Best HDD for NAS (2026): Same Capacity, Twice the Power

Most NAS drive guides sort the field by brand and tier: IronWolf or WD Red, standard or Pro. Those labels say very little about what a drive draws once it is spinning around the clock. At 12TB, the drives on this page idle anywhere from 2.8W to 6.1W by their own manufacturers’ figures — and in the comparison table below, the lowest and the highest are both sold as a WD Red Pro 12TB.

Quick picks

• Always on, 12TB, three-year warranty: WD Red Plus 12TB, model WD120EFBX. 2.9W at idle, 20 dBA idle and 29 dBA seeking.
• Always on, 12TB, five-year warranty: WD Red Pro 12TB, model WD121KFBX. 2.8W at idle, the lowest figure in the comparison table. Not WD122KFBX, which carries the same name and is listed at 6.1W.
• Always on, 8TB: WD Red Plus 8TB, model WD80EFPX. 3.4W at idle. It spins at 5,640 RPM rather than 7,200.
• 20TB and up: WD Red Pro 24TB, model WD241KFGX. 3.6W at idle — lower than either 7,200 RPM 8TB drive in the table below. Not WD240KFGX, the other Red Pro 24TB, which is listed at 3.9W.

Check the WD Red Plus 12TB on Amazon↗

Same capacity, twice the power

A hard drive does not stop drawing power when nothing is being read or written. As long as the platters are spinning, it sits at its idle figure, and a NAS that is left on and rarely busy spends most of its time there.

Each manufacturer publishes that figure on its datasheet. Put the sheets side by side and the spread within a single capacity is wide:

• 8TB: WD Red Plus (WD80EFPX) 3.4W, WD Red Pro (WD8005FFBX) 4.9W, Seagate IronWolf (ST8000VN004) 7.8W. The highest figure is 2.3 times the lowest.
• 12TB: WD Red Pro (WD121KFBX) 2.8W, WD Red Plus (WD120EFBX) 2.9W, Toshiba N300 (HDWG21CXZSTA) 4.28W, Seagate IronWolf Pro (ST12000NT001) 5.0W, Seagate IronWolf (ST12000VN0008) 5.1W, WD Red Pro (WD122KFBX) 6.1W. The highest figure is 2.2 times the lowest.

At the U.S. average residential rate of 18.31¢/kWh, each watt of continuous draw costs about $1.60 a year. A single 12TB drive therefore costs from about $4.50 a year at 2.8W to $9.80 a year at 6.1W. Across bays and years it adds up: four 12TB drives idling for three years come to about $54 at 2.8W each and $117 at 6.1W each. To use your own rate, try the power cost calculator.

What lines up with the gap

Neither brand nor tier does. In the table, Western Digital makes both the lowest 12TB figure and the highest, and sells both under the same name. At 8TB the one Pro drive is the second-lowest of three; at 12TB the three Pro drives land at 2.8W, 5.0W and 6.1W — the lowest figure, one in the middle, and the highest.

What does line up is how the drive is built. At 12TB, every helium-filled drive in the table idles at 5.1W or less, and the one air-filled drive in the table at 6.1W. At 8TB all three drives are air-filled, so fill does not separate them. The lowest of the three is also the only one at 5,640 RPM, but spindle speed is not the whole story: WD80EFZZ, another 5,640 RPM Red Plus 8TB on the same sheet, is rated at 4.1W.

That is a pattern across nine drives, not a law, and helium drives still vary among themselves: the five 12TB helium drives here run from 2.8W to 5.1W. But it is a better guide than the badge on the label, and it points at the thing that catches buyers out.

The model number is the spec

The same product name can cover more than one build.

Western Digital’s September 2025 Red Plus data sheet lists two 12TB drives. WD120EFBX is helium-filled, at 2.9W idle and 20 dBA. WD120EFGX is air-filled, at 6.1W idle and 34 dBA. Both are sold as WD Red Plus 12TB.

