NAS model specs and usable capacity
Published specifications for 48 network attached storage models, each paired with the figure the manufacturer page leaves out: how much usable capacity you actually get after parity, in both decimal terabytes and the tebibytes your operating system will report.
Researched from published manufacturer data. We do not test hardware in person.
Every model compared at 16 TB per bay
Every unit below, filled with 16 TB drives in every bay, showing raw capacity and usable capacity under single and double parity. Single parity means SHR or RAID 5, or a mirror on a two-bay. Double parity means SHR-2 or RAID 6, which needs at least four drives.
| Model | Bays | Raw TB | Single parity | Double parity | Network | SHR |
|---|---|---|---|---|---|---|
| QNAP TS-133 | 1 | 16 | none | needs 4 bays | 1 x 1GbE | No |
| Synology DS124 | 1 | 16 | none | needs 4 bays | 1 x 1GbE | Yes |
| Asustor Drivestor 2 AS1102T | 2 | 32 | 16 TB | needs 4 bays | 1 x 2.5GbE | No |
| Buffalo LinkStation 220 | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | No |
| QNAP TS-233 | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | No |
| QNAP TS-264 | 2 | 32 | 16 TB | needs 4 bays | 2 x 2.5GbE | No |
| Synology DS220+ | 2 | 32 | 16 TB | needs 4 bays | 2 x 1GbE | Yes |
| Synology DS223 | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | Yes |
| Synology DS223j | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | Yes |
| Synology DS224+ | 2 | 32 | 16 TB | needs 4 bays | 2 x 1GbE | Yes |
| Synology DS225+ | 2 | 32 | 16 TB | needs 4 bays | 2 x 2.5GbE | Yes |
| Synology DS723+ | 2 | 32 | 16 TB | needs 4 bays | 2 x 1GbE | Yes |
| TerraMaster F2-212 | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | No |
| TerraMaster F2-424 | 2 | 32 | 16 TB | needs 4 bays | 2 x 2.5GbE | No |
| TerraMaster F2-425 | 2 | 32 | 16 TB | needs 4 bays | 2 x 2.5GbE | No |
| UGREEN NASync DXP2800 | 2 | 32 | 16 TB | needs 4 bays | 1 x 2.5GbE | No |
| Western Digital My Cloud EX2 Ultra | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | No |
| Zyxel NAS326 | 2 | 32 | 16 TB | needs 4 bays | 1 x 1GbE | No |
| Asustor Drivestor 4 Pro AS3304T | 4 | 64 | 48 TB | 32 TB | 1 x 2.5GbE | No |
| Asustor Lockerstor 4 AS6704T | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | No |
| Asustor Lockerstor 4 Gen2 AS5404T | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | No |
| Asustor Lockerstor 4 Gen3 AS6804T | 4 | 64 | 48 TB | 32 TB | 1 x 10GbE | No |
| NETGEAR ReadyNAS RN424 | 4 | 64 | 48 TB | 32 TB | 2 x 1GbE | No |
| QNAP TS-464 | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | No |
| QNAP TS-473A | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | No |
| Synology DS423 | 4 | 64 | 48 TB | 32 TB | 1 x 1GbE | Yes |
| Synology DS423+ | 4 | 64 | 48 TB | 32 TB | 2 x 1GbE | Yes |
| Synology DS920+ | 4 | 64 | 48 TB | 32 TB | 2 x 1GbE | Yes |
| Synology DS923+ | 4 | 64 | 48 TB | 32 TB | 2 x 1GbE | Yes |
| Synology DS925+ | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | Yes |
| TerraMaster F4-424 | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | No |
| TerraMaster F4-424 Max | 4 | 64 | 48 TB | 32 TB | 2 x 10GbE | No |
| TerraMaster F4-424 Pro | 4 | 64 | 48 TB | 32 TB | 2 x 2.5GbE | No |
| UGREEN NASync DXP4800 | 4 | 64 | 48 TB | 32 TB | 1 x 2.5GbE | No |
| UGREEN NASync DXP4800 Plus | 4 | 64 | 48 TB | 32 TB | 2 x 10GbE | No |
| Synology DS1522+ | 5 | 80 | 64 TB | 48 TB | 4 x 1GbE | Yes |
