Using the article’s own planning ranges, a nominal 4TB holds about 500-1,300 compressed 1080p movies, 115-267 1080p remuxes, or 40-67 4K remuxes, before system and filesystem overhead. How long 8-16TB lasts depends on the library’s current size, actual file sizes, 4K proportion and acquisition rate; estimate growth from your own library rather than assuming it will cover several years. If you're planning a serious 4K collection, budget for 20TB or more from the start. Storage is cheaper to plan for upfront than to retrofit once your NAS is full.
In short: Plan 3-8 GB per 1080p movie, 30-80 GB per 4K movie, and 1-4 GB per 1080p TV episode. Calculate household storage from the number and size of movie files and the total number and size of TV episodes; series count alone is insufficient to determine a storage requirement. For equal-sized drives, RAID 1 provides one drive’s nominal capacity from a two-drive mirror, while RAID 5 provides (N−1) drives’ nominal capacity from N drives, before system and filesystem overhead.
How Big Are Plex Media Files?
File size depends on resolution, encode quality (bitrate), codec, and duration. A 90-minute HandBrake encode has no fixed size: output depends on source complexity, codec, audio settings, and whether constant quality or a target bitrate is used. The same film as a 1080p Blu-ray remux (retaining the disc’s compressed streams without re-encoding) is 20-35 GB. At 4K, even compressed HEVC files run 20-50 GB, and 4K remuxes with Dolby Atmos or DTS:X audio routinely reach 60-100 GB each.
Plex File Size Estimates by Format
| 1080p Compressed | 1080p Remux | 4K HDR Compressed | 4K HDR Remux | |
|---|---|---|---|---|
| Typical per movie | 3-8 GB | 15-35 GB | 20-50 GB | 60-100 GB |
| Per TV episode (45 min) | 1-3 GB | 6-12 GB | 6-15 GB | 20-40 GB |
| Movies per 4TB | 500-1,300 | 115-267 | 80-200 | 40-67 |
| Best for | Most libraries | Purist 1080p collection | 4K streaming | 4K purists, archivists |
For most households, compressed 1080p (H.264 or HEVC) is the practical standard. Direct Play depends on the client’s supported container, bitrate, codecs, resolution, audio and subtitles; compatibility varies by TV and Fire TV model. 4K remuxes are for dedicated home cinema setups where maximum image quality matters and storage cost is secondary. Plex can serve both formats, but client compatibility, network bandwidth and transcoding requirements can differ in addition to storage use.
Storage Estimates by Library Size
The following estimates assume a mixed collection of 1080p compressed files with some 4K titles. Here, "usable storage" means nominal capacity after RAID overhead; actual space available for media is lower after system partitions, RAID metadata and filesystem overhead. A 2-bay NAS in RAID 1 (mirrored) uses half the total drive capacity for redundancy, so 2x 8TB drives gives 8TB usable, not 16TB.
Plex Library Size vs Usable Storage Needed
| Small Library | Mid Library | Large Library | Serious 4K | |
|---|---|---|---|---|
| Movies | 100-200 | 200-500 | 500-1,000 | 200-500 (4K) |
| TV series | 10-20 | 20-50 | 50-100+ | 20-50 (4K) |
| Illustrative storage bands | 2-5TB | 5-15TB | 15-40TB | 15-50TB |
| Suggested NAS config | 2-bay, 2x4TB | 2-bay, 2x8TB or 4-bay | 4-bay, 4x8-12TB | 4-6-bay, 8-12TB drives |
Plan for Growth
Most Plex libraries grow faster than expected. New TV seasons, rips of physical media, and higher-quality re-encodes of existing titles all consume space continuously. A rule of thumb: buy 50-100% more storage than you think you need today, and choose a NAS with enough drive bays to expand without replacing the unit. A 4-bay NAS with empty bays can provide expansion headroom, but whether it costs less overall depends on the models, drive configuration, reuse or resale value, and future pricing.
Drive costs in Australia have increased significantly from early 2025 levels. NAS-grade 4TB drives that were available for under $160 now consistently sit above $200, and larger capacities have moved proportionally. Buying more capacity now trades a higher upfront cost for additional headroom; future drive prices are uncertain, so it is not necessarily better value than expanding later. The per-TB cost of 8TB and 12TB NAS drives is typically lower than 4TB drives in the same product line, so larger-capacity drives are usually the better investment.
RAID for Plex Media Libraries
RAID (a method of spreading data across multiple drives so the system survives a drive failure without data loss) is not strictly necessary for a Plex library, but it protects against losing your entire collection to a single drive failure. RAID 1 (mirroring) on a 2-bay NAS uses two drives and provides full redundancy. If one drive fails, the other has an identical copy. You lose half your raw capacity to the mirror, but you can replace the failed drive and rebuild without data loss.
RAID 5 on a 3 or 4-bay NAS is more storage-efficient. With 4 drives you get 3 drives' worth of usable space, losing only one drive to parity. A 4-bay NAS with 4x 8TB drives in RAID 5 gives 24TB usable storage with one-drive redundancy. Synology's SHR (Synology Hybrid RAID) achieves the same protection with the added flexibility of mixing drive sizes. For media libraries, RAID 5 or SHR on a 4-bay NAS is the most practical configuration once your library exceeds 10TB.