Its January 2025 Red Pro data sheet has the same split. WD121KFBX is helium-filled, at 2.8W idle and 20 dBA. WD122KFBX is air-filled, at 6.1W idle and 34 dBA. Both are sold as WD Red Pro 12TB, and both are in the table below.

Seagate’s IronWolf sheet has the same kind of split at 8TB. ST8000VN004, the 7,200 RPM drive in our table, idles at 7.8W; ST8000VN002, a 5,400 RPM IronWolf 8TB on the same sheet, is rated at 4.0W.

So a product name alone — “WD Red Pro 12TB”, “IronWolf 8TB” — is not enough to know which drive you are getting. Check the model number, and go by it rather than by the other specs in a listing title: one title we checked pairs the model number WD120EFBX with a 512MB cache, which Western Digital’s data sheet gives to the air-filled WD120EFGX.

Idle is not standby

When a NAS spins its drives down, they drop to their standby figure instead. Across the drives in the comparison table that publish one, standby runs from 0.3W to 1.17W; Toshiba’s sheets give an active idle figure but no standby figure for the N300.

Idle power matters in proportion to how many hours your drives actually spin. If your NAS keeps them spinning all day, it is the number to buy on. If they are parked for most of the day, it matters much less, and warranty and workload rating move up the list. The section on spinning down, further below, puts yearly figures on that.

How we compared

Every power, noise, workload and warranty figure on this page comes from the manufacturers’ own datasheets:

• WD Red Plus: data sheet dated September 2025, covering 2TB through 12TB.
• WD Red Pro: data sheet dated January 2025, covering 2TB through 26TB.
• Seagate IronWolf: datasheet DS1904.22, April 2024, which includes the 8TB and 12TB models listed here and goes up to 16TB.
• Seagate IronWolf Pro: datasheet DS2129.4, November 2023, which includes the 12TB and 24TB models mentioned here.
• Toshiba N300: specification sheets HDD-NSENE, March 2026 (the current one), and HDD-NSENA, 2024. The 20TB figures appear on both. The 12TB drive in our table, HDWG21C, is only on the 2024 sheet, so its figures come from there; on the current sheet Toshiba’s 12TB N300 is a different model, HDWG51C. Neither sheet states a warranty; the three-year warranty shown for the N300 comes from Toshiba’s N300 product page.

These are the manufacturers’ figures, not our own measurements. We have not put a meter on any of these drives. Each manufacturer measures under its own conditions — Seagate specifies its idle acoustic figure in its “Idle 1” state, and Western Digital footnotes that its power measurements are taken at room temperature — so treat a few tenths of a watt between brands as noise, and a factor of two as real.

Noise figures are each manufacturer’s own. Western Digital and Seagate publish dBA; Toshiba publishes dB (typical). None says its setup matches another’s, so on this page we compare noise within a brand, not across brands.

Running cost is idle watts × 24 hours × 365 days × years, at 18.31¢/kWh, the U.S. residential average for July 2026 from the Energy Information Administration. In the section on spinning down, the hours a drive spins each day are our assumption, not a published figure; those hours are costed at the idle figure and the rest of the day at the standby figure, at the same rate. Your own rate is on your electricity bill.

The drives

WD Red Plus 12TB (WD120EFBX)

Western Digital · $$$

VerdictWD Red Plus 12TB (WD120EFBX): the lowest idle draw in the standard tier, and the one to start from for an always-on NAS

Strengths

• 2.9W idle, the lowest of the standard-tier drives in the table
• 20 dBA idle and 29 dBA seeking, quieter under activity than WD121KFBX
• Helium-filled, 7,200 RPM

Trade-offs

• Three-year warranty and a 180TB/year workload rating
• Another WD Red Plus 12TB, WD120EFGX, idles at 6.1W — check the model number

For a two- or four-bay NAS that runs all day in a room you use, this is where to begin. Its limits are the standard tier’s limits on these datasheets: 180TB a year of rated workload, up to eight bays by Western Digital’s guidance, and three years of warranty. It is also the largest drive on Western Digital’s current Red Plus sheet, so beyond 12TB per drive you are choosing from a different line.

