The smallest outlay that fills all 4 bays is $442.36 (4 x 2TB). Buying for best value per terabyte instead costs $1999.96 (4 x 20TB) and buys far more storage. Recertified stock fills it for $239.96 at 3TB a drive - a smaller build, not a bigger discount. The chassis adds $649.99 if you do not already own one. Every basket below is priced per line so you can see where the money goes.
Live prices updated · 4 bays · TOS 6
The price of a NAS is the number on the box, and it is the smaller half of what you spend. A 4-bay chassis is an empty frame: the drives that make it storage cost more than the machine at almost every capacity worth buying, and nobody publishes that combined figure because it needs a live drive catalogue and a bay count in the same place.
That is what this page is. Three tiers, each priced from listings that are in stock at the moment you loaded it, multiplied by this model's 4 bays, with the usable capacity you actually end up with after parity. The tiers are not better and worse versions of the same thing - they are three genuinely different purchases, and which one is right depends on what the array is for.
The smallest bill that fills this machine is 4 x 2TB at $110.59 each - $442.36 for 8TB raw. The best cost per terabyte is a much larger drive, so it costs more in total and gives you several times the capacity. Optimising per-terabyte value always selects the biggest drive available; if your budget is the constraint rather than your capacity need, the smaller drive is the right answer and we would rather name both than let one label imply the other.
Lowest cost per terabyte among new, in-stock, CMR-verified drives - the most storage per dollar, not the smallest bill.
Cheapest qualifying listing right now: MDD 20TB SATA 7200RPM NAS at $499.99 each ($25.00/TB), CMR, SATA-6G. 4 x $499.99 = $1999.96 for a full set.
| RAID level | Usable TB | Cost per usable TB |
|---|---|---|
| RAID 1 | 20TB | $100.00 |
| RAID 5 | 60TB | $33.33 |
| RAID 6 | 40TB | $50.00 |
| RAID 10 | 40TB | $50.00 |
4 items across 1 listing. In-stock listings only. Anything out of stock when this page loaded is named below rather than silently dropped.
| Item | Qty | Each | Line | |
|---|---|---|---|---|
| DriveMDD 20TB SATA 7200RPM NAS (20TB) | x4 | $499.99 | $1999.96 | Buy |
| Basket total | $1999.96 | |||
Left out because it is not in stock right now: TerraMaster F4-425 Plus 4-Bay.
These are our current tracked prices. Amazon sets the seller and the final price at checkout - verify before you buy. Opening any item starts an Amazon session, and anything you add there is part of the same order - you do not need to come back here between items.
Nearline-class drives - Exos, Ultrastar, Toshiba MG, IronWolf Pro, WD Red Pro - built for continuous duty.
Cheapest qualifying listing right now: WD Ultrastar 12TB SATA HUH721212ALE601 at $339.99 each ($28.33/TB), CMR, SATA-6G. 4 x $339.99 = $1359.96 for a full set.
| RAID level | Usable TB | Cost per usable TB |
|---|---|---|
| RAID 1 | 12TB | $113.33 |
| RAID 5 | 36TB | $37.78 |
| RAID 6 | 24TB | $56.67 |
| RAID 10 | 24TB | $56.67 |
4 items across 1 listing. In-stock listings only. Anything out of stock when this page loaded is named below rather than silently dropped.
| Item | Qty | Each | Line | |
|---|---|---|---|---|
| DriveWD Ultrastar 12TB SATA HUH721212ALE601 (12TB) | x4 | $339.99 | $1359.96 | Buy |
| Basket total | $1359.96 | |||
Left out because it is not in stock right now: TerraMaster F4-425 Plus 4-Bay.
These are our current tracked prices. Amazon sets the seller and the final price at checkout - verify before you buy. Opening any item starts an Amazon session, and anything you add there is part of the same order - you do not need to come back here between items.
Recertified and used enterprise stock, the cheapest terabyte in the catalogue at most capacities.
Cheapest qualifying listing right now: HGST HUS724030ALA640 3TB SATA Enterprise at $59.99 each ($20.00/TB), CMR, SATA-6G. 4 x $59.99 = $239.96 for a full set.
| RAID level | Usable TB | Cost per usable TB |
|---|---|---|
| RAID 1 | 3TB | $79.99 |
| RAID 5 | 9TB | $26.66 |
| RAID 6 | 6TB | $39.99 |
| RAID 10 | 6TB | $39.99 |
Recertified stock; verify SMART on arrival. 4 items across 1 listing. In-stock listings only. Anything out of stock when this page loaded is named below rather than silently dropped.
| Item | Qty | Each | Line | |
|---|---|---|---|---|
| DriveHGST HUS724030ALA640 3TB SATA Enterprise (3TB) | x4 | $59.99 | $239.96 | Buy |
| Basket total | $239.96 | |||
Left out because it is not in stock right now: TerraMaster F4-425 Plus 4-Bay.