| Asustor Lockerstor 6 AS6706T | 6 | 96 | 80 TB | 64 TB | 2 x 2.5GbE | No |
| QNAP TS-673A | 6 | 96 | 80 TB | 64 TB | 2 x 2.5GbE | No |
| QNAP TVS-h674 | 6 | 96 | 80 TB | 64 TB | 2 x 2.5GbE | No |
| Synology DS1621+ | 6 | 96 | 80 TB | 64 TB | 4 x 1GbE | Yes |
| UGREEN NASync DXP6800 Pro | 6 | 96 | 80 TB | 64 TB | 2 x 10GbE | No |
| Asustor Lockerstor 8 AS6508T | 8 | 128 | 112 TB | 96 TB | 2 x 10GbE | No |
| QNAP TS-873A | 8 | 128 | 112 TB | 96 TB | 2 x 2.5GbE | No |
| Synology DS1821+ | 8 | 128 | 112 TB | 96 TB | 4 x 1GbE | Yes |
| Synology DS1825+ | 8 | 128 | 112 TB | 96 TB | 2 x 2.5GbE | Yes |
| TerraMaster F8 SSD Plus | 8 | 128 | 112 TB | 96 TB | 1 x 10GbE | No |
| UGREEN NASync DXP8800 Plus | 8 | 128 | 112 TB | 96 TB | 2 x 10GbE | No |
| QNAP TS-h973AX | 9 | 144 | 128 TB | 112 TB | 1 x 10GbE, 1 x 2.5GbE | No |
Capacities are decimal TB, the unit printed on the drive. A 16 TB drive reports as 14.55 TiB in most NAS interfaces, which is the same bytes counted in binary. Figures are computed from bay count, not taken from vendor marketing, so they are comparable across brands.
Asustor
- Asustor Drivestor 2 AS1102T 2 bays · 1 x 2.5GbE Notable for putting a 2.5 gigabit port on an entry two-bay, which most competitors at this price still do not. Specs →
- Asustor Drivestor 4 Pro AS3304T 4 bays · 1 x 2.5GbE Four bays and 2.5GbE for close to two-bay money. The compromise is an ARM processor and fixed memory. Specs →
- Asustor Lockerstor 4 AS6704T 4 bays · 2 x 2.5GbE The four-bay that made four NVMe slots normal in this class. Otherwise a conventional N5105 unit with dual 2.5GbE. Specs →
- Asustor Lockerstor 4 Gen2 AS5404T 4 bays · 2 x 2.5GbE Four hard drive bays plus four M.2 slots, which means an eight-device array in a four-bay chassis if you want a fast tier. Specs →
- Asustor Lockerstor 4 Gen3 AS6804T 4 bays · 1 x 10GbE ECC memory, eight cores, 10 gigabit networking and four NVMe slots in a four-bay chassis. Genuinely enthusiast specification, and priced accordingly. Specs →
- Asustor Lockerstor 6 AS6706T 6 bays · 2 x 2.5GbE Six bays and four NVMe slots. Six members is the smallest count where RAID 6 stops feeling like it costs too much capacity. Specs →
- Asustor Lockerstor 8 AS6508T 8 bays · 2 x 10GbE Eight bays with two 10 gigabit ports built in, on an Atom C3538 server chip rather than a consumer processor. Specs →
QNAP
- QNAP TS-133 1 bay · 1 x 1GbE A single-bay QTS box. Like every one-bay NAS it has no redundancy, so it is a backup destination and nothing more. Specs →
- QNAP TS-233 2 bays · 1 x 1GbE QNAP entry two-bay. Mirrors two drives, runs QTS and the mobile apps, and stops there. Specs →
- QNAP TS-264 2 bays · 2 x 2.5GbE Two bays with 8 GB of memory, dual 2.5GbE and two NVMe slots. On paper the most capable two-bay in the category. Specs →
- QNAP TS-464 4 bays · 2 x 2.5GbE The four-bay QNAP most directly comparable to a DS423+, with faster networking and a PCIe slot the Synology does not have. Specs →
- QNAP TS-473A 4 bays · 2 x 2.5GbE Four bays on a Ryzen embedded chip with 64 GB of memory headroom and two PCIe slots. Built for virtual machines rather than media. Specs →
- QNAP TS-673A 6 bays · 2 x 2.5GbE The six-bay Ryzen QNAP. Six members is a good parity ratio for RAID 6, which is what you want once drives pass 10 TB each. Specs →
- QNAP TVS-h674 6 bays · 2 x 2.5GbE A desktop-class Core i3 in a six-bay chassis, shipped with QuTS hero so the filesystem is ZFS rather than ext4. Specs →