WD Red Pro 12TB (WD121KFBX)

Western Digital · $$$$

VerdictWD Red Pro 12TB (WD121KFBX): the lowest idle figure in the table, with the Pro warranty — if you get this model number

Strengths

• 2.8W idle, the lowest of any drive in the comparison table
• 550TB/year workload rating, five-year warranty, 2 million-hour MTBF
• Helium-filled, 20 dBA idle

Trade-offs

• 36 dBA seeking, against 29 dBA for the WD Red Plus 12TB
• WD122KFBX is also sold as WD Red Pro 12TB and is listed at 6.1W and 34 dBA idle

Against the WD Red Plus 12TB it gives up nothing at idle — 0.1W less — and adds the Pro tier’s workload rating and warranty. What it gives up is noise under activity, 36 dBA seeking against 29. The risk is ending up with WD122KFBX instead. Match the model number in the listing’s details before you buy.

WD Red Plus 8TB (WD80EFPX)

Western Digital · $$

VerdictWD Red Plus 8TB (WD80EFPX): the lowest 8TB figure, with a lower spindle speed

Strengths

• 3.4W idle, the lowest of the 8TB drives in the table
• 24 dBA idle and 28 dBA seeking, against 29 and 36 for the WD Red Pro 8TB

Trade-offs

• 5,640 RPM rather than 7,200
• Three-year warranty and a 180TB/year workload rating

It also spins slower, at 5,640 RPM against 7,200 for the other two 8TB drives in the table, and that is the trade to weigh. Western Digital’s sheet does not tie the low idle figure to the spindle speed, and another 5,640 RPM Red Plus 8TB, WD80EFZZ, is rated at 4.1W, so buy it by model number. If 8TB is the capacity you want, WD80EFPX has the lowest idle figure of the three.

Seagate IronWolf Pro 12TB (ST12000NT001)

Seagate · $$$$

VerdictSeagate IronWolf Pro 12TB (ST12000NT001): the five-year Seagate option at 12TB, with Rescue data recovery included

Strengths

• Three years of Seagate's Rescue data recovery service, which neither Western Digital sheet lists
• 550TB/year workload rating, five-year warranty, 2.5 million-hour MTBF
• Helium-filled, 20 dBA idle and 26 dBA seeking on Seagate's sheet

Trade-offs

• 5.0W idle, 2.2W more than WD121KFBX

Among the three 12TB Pro drives, this one sits between the two Western Digital builds on idle power: 2.2W above WD121KFBX and 1.1W below WD122KFBX, with the same 550TB/year rating and five-year warranty as both. What it adds over WD121KFBX is an MTBF rating of 2.5 million hours against 2 million, and Rescue. Rescue is not a Pro-only feature — Seagate’s standard IronWolf sheet lists the same three years — but neither Western Digital data sheet lists anything like it, so against WD121KFBX it is a genuine difference.

WD Red Pro 8TB (WD8005FFBX)

Western Digital · $$$

VerdictWD Red Pro 8TB (WD8005FFBX): the Pro choice at 8TB, and lower at idle than the IronWolf 8TB in the table

Strengths

• 550TB/year workload rating, five-year warranty, 2 million-hour MTBF
• 4.9W idle, 2.9W below the Seagate IronWolf 8TB in the table

Trade-offs

• 29 dBA idle and 36 dBA seeking, against 24 and 28 for the WD Red Plus 8TB
• 1.5W more at idle than the WD Red Plus 8TB

It is the only 8TB drive on this page with a five-year warranty, and at 4.9W its idle figure sits between the other two 8TB drives in the table.

