lab media libraries run with two copies; the third copy is cheap insurance against a single backup failing silently.
Why bitrate beats resolution as a planning number
Two files both labeled 4K can differ by several times in size because codec, encoder settings, frame rate, HDR metadata and source quality all matter. A well-encoded HEVC 4K stream at 15 Mbps fits in half the space of an older H.264 4K at 40 Mbps. Use MediaInfo or your server’s file details panel to sample actual bitrates instead of relying on the preset labels.
Variable-bitrate media can move well above or below its average during action scenes, fast pans or grain-heavy shots. Thumbnails, preview clips, subtitles, artwork, database files and any transcoded versions you keep locally require additional space that this calculator intentionally excludes — it is planning the raw media, not the whole Jellyfin or Plex directory tree.
How much overhead should you reserve?
The metadata and filesystem overhead field covers everything that is not the encoded media itself. For ZFS with LZ4 compression and a single pool, 3-5% is usually enough. For older ReFS or NTFS pools containing many small subtitle and NFO files, 5-8% is safer. If you plan to keep artwork, chapter thumbnails and movie poster cache inside the same directory, bump it to 10%. When in doubt, sample your existing library: total the sizes of all non-video files and divide by total library size.
Capacity is not backup
RAID or ZFS redundancy can keep a pool online after a disk failure, but it does not protect against deletion, corruption, ransomware, theft or a damaged enclosure. Use the RAID and ZFS calculator for usable pool size, then plan at least one independent copy — ideally on physically separate hardware that you detach after the backup job completes.
How does this tie into transcoding?
A library of 500 hours at 20 Mbps is about 4.5TB per copy, but if your server needs to transcode multiple 4K streams simultaneously you also need CPU that can keep up. Our measured Jellyfin QSV tests show what the Core i3-1215U in a typical mini PC can handle in real workloads, and our hardware-transcoding setup guide walks through the configuration so your server does not fall back to software encoding at the worst moment.
One last sanity check
After the calculator gives you a per-drive recommendation, divide your target usable capacity by the drive count to see whether the recommended raw capacity per disk makes sense for the drives you can actually buy. If the math calls for 4×12TB but 12TB drives are out of budget, run the numbers again with 4×10TB and a slightly shorter planning horizon — the library will still grow, just not as far into the future.