- QNAP TS-873A 8 bays · 2 x 2.5GbE Eight bays, 64 GB of memory headroom and two PCIe slots. The QNAP answer to the DS1821+, with faster stock networking and no ECC. Specs →
- QNAP TS-h973AX 9 bays · 1 x 10GbE, 1 x 2.5GbE An unusual mixed chassis: five spinning bays for bulk storage and four SSD bays for a fast tier, with 10GbE built in and ZFS underneath. Specs →
Synology
- Synology DS124 1 bay · 1 x 1GbE A single-bay DSM box. One drive means no redundancy at all, so it belongs on the network as a backup destination rather than as the only copy of anything. Specs →
- Synology DS220+ 2 bays · 2 x 1GbE · discontinued The two-bay that put Quick Sync transcoding in reach of first-time buyers. Discontinued, but common and cheap secondhand. Specs →
- Synology DS223 2 bays · 1 x 1GbE The DS223j with twice the memory and a faster USB layout. Still ARM, so still not a transcoding or virtualization box. Specs →
- Synology DS223j 2 bays · 1 x 1GbE The cheapest two-bay Synology. It mirrors two drives and runs DSM, but 1 GB of fixed memory rules out containers and heavy app use. Specs →
- Synology DS224+ 2 bays · 2 x 1GbE The first Synology two-bay with an x86 chip, which is what makes containers, virtual machines and hardware transcoding possible at all. Specs →
- Synology DS225+ 2 bays · 2 x 2.5GbE The DS224+ refreshed with 2.5 gigabit networking, which roughly doubles real transfer speed for anyone with a 2.5GbE switch or laptop adapter. Specs →
- Synology DS723+ 2 bays · 2 x 1GbE A two-bay with ECC memory, 32 GB of headroom and an expansion port. Unusual specification for the size, aimed at small business rather than media. Specs →
- Synology DS423 4 bays · 1 x 1GbE Four bays on ARM. The bay count lets SHR do something useful, but the fixed 2 GB of memory keeps this a file server rather than an application host. Specs →
- Synology DS423+ 4 bays · 2 x 1GbE The four-bay x86 Synology most households actually want: Quick Sync for transcoding, room for containers, and SHR across four drives. Specs →
- Synology DS920+ 4 bays · 2 x 1GbE · discontinued For several years the default recommendation for a home NAS, because it combined four bays, Quick Sync transcoding and DSM at a sane price. Specs →
- Synology DS923+ 4 bays · 2 x 1GbE The four-bay ECC Synology. It trades hardware transcoding for error-correcting memory and a 10GbE upgrade slot, which is the right trade for data you cannot lose. Specs →
- Synology DS925+ 4 bays · 2 x 2.5GbE The DS923+ successor: four cores instead of two, and 2.5 gigabit networking as standard. Still ECC, still no integrated graphics. Specs →
- Synology DS1522+ 5 bays · 4 x 1GbE Five bays is the awkward, useful middle: enough members that SHR-2 stops feeling wasteful, without stepping up to an eight-bay chassis. Specs →
- Synology DS1621+ 6 bays · 4 x 1GbE Six bays, ECC memory and a PCIe slot for a 10GbE card. The point where a home array stops being a two-drive mirror and becomes infrastructure. Specs →
- Synology DS1821+ 8 bays · 4 x 1GbE The classic eight-bay DSM box. Eight drives is where the drive bill dwarfs the enclosure bill, and where SHR-2 or RAID 6 stops being optional. Specs →
- Synology DS1825+ 8 bays · 2 x 2.5GbE The DS1821+ refreshed with 2.5 gigabit ports and twice the base memory. Same eight bays, same ECC, same PCIe expansion path. Specs →
TerraMaster
- TerraMaster F2-212 2 bays · 1 x 1GbE The cheapest way into a mirrored two-bay NAS from a named brand. ARM, gigabit, fixed memory, no surprises in either direction. Specs →
