How Much NAS Storage Do I Need?
NAS storage needs vary wildly. A Plex library with 500 movies needs 10–15 TB. A photographer archiving RAW files might need 4–8 TB. A home backup server might need 2–4 TB per computer. This page helps you estimate your actual storage requirement and find the best-priced NAS drives to fill it.
Quick capacity estimates
1 TB holds roughly: 200,000 photos (5 MB each), 500 hours of 1080p video, 170 hours of 4K video, or 15,000 hours of FLAC music. For a Plex media server, plan 1.5–3 TB per 100 movies (mix of 1080p and 4K). For computer backups, plan 1.5x your current used space per device to allow for growth. Rather run your own numbers with RAID overhead factored in? Use the interactive calculator.
Quick Verdict
- Who this is for
- First-time NAS builders and anyone upgrading their NAS who wants to buy the right amount of storage without over- or under-spending.
- What usually wins
- Start with 2x your current data plus 50% headroom for growth. For a Plex server, that usually means 8–16 TB usable. For home backups, 4–8 TB usable. Buy NAS-rated CMR drives at the best price per TB.
- Prioritise
- Calculate your usable capacity after RAID overhead. Then find the cheapest NAS-rated drives per TB at your target capacity.
Prices updated daily from Amazon.com. All links go directly to the retailer. Details.
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Interactive RAID Storage Calculator
Pick your use cases, choose a RAID level, and I'll show you the best-value drives to build it out, priced from live listings. The URL updates as you go, so you can share your setup with a link.
What are you storing?
Adjust the sliders for each use case. Leave at 0 for categories you don't need.
Redundancy / RAID
Your Storage Estimate
Move the sliders above to estimate your storage needs.
How these estimates work: Photos assume a mix of RAW + JPEG (~15 GB per 1,000 photos). 4K video assumes edited footage at ~45 GB/hour. Plex/media uses ~5 GB per movie at 1080p average. Backups assume ~500 GB per full system image. Surveillance assumes 1080p H.265 continuous recording at ~30 GB/day per camera with 30-day retention.
Usable capacity assumes one vdev of equally sized drives: mirror gives you half the drives, RAIDZ1 gives you all but one, RAIDZ2 all but two. A mirror gains nothing from an odd drive, so adding a fifth drive to four mirrored ones adds no space until a sixth joins it. Filesystem overhead takes a few percent more on top. Add 10-20% headroom for growth.
Bottom line: the lowest price-per-TB pick on this page right now is the HP 3.5-Inch 4000 GB Hot-Swap 2 MB Cache Internal Hard Drive 693687-B21, 4 TB new, at $95.18 ($23.80/TB) on Amazon.com. Check the current price.
Best Value NAS Drives
NAS-rated hard drives ranked by price per TB, the foundation of any NAS build.
HP 3.5-Inch 4000 GB Hot-Swap 2 MB Cache Internal Hard Drive 693687-B21
HGST Ultrastar He 3.5-inch 6000GB 64MB Cache 7200RPM SATA Ultra 512n Helium Platform Enterprise HDD HUS726060ALA640
WL 6TB 5700RPM 128MB Cache SATA III (6.0Gb/s) 3.5" Enterprise Datacenter Hard Drive (Server, RAID, NAS, CCTV DVR) - 1 Year Warranty
HGST Ultrastar He12 | HUH721212ALE601 | 0F27454 | 12TB 7200 RPM 256MB SATA 6.0Gb/s 3.5" Cache | 512E | BitLocker Hard Drive Encryption | Power Disable Function |
HGST Ultrastar He8 Helium 6TB 3.5-Inch 7200RPM SATA ULTRA 512e SE 128MB Cache Internal Bare or OEM Hard Drive - HUH728060ALE604 / 0F23669
Seagate ST6000NM0024 6TB 7.2K SATA 3.5" HDD
Hitachi 0F23001 6TB 7.2K 3.5" SATA 6Gbps HDD
HGST Ultrastar He6 6TB 3.5" SATA 7200 RPM Enterprise Internal Hard Drive with 64Mb Cache - HUS726060ALA640/ 0F18335 64 MB Cache 3.5-Inch Internal Bare or OEM Drives 0F18335
High-Capacity NAS Drives (12 TB+)
The largest NAS drives for maximum storage density per bay.
