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.
Bottom line: the lowest price-per-TB pick on this page right now is the Avolusion HDDGEAR PRO 14TB 7200RPM USB 3.0 External Hard Drive (for Windows or MacOS, Desktop & Laptop), 14 TB new, at $299.99 ($21.43/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.
HUS726040ALS210 HGST 4TB 7.2K 12G LFF SAS Hard Drive
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
HP 857966-001 HPE 10TB SAS 12G MIDLINE 7.2K LFF
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
Avolusion HDDGEAR PRO 14TB 7200RPM USB 3.0 External Hard Drive (for Windows or MacOS, Desktop & Laptop)
MDD MAXDIGITALDATA MDD 18TB 7200RPM 256MB Cache SAS 12.0Gb/s 3.5inch Internal Enterprise Hard Drive (MDD18TSAS25672E) - [Not a SATA HDD]
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
MDD 10TB 7200RPM 256MB Cache SAS 12.0Gb/s 3.5inch Internal Enterprise Hard Drive (MDD10TSAS25672E) - [NOT A SATA HDD]
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
1PCS for 10T SAS 7.2K 3.5" Server Hard Disk ST10000NM0096
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
Avolusion PRO-H1 Series 14TB 7200RPM USB 3.2 Gen2 (10Gbps) External Hard Drive (for Windows or MacOS Desktop PC/Laptop)
HP 3.5-Inch 4000 GB Hot-Swap 2 MB Cache Internal Hard Drive 693687-B21
High-Capacity NAS Drives (12 TB+)
The largest NAS drives for maximum storage density per bay.
Avolusion HDDGEAR PRO 14TB 7200RPM USB 3.0 External Hard Drive (for Windows or MacOS, Desktop & Laptop)
MDD MAXDIGITALDATA MDD 18TB 7200RPM 256MB Cache SAS 12.0Gb/s 3.5inch Internal Enterprise Hard Drive (MDD18TSAS25672E) - [Not a SATA HDD]
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
Avolusion PRO-H1 Series 14TB 7200RPM USB 3.2 Gen2 (10Gbps) External Hard Drive (for Windows or MacOS Desktop PC/Laptop)
Avolusion PRO-T8 Series 14TB USB 3.0 External Hard Drive for WindowsOS Desktop PC/Laptop (Black) - 2 Year Warranty
BUSlink U3-20TS 20TB HDD USB 3.2 Gen 1 5Gbps/eSATA External Desktop Drive
Water Panther 16TB 7.2K RPM SAS 12Gb/s 3.5" HDD for Dell PowerEdge Servers | Enterprise Hard Drive in 14G Tray
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
Water Panther 16TB 7200 RPM SAS 12Gb/s 3.5-Inch Enterprise Hard Disk Drive in 12G 13G Tray Compatible with Dell PowerEdge Servers R730XD R730 T340 T330 T640 T630 T440
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
MDD MAXDIGITALDATA 20TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5'' Internal Hard Drive (for NAS, Network Storage) - 5 Years Warranty
Budget NAS Drives (4–8 TB)
Affordable entry-level NAS drives for 2-bay setups and first-time builders.
HUS726040ALS210 HGST 4TB 7.2K 12G LFF SAS Hard Drive
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
HP 3.5-Inch 4000 GB Hot-Swap 2 MB Cache Internal Hard Drive 693687-B21
HP 693689-S21 - 693689-B21 HP 4TB 7.2K SAS 6G DP HARD DRIVE
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
HP 693689-B21 4TB 7.2K 6G 3.5IN SAS MDL HDD - 693721-001, 695510-B21
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
Dell 202V7 4tb 3.5in 7.2k NL SAS 6gbs Hard Drive
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
IBM 4 TB 3.5" Internal Hard Drive
4TB 7200rpm 6Gbps SAS 3.5-inch Drive Compatible 342-5295
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
Western Digital Re 4TB SAS Datacenter Capacity Hard Drive 3.5 inch 7200 RPM 32MB Cache | WD4001FYYG |
SAS interface. Needs a host bus adapter, it will not plug into a normal motherboard.
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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