RAID is not a backup. RAID protects against a single drive hardware failure. It does not protect against ransomware, accidental deletion, NAS unit failure, or theft. For a Plex library you care about, maintain at least one off-site or offsite backup: a second NAS, an external drive kept offsite, or a cloud backup service. RAID and backup serve different purposes and neither replaces the other.
Which Drives to Use for a Plex NAS
For a Plex media library, NAS-rated CMR (conventional magnetic recording) drives are the right choice. CMR drives write data in a straightforward track-by-track pattern; SMR drives overlap tracks and can incur read-modify-rewrite penalties when existing zones are updated. CMR is the safer general recommendation for sustained random-write and RAID-rebuild workloads, while SMR performance varies with workload. Seagate IronWolf and WD Red Plus are current NAS-rated CMR product families available from Australian retailers.
The lowest cost per terabyte varies by brand, exact SKU, retailer, stock and promotion; compare current Australian prices across several capacities before buying. The IronWolf 8TB and WD Red Plus 8TB are widely available and provide a good balance of cost, capacity, and compatibility. If you plan to grow beyond 20TB, buying 12TB or larger drives from the start means fewer drives to replace later. NAS-grade drives carry a 3-year warranty as standard; Pro and enterprise equivalents (IronWolf Pro, WD Red Pro) extend this to 5 years and are rated for higher workloads if the NAS runs 24/7 under heavy access.
Related reading: our NAS buyer's guide and our Synology vs QNAP comparison.
Free tools: Plex Media Planner and NAS Sizing Wizard. No signup required.
See also: our full Plex and Media guide.
How many movies fit on a 4TB NAS drive?
At typical 1080p compressed quality (3-8 GB per movie), a 4TB drive holds roughly 500 to 1,300 movies. At 4K compressed (20-50 GB), the same drive holds 80 to 200. At 4K remux quality (60-100 GB), you're looking at 40 to 67 movies. These estimates assume the full 4TB is available. In a RAID 1 configuration, half the capacity is used for redundancy.
How much storage for 1,000 movies on Plex?
At 1080p compressed quality, 1,000 movies need roughly 3-8TB of storage. At 4K compressed, the same library needs 20-50TB. Most households with mixed 1080p and 4K content land somewhere in between. A 4-bay NAS with 4x 8TB drives in RAID 5 (24TB usable) handles a 1,000-movie library comfortably at 1080p and partially into 4K.
How many TB do I need for a Plex server?
For a starter library of 100-200 movies and 10-20 TV series: 2-5TB usable. For a growing household library: 8-16TB usable. For a serious 4K collection: 20-50TB. Start with a NAS that has expansion headroom. A 4-bay unit populated with 2 drives lets you add drives later without buying a new device.
Should I use RAID for a Plex media library?
RAID is worthwhile if rebuilding your library from scratch would be time-consuming. RAID 1 on a 2-bay NAS or RAID 5/SHR on a 4-bay NAS protects against a single drive failure. For a library sourced from personal Blu-ray rips or purchases, the collection has real replacement cost. RAID makes sense. For libraries that can be rebuilt from other sources, RAID is optional. Remember: RAID is not a backup. Maintain a separate copy of anything you cannot afford to lose.
What is the difference between CMR and SMR drives for Plex?
CMR (conventional magnetic recording) drives write data sequentially with no overlap between tracks, delivering consistent performance under sustained read and write loads. SMR (shingled magnetic recording) drives overlap tracks for higher density but slow dramatically when rewriting existing data. Prefer CMR for RAID arrays and sustained or rebuild-heavy NAS workloads; check the manufacturer's spec sheet or product page before buying, as the recording method is not always prominently labelled.
Is Seagate IronWolf better than WD Red Plus for Plex?
Both are NAS-rated CMR product families, but performance and other specifications vary by exact model and capacity. Supported IronWolf drives can provide IronWolf Health Management diagnostics on compatible NAS models, but support depends on the exact drive SKU and NAS; Synology limits DSM support to specified pre-22-series models, and QNAP notes that not all IronWolf SKUs support IHM. Pricing varies by retailer, date and exact SKU; equal reliability between the two product families has not been established. The practical decision usually comes down to price at the time of purchase, compatibility with your NAS model's warranty terms, and availability at your preferred retailer.
How much storage does Plex itself use?
The Plex Media Server application uses very little storage. Under 1 GB for the application itself. The Plex database (metadata, thumbnails, watched status) grows with library size; The size of Plex’s server data directory-including its database, metadata, artwork and caches-varies with library contents and enabled features; video-preview thumbnails can increase it to dozens or hundreds of gigabytes. The Plex server data directory’s location varies by operating system, NAS vendor and installation configuration; budget for it separately from the media files. Some installations place the Plex server data directory on SSD-backed storage, but the supported method and location depend on the NAS platform and installation.
Can I add more storage to a NAS later?
Yes. A 4-bay NAS bought with 2 drives populated can have drives added later. Synology DSM, QNAP QTS and Asustor ADM can expand supported RAID configurations by adding or replacing drives, but eligibility and procedure depend on RAID type, NAS model, available bays and drive sizes; back up important data before changing an array. You can also replace existing drives with higher-capacity models one at a time, rebuilding the array between each replacement. This makes a multi-bay NAS with room to grow a more flexible long-term investment than a 2-bay device at full capacity.
Ready to choose a NAS for your Plex library? The Best NAS for Plex Australia guide covers every current model by tier with AU pricing and hardware transcoding support.