HGST Ultrastar He12 | HUH721212ALE601 | 0F27454 | 12TB 7200 RPM 256MB SATA 6.0Gb/s 3.5" Cache | 512E | BitLocker Hard Drive Encryption | Power Disable Function |
MDD 12TB 7200RPM SATA 6Gb/s 256MB Cache 3.5inch Internal Desktop Hard Drive, MD12TBGSA25672
MDD MAXDIGITALDATA 12TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5-inch Internal Hard Drive for Surveillance Storage (MD12TBGSA25672DVR) - 3 Years Warranty
MDD MAXDIGITALDATA 20TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5'' Internal Hard Drive (for NAS, Network Storage) - 5 Years Warranty
T2YHT 0T2YHT 12TB 7.2K 6Gb/s SATA 3.5" Hard Drive HUH721212ALE600
X16 12TB 3.5" Hard Drive ST12000NM009G 7.2K 2MT233-150 7KT9W
WD HGST 12TB HUH721212ALE601 7200RPM Ultarstar SATA 6Gb/s 256MB Hard Drive 0F29591
HP P09165-B21 Midline Helium - Hard Drive - 14 TB - Hot-Swap - 3.5 Inch Lff - SATA 6GB/S - 7200 RPM - with Low Profile Carrier
Budget NAS Drives (4–8 TB)
Affordable entry-level NAS drives for 2-bay setups and first-time builders.
HP 3.5-Inch 4000 GB Hot-Swap 2 MB Cache Internal Hard Drive 693687-B21
WD Black 4TB SATA 6.0 3.5" Desktop HDD WD4003FZEX
4TB 7200RPM SATA 3.5" Hard Drive Compatible MG04ACA400N
Toshiba MG04ACA400N - Toshiba 4TB 3.5" SATA 7.2K 6Gb/s Hard Drive
HP 4 TB 3.5" Internal Hard Drive 797267-B21
WL 4TB 64MB Cache 5400RPM SATA III (6.0Gb/s) 3.5" Internal Surveillance DVR Hard Drive - w/ 1 Year Warranty
HGST Ultrastar He 3.5-inch 6000GB 64MB Cache 7200RPM SATA Ultra 512n Helium Platform Enterprise HDD HUS726060ALA640
WL 6TB 5700RPM 128MB Cache SATA III (6.0Gb/s) 3.5" Enterprise Datacenter Hard Drive (Server, RAID, NAS, CCTV DVR) - 1 Year Warranty
How to Choose
Sizing NAS storage requires thinking about both current needs and near-term growth.
RAID overhead
RAID 1 (mirror) uses 50% of raw capacity for redundancy. RAID 5 / RAIDZ1 loses one drive worth of capacity. RAID 6 / RAIDZ2 loses two drives. A 4-drive NAS with 16 TB drives gives 48 TB raw but only 32 TB usable in RAID 5.
Media libraries
A 1080p movie averages 5–15 GB. A 4K movie averages 30–80 GB. A large Plex library with 1,000+ titles easily exceeds 20 TB. Linux ISOs and other large collections scale similarly.
Growth rate
Most users add 1–3 TB per year to their NAS. Buy 50% more capacity than you need today. It is cheaper to buy slightly larger drives now than to rebuild the array later.
Number of bays
2-bay NAS suits small deployments (RAID 1 only). 4-bay is the mainstream sweet spot (RAID 5 or RAID 10). 6–8 bays for serious media collections or multi-user setups. More bays means more flexibility for future expansion.
Frequently Asked Questions
How much NAS storage do I actually need?
Start with 2× your current data plus 50% headroom for growth. A Plex library with 500 movies at a mix of 1080p and 4K needs roughly 10–15 TB of raw storage. A home backup server covering two computers needs about 2–4 TB per machine. A photographer archiving RAW files might need 8–16 TB. This calculator page has per-use-case estimates — run your actual numbers rather than picking a round figure and hoping it fits.
How does RAID affect usable NAS capacity?
RAID adds redundancy at the cost of raw capacity. RAID 1 (mirror) uses 50% of raw storage for protection — two 8 TB drives give 8 TB usable. RAID 5 / RAIDZ1 loses one drive worth of capacity — four 8 TB drives give 24 TB usable. RAID 6 / RAIDZ2 loses two drives — four 8 TB drives give 16 TB usable. Plan your raw capacity based on the RAID level and number of bays you are configuring.
How many bays does my NAS need?
2-bay suits small deployments and RAID 1. 4-bay is the mainstream sweet spot — supports RAID 5 (good balance of capacity and redundancy) or RAID 10 (fast and redundant). 6–8 bays is for serious media collections, multi-user setups, or anyone who wants expansion room without replacing hardware. Buy more bays than you think you need; adding a bay later means buying a whole new NAS.
How fast will my NAS grow?
Most users add 1–3 TB of data per year to a NAS. A family with active cameras and a Plex library can add 3–5 TB annually. Video editors can fill that in a month. Buy at least 50% more capacity than you need today. It is cheaper to buy slightly larger drives now than to rebuild a full array later when you run out of space and prices may have changed.
Should I buy NAS-rated drives or standard desktop drives?
NAS-rated drives (IronWolf, WD Red Plus) are built for 24/7 operation, have vibration sensors for multi-bay enclosures, and use firmware tuned for always-on error recovery. For a single-drive or always-off backup NAS, standard drives work fine. For a NAS that runs continuously with 2+ drives, NAS-rated drives are worth the modest premium. Check the live $/TB rankings on this page — the gap to desktop drives is often smaller than expected.
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