- TerraMaster F2-424 2 bays · 2 x 2.5GbE Two bays with an N95, 8 GB of DDR5 and two 2.5GbE ports. Hardware specification well above the two-bay norm at this price. Specs →
- TerraMaster F2-425 2 bays · 2 x 2.5GbE The current entry x86 two-bay. An x86 processor at this price is unusual, and x86 is what separates a file server from a box that can run things. Specs →
- TerraMaster F4-424 4 bays · 2 x 2.5GbE Four bays, N95, 8 GB DDR5 and dual 2.5GbE for well under what the equivalent Synology costs. The trade is software maturity. Specs →
- TerraMaster F4-424 Max 4 bays · 2 x 10GbE A four-bay with a Core i5, 32 GB of memory and dual 10 gigabit ports. Specification that normally appears two chassis sizes up. Specs →
- TerraMaster F4-424 Pro 4 bays · 2 x 2.5GbE Eight cores and 32 GB of memory as standard in a four-bay box. On paper it out-specifies every other four-bay in the category. Specs →
- TerraMaster F8 SSD Plus 8 bays · 1 x 10GbE An all-flash eight-slot NAS the size of a paperback. Silent, low power, and priced by the enclosure rather than by the storage, which is the catch. Specs →
UGREEN
- UGREEN NASync DXP2800 2 bays · 1 x 2.5GbE An Intel N100 with 8 GB of DDR5 in a two-bay chassis. The hardware is well ahead of the category price, and the software is the newest of the major vendors. Specs →
- UGREEN NASync DXP4800 4 bays · 1 x 2.5GbE The four-bay N100 model. Same processor as the DXP2800 with twice the bays, which is the cheapest route to a four-drive array with Quick Sync. Specs →
- UGREEN NASync DXP4800 Plus 4 bays · 2 x 10GbE Two 10 gigabit ports and a modern Pentium Gold in a four-bay box. Nothing else at this price ships 10GbE as standard. Specs →
- UGREEN NASync DXP6800 Pro 6 bays · 2 x 10GbE A laptop-class Core i5 with ten cores driving six bays and dual 10GbE. Processor headroom well beyond what file serving needs. Specs →
- UGREEN NASync DXP8800 Plus 8 bays · 2 x 10GbE Eight bays, four NVMe slots and dual 10GbE. On raw specification it undercuts every other eight-bay in the category. Specs →
How to read these pages
Every model page carries two things. The first is the published specification, taken from manufacturer data, with any figure we cannot verify left out rather than estimated. The second is a capacity table computed from the bay count by the same engine behind our cross-vendor RAID capacity calculator, showing usable space under every layout the box can run, at every drive size worth buying.
We deliberately do not publish a "maximum capacity" figure. Every vendor quotes that number against whatever drive was largest when their compatibility list was last revised, which means it goes stale and is not comparable between brands. Bays multiplied by drive size is the honest version, and it is arithmetic you can check.
The enclosure is the cheap part. An eight-bay build is eight drives at $200 to $500 each, so $2,000 to $4,000 in a single order, against roughly $1,300 for the box. Drives also fail and get upgraded, so that spend repeats. Read the drive comparison and how to choose NAS drives before you spend a long time choosing between two enclosures that differ by $80.
Specification alone will not tell you whether a unit suits you. A Ryzen NAS with ECC memory looks better on paper than a Celeron box and is the wrong choice if your main workload is Plex, because it has no integrated graphics for hardware transcoding. Each page says who the unit suits and, more usefully, who it does not.