WD Red Pro 24TB (WD241KFGX)

Western Digital · $$$$

VerdictWD Red Pro 24TB (WD241KFGX): three times the capacity of an 8TB drive, at a lower idle figure than two of the three 8TB drives in the table

Strengths

• 3.6W idle at 24TB
• 550TB/year workload rating, five-year warranty, 2.5 million-hour MTBF
• Helium-filled, 512MB cache, 25 dBA idle and 32 dBA seeking

Trade-offs

• 1.1W standby, against 0.3W to 0.6W for the other Western Digital drives in the tables below
• More data behind a single drive failure — plan the redundancy around that

This drive cuts against the instinct to fill every bay with smaller drives. Two of them come to 7.2W combined at idle, less than one Seagate IronWolf 8TB (ST8000VN004) at 7.8W, for six times the capacity. Seagate’s IronWolf Pro 24TB on its DS2129.4 sheet, ST24000NT002, is rated at 6.3W for one.

Western Digital’s Red Pro sheet lists a second 24TB drive, WD240KFGX, at 3.9W idle. This pick is WD241KFGX, so check the model number here too.

Seagate IronWolf 8TB (ST8000VN004)

Seagate · $$

VerdictSeagate IronWolf 8TB (ST8000VN004): reasonable if your NAS spins its drives down, costly if it does not

Strengths

• Three years of Seagate's Rescue data recovery service included
• 1.0W standby, so the gap narrows if drives are parked most of the day

Trade-offs

• 7.8W idle, the highest figure in the comparison table
• Three-year warranty and a 180TB/year workload rating

Left spinning in a four-bay NAS for three years, four of these come to about $150 in electricity at the U.S. average rate, against about $65 for four WD Red Plus 8TB (WD80EFPX). If your NAS spins its drives down, the comparison is mostly standby instead: 1.0W against 0.4W.

Compared at idle

Power, noise, workload and warranty from each manufacturer's datasheet, not our own measurements. Noise figures are each maker's own and are not directly comparable across brands. Running cost is for one drive left spinning at idle. Power cost assumes continuous operation at the U.S. average residential rate, 18.31¢/kWh (EIA, July 2026).

Model	Fill	RPM	Idle (W)	Idle noise (dB)	Workload (TB/yr)	Warranty (yrs)	3-yr power cost
WD Red Plus 8TB (WD80EFPX)Western Digital	Air	5640	3.41	24	180	3	$16
WD Red Pro 8TB (WD8005FFBX)Western Digital	Air	7200	4.92	29	550	5	$24
Seagate IronWolf 8TB (ST8000VN004)Seagate	Air	7200	7.83	28	180	3	$38
WD Red Pro 12TB (WD121KFBX)Western Digital	Helium	7200	2.84	20	550	5	$13
WD Red Plus 12TB (WD120EFBX)Western Digital	Helium	7200	2.95	20	180	3	$14
Toshiba N300 12TB (HDWG21CXZSTA)Toshiba	Helium	7200	4.286	20	180	3	$21
Seagate IronWolf Pro 12TB (ST12000NT001)Seagate	Helium	7200	5.07	20	550	5	$24
Seagate IronWolf 12TB (ST12000VN0008)Seagate	Helium	7200	5.18	28	180	3	$25
WD Red Pro 12TB (WD122KFBX)Western Digital	Air	7200	6.19	34	550	5	$29

Read the Idle column against the Fill column. Within each capacity the table runs from lowest idle figure to highest, and at 12TB the one air-filled drive in the table sits at the bottom. The top and bottom of the 12TB group are the two WD Red Pro 12TB builds, at 2.8W and 6.1W, and on Western Digital’s own sheet the air-filled one is also 14 dBA louder at idle.

The running-cost column is per drive. Multiply by the number of bays you intend to fill.

Always spinning or spun down: the yearly cost

The table above assumes drives that never stop. Many NAS systems can instead park idle drives after a set time, and a parked drive sits at its standby figure. How many hours a day your drives actually spin depends on your NAS settings and on how often something touches the disks. No datasheet can tell you that, so the figures below rest on three patterns we chose, not on any measurement:

• 24 hours spinning: the drive never parks.
• 8 hours spinning, 16 in standby: busy evenings, parked overnight and during the workday.
• 2 hours spinning, 22 in standby: a backup target or archive that wakes briefly.