These are our current tracked prices. Amazon sets the seller and the final price at checkout - verify before you buy. Opening any item starts an Amazon session, and anything you add there is part of the same order - you do not need to come back here between items.
Every drive above is CMR-verified. Shingled (SMR) drives overlap their tracks to gain density, which makes rewriting slow in a way that shows up precisely when you least want it: during a RAID rebuild, when the array is already degraded and running without its safety margin. Rebuilds that should take a day have taken over a week on SMR drives, and some controllers drop the drive out of the array entirely.
We also exclude drives whose recording technology we could not confirm, rather than assuming them safe - the CMR/SMR list shows which models are which and how each one was verified.
Our picks are matched on interface and form factor to this chassis and verified CMR. That is our method and it is the whole of our claim. TerraMaster publishes its own compatibility list, and where a vendor does, that list is the authority on what they have tested - it is not a list of what physically works, which is usually much larger. If you are buying for a warranty claim or a supported deployment, check the vendor list. If you are building storage, the interface, the form factor and the recording technology are what determine whether a drive works.
We have no documented memory-expansion figure for this model, so we do not print one. Check the manufacturer's specification before buying memory for it.
This model is specified at an unstated network speed. A filled array can move data faster than a single gigabit link carries it, so the network is worth checking before you blame the drives. 10GbE switches and cards, priced.
One thing we will not sell you: an uninterruptible power supply. A NAS writing parity when the power fails can corrupt an array, and a UPS that gives the machine sixty seconds to shut down cleanly is the cheapest insurance in the build. We do not track UPS prices, so treat that as advice rather than a recommendation of any particular unit.
Fill costs for every NAS we track · F4-425 Plus 4-Bay listing and specs · NAS drives · NAS builder · RAID usable capacity calculator · Recertified drives
Between $1999.96 and $1999.96 for all 4 bays, depending on the tier you choose, at the prices we track right now. The cheapest tier uses the lowest cost per terabyte among new CMR-verified drives that fit; the enterprise tier uses nearline drives built for continuous duty; the refurbished tier uses recertified enterprise stock. Those totals are drives only - the chassis is priced separately in each basket above, because plenty of people filling a NAS already own the box.
Physically yes, usefully no - in standard RAID. RAID 1, 5, 6 and 10 all size themselves to the SMALLEST drive in the array, so a 20TB drive beside three 8TB drives contributes 8TB and wastes 12. Synology's SHR and UnRAID are the exceptions: both are designed to use mixed sizes and will recover most of that difference. If you are buying all 4 drives at once, buy them the same size. If you are growing an existing array on standard RAID, understand that capacity only increases once every drive has been replaced.
Both are defensible and the honest answer depends on redundancy. Refurbished enterprise drives are the cheapest terabyte in our catalogue at most capacities, and RAID is exactly where their higher early-life failure risk is absorbed - that is what parity is for. The trade is a reseller warranty rather than a manufacturer one, and the requirement that you actually check SMART on arrival. In a 4-bay box running dual parity, refurbished is a rational choice. In a two-bay mirror holding the only copy of something, buy new.
Our picks are matched on interface and form factor and are CMR-verified - we exclude shingled drives and, deliberately, drives whose recording technology we could not confirm. That is our method, not the manufacturer's blessing. Where the maker publishes its own compatibility list, that list is the authority and we link it rather than paraphrasing it. Most NAS vendors support far more drives than their lists name; the lists tell you what they tested, not what works.
Only if you do not already have one. Each basket above shows the chassis as its own line so you can see the whole build cost, and you can simply not buy that line. We show it because "what does this NAS cost, filled" is the question people actually have, and answering it with drives alone understates the number by several hundred dollars.
Because parity costs drives, not percentages. RAID 5 gives up one drive's worth of capacity, RAID 6 gives up two, and RAID 10 gives up half. On a 4-bay machine that is a large fraction, which is why the tables above show usable terabytes and cost per usable terabyte rather than only the raw sum. Cost per usable terabyte is the number that actually compares two builds.