The best 4-bay NAS today is the TerraMaster F4-425 4-Bay at $365.49 ($91.37/bay), as of 2026-10-01.
Recomputed every refresh · last updated · 10 listings in the field
The TerraMaster F4-425 4-Bay takes it at $91.37/bay against the runner-up's $100.00/bay - a margin of $8.63/bay, or 9.4%. That gap is computed, not asserted: it is the arithmetic difference between the two cheapest qualifying listings we hold, and it is the whole of the reason one is above the other.
It sits in a field of 10 qualifying listings. It is new stock.
Best = lowest price per bay among in-stock, new 4-bay NAS units from known NAS makers, chassis only. All-flash units are excluded because their bays are M.2 slots. No listing we hold includes drives; each row says whether its own title states "Diskless". Not a performance ranking: processor, memory, network, noise and power draw are not measured and not ranked.
Most "best drive" pages do not tell you what best meant, which makes them impossible to argue with and therefore impossible to trust. Ours is one sentence and you can reject it: if you would rather optimise for warranty length, for a specific manufacturer, or for the lowest absolute price rather than the lowest price per unit, the full field is ranked below and you can take a different row knowing exactly what you are trading.
What the criterion deliberately excludes: all-flash units (their bays are M.2 slots), makers we do not recognise, used units, and anything out of stock at the moment the page rendered. SAS drives are excluded here because they need a host bus adapter and a backplane that a desktop or consumer NAS does not have.
| # | NAS | Bays | Note | Price | Per bay | Buy/View Price |
|---|---|---|---|---|---|---|
| WINNER | TerraMaster F4-425 4-Bay | 4-bay | Diskless (title says so) | $365.49 | $91.37 | Buy/View Price |
| 2 | Synology DiskStation DS423 4-Bay Diskless | 4-bay | Diskless (title says so) | $399.99 | $100.00 | Buy/View Price |
| 3 | Synology DiskStation DS425+ 4-Bay Diskless | 4-bay | Diskless (title says so) | $599.99 | $150.00 | Buy/View Price |
| 4 | QNAP TS-464-8G 4-Bay | 4-bay | Drives not stated in title | $639.00 | $159.75 | Buy/View Price |
| 5 | TerraMaster F4-425 Plus 4-Bay | 4-bay | Diskless (title says so) | $649.99 | $162.50 | Buy/View Price |
Tracking has just started for this page, so there is no change history yet. We will not invent one: the log fills when the winner actually changes hands, and until then the honest statement is that we began watching and nothing has moved. That emptiness is temporary and it is the reason this page will be worth more in three months than it is today.
The most common NAS buyer: a household or small office that wants more than a mirror - RAID 5 or SHR across four drives, room to grow, and a single failed drive survived.
Four bays is where parity becomes worth it: one drive's worth of protection spread over four. It is also where the market is deepest, so the cost-per-bay field is the widest of any bay count we rank.
Worth knowing: The cheapest four-bay box per bay and the right one are not always the same purchase. Processor, memory and network speed differ widely across this field and none of them is in the ranking, so read the specification column of the listing for anything you need - transcoding, 10GbE, memory you can upgrade.
The 10 qualifying listings run from $91.37/bay to $200.00/bay, a spread of $108.63/bay between the cheapest and dearest drive that meets the same standard. That spread is worth looking at before you act on the verdict: a tight field means the market has settled and the winner is a few percent ahead of an equivalent product, while a wide one means the drives differ in something the criterion does not capture - usually product line, warranty term or how long the listing has been sitting.
5 brands are represented. More than one manufacturer competing at the same specification is what makes the cheapest listing meaningful rather than incidental.
The median listing in this field sits at $164.25/bay, 80% above the winner. Every drive in this field is the same capacity, so the per-terabyte ranking and the price ranking are the same ranking - the cheapest drive is the winner by definition.
Cost per bay is the chassis price divided by the number of drive slots. It makes boxes of different sizes comparable before any drives are bought, and it is the honest basis for this page because it is something we can compute for every listing we hold.
It is a chassis-only figure. Every NAS listing we read on 1 October 2026 either said 'Diskless' in its title or said nothing about drives; none included them. Each row says which, so a diskless box and one whose listing is silent are never presented as the same purchase.
What it does not include is most of what makes one NAS better than another: processor, memory, network speed, operating system, noise and power draw. We measure none of them, so none is in the ranking. For those, the maker's specification and our NAS device pages are the place to look.
The larger cost of a NAS is usually the drives. Our fill pages price a full box of drives at each bay count, which is the comparison to make before choosing a box on chassis price alone.
It is a price-and-fitness answer and nothing more. We do not run a test lab, we publish no read or write figures, and there is no claim anywhere on this page that one drive is faster than another. Ranking storage by speed requires measuring it, and anyone who does should tell you how; we would rather rank on what a catalogue can actually observe every few hours.
It also cannot tell you how a manufacturer handles a warranty claim, how loud a drive is in a room you sit in, or whether a particular batch had a bad year. Those are the things a review is for. What this page does that a review cannot is stay correct: it is recomputed when you load it, and the field it beat is printed underneath so you can see the answer being earned rather than asserted.
This page gives one answer. If you want the full catalogue rather than a verdict, these are the pages that carry it:
Every NAS we track · What it costs to fill a NAS · Best NAS drive · Every verdict we publish · Where prices are heading · CMR/SMR list
Today's cheapest is not a reason to buy today. This answer is recomputed from live prices, so it will change - sometimes in your favour. Buy when you need the capacity, not because a page named a winner, and read the criterion above: it ranks what we can measure, which is price and fitness, not everything that matters to you.
TerraMaster F4-425 4-Bay, at $365.49 ($91.37/bay). That is the lowest cost per bay among the 10 listings that meet this page's criteria. It is a price-and-fitness verdict rather than a performance ranking.
We log the winner every time it changes and show the last three above. This page has only just started tracking, so there is nothing to show yet - and we would rather say that than imply a history we do not have. Check back and the log will fill itself.
Because the criterion is cost per bay, not brand reputation, and it is printed on this page precisely so you can disagree with it. Every drive in the field passes a brand gate - we will not name an unrecognised seller as an answer - but among drives that pass, the cheapest bay wins. If you value a specific manufacturer's warranty handling or a particular product line, the full field below is ranked and you can pick a different row with the trade-off visible.
No, and this is the most important limitation on the page. We do not benchmark drives, we do not publish read or write figures, and nothing here claims one drive is faster than another. What we can measure is price, availability, capacity, interface and recording technology, so the verdict is built from those. Anyone ranking drives by speed should tell you how they measured; we would rather rank on what we can actually observe.
How much weight the verdict carries. 10 listings meet the criteria right now. That is a deep field: several sellers are competing and the winner earned it against real alternatives.