Spinning hours are costed at the idle figure, not the higher read/write figure, so drives that are busy for those hours will cost somewhat more than shown. All figures are for one drive, for one year, at the same 18.31¢/kWh U.S. average used above.

Idle and standby power from each manufacturer's datasheet, not our own measurements. A dash means no published standby figure: Toshiba's N300 sheets give active idle but not standby.

Model	Capacity (TB)	Fill	Idle (W)	Standby (W)
WD Red Plus 8TB (WD80EFPX)Western Digital	8	Air	3.4	0.4
WD Red Pro 8TB (WD8005FFBX)Western Digital	8	Air	4.9	0.3
Seagate IronWolf 8TB (ST8000VN004)Seagate	8	Air	7.8	1
WD Red Pro 12TB (WD121KFBX)Western Digital	12	Helium	2.8	0.6
WD Red Plus 12TB (WD120EFBX)Western Digital	12	Helium	2.9	0.6
Toshiba N300 12TB (HDWG21CXZSTA)Toshiba	12	Helium	4.28	—
Seagate IronWolf Pro 12TB (ST12000NT001)Seagate	12	Helium	5.0	1
Seagate IronWolf 12TB (ST12000VN0008)Seagate	12	Helium	5.1	1.17
WD Red Pro 12TB (WD122KFBX)Western Digital	12	Air	6.1	0.3
Toshiba N300 20TB (HDWG62AXZSTA)Toshiba	20	Helium	4.41	—
WD Red Pro 24TB (WD241KFGX)Western Digital	24	Helium	3.6	1.1

What each pattern costs

At 8TB, the order holds at every pattern:

• WD Red Plus WD80EFPX: about $5.50 a year at 24 hours, $2.20 at 8 hours, $1.00 at 2 hours.
• WD Red Pro WD8005FFBX: about $7.90 a year at 24 hours, $2.90 at 8 hours, $1.10 at 2 hours.
• Seagate IronWolf ST8000VN004: about $12.50 a year at 24 hours, $5.20 at 8 hours, $2.50 at 2 hours.

At 12TB, the order changes:

• WD Red Pro WD121KFBX: about $4.50 a year at 24 hours, $2.10 at 8 hours, $1.30 at 2 hours.
• WD Red Plus WD120EFBX: about $4.70 a year at 24 hours, $2.20 at 8 hours, $1.30 at 2 hours.
• Seagate IronWolf Pro ST12000NT001: about $8.00 a year at 24 hours, $3.70 at 8 hours, $2.10 at 2 hours.
• Seagate IronWolf ST12000VN0008: about $8.20 a year at 24 hours, $4.00 at 8 hours, $2.40 at 2 hours.
• WD Red Pro WD122KFBX: about $9.80 a year at 24 hours, $3.60 at 8 hours, $1.30 at 2 hours.

At 20TB and up, only one drive in the table above has a standby figure:

• WD Red Pro WD241KFGX: about $5.80 a year at 24 hours, $3.10 at 8 hours, $2.10 at 2 hours.

The Toshiba N300 drives are left out of these figures. Neither Toshiba sheet publishes a standby figure for them, and we would rather leave a gap than guess one.

What changes as the hours drop

The spread shrinks. Among the five 12TB drives with a standby figure, the gap between the costliest and cheapest to run falls from about $5.30 a year at 24 hours to about $1.10 a year at 2 hours. At 8TB it falls from about $7 a year to about $1.50 a year.

The ranking can flip. WD122KFBX has the highest 12TB idle figure, but its 0.3W standby is the lowest of the five 12TB drives with a standby figure. Parked 22 hours a day, it comes out at the same yearly cost as WD121KFBX, the helium build that idles 3.3W lower. The two Seagate 12TB drives go the other way: at 1.0W and 1.17W standby, they become the costliest 12TB drives to run at both 8 and 2 hours a day. WD241KFGX moves the same way. Its 3.6W idle is below either Seagate 12TB drive, but at 1.1W standby it costs about as much as the IronWolf Pro 12TB once parked 22 hours a day.

So the number to buy on depends on how you run the NAS. If your drives stay spinning, buy on idle power. If they are parked about 22 hours a day, as in the backup-target pattern, look at standby power, and expect each drive here to cost between $1.00 and $2.50 a year. At 8 hours a day the range is $2.10 to $5.20 a year. The fewer hours they spin, the more warranty, workload rating and noise matter compared with either power figure.

Spinning down has costs that do not show up on the bill. A parked drive has to spin up before it can return a file, so the first access after a pause is slow. Each park also adds to the drive’s load/unload count, which manufacturers rate. We have not compared those ratings here, so if you set a short spin-down timer and the drives wake many times a day, look up the rating for your model.

Which one, for how you run it

Choose the tier by the warranty you want, then choose within it by idle power. The 8TB five-year and 20TB-and-up three-year cells each have a single candidate on this page.

Use case	A three-year warranty is fine	You want the five-year warranty
8TB per drive	WD Red Plus 8TB (WD80EFPX)	WD Red Pro 8TB (WD8005FFBX)
12TB per drive	WD Red Plus 12TB (WD120EFBX)	WD Red Pro 12TB (WD121KFBX)
20TB and up per drive	Toshiba N300 20TB (HDWG62AXZSTA)	WD Red Pro 24TB (WD241KFGX)

The columns separate tiers rather than budgets. Decide first whether the standard three-year warranty is enough for you. Then, within that tier, buy on idle power: workload rating and warranty are the same across the drives in each tier here, and idle power is what still differs most.

The 12TB row is where that order matters most. Within the five-year tier there are three 12TB drives on this page, at 2.8W, 5.0W and 6.1W, and two of them share a product name. Choosing by tier gets you into the right column. Only the model number gets you into the right cell.

Western Digital fills five of the six cells. Where the drives on this page give a real choice within a cell — 8TB and 12TB at three years, 12TB and 20TB-and-up at five — the lowest idle figure belongs to a Western Digital drive, and at 12TB so does the highest in the table. The 8TB five-year cell has only one candidate here. If you would rather buy Seagate, the IronWolf Pro 12TB above is the closest alternative in the five-year column.

The bottom-left pick is the Toshiba N300 20TB (HDWG62AXZSTA), rated at 4.41W idle with a 180TB/year workload rating and three years of warranty. On the datasheets cited here WD Red Plus stops at 12TB and the standard IronWolf at 16TB, so it is the only standard-tier drive at 20TB or more on this page — a default rather than the result of a comparison.

If you are deciding how many drives to buy as well as which ones, our guide to high-capacity NAS drives compares the same usable space built from two, three or four drives.

What the Pro tier is actually for

Pro drives are rated for more: 550TB a year of workload against 180TB, five years of warranty against three, an MTBF of 2 or 2.5 million hours against 1 to 1.2 million, and unlimited bays against up to eight for the standard drives on this page. 180TB a year is roughly half a terabyte a day, which a household file server is unlikely to reach and a box backing up several machines nightly may.

What the Pro tier does not buy you, on these datasheets, is lower power. The Pro drives on this page run from 2.8W to 6.3W at idle. The standard drives run from 2.9W to 7.8W. The two ranges overlap almost completely. The five-year warranty is a real reason to pay more. A smaller electricity bill is not one, unless you pick the specific model that delivers it.

If you have settled on the Pro tier and are choosing between Seagate and Western Digital, our IronWolf Pro vs WD Red Pro comparison lines the two up capacity by capacity.

Frequently asked questions

Does idle power really matter for a NAS drive?

If the drives spin all day, yes, in proportion to how many you run; the 12TB figures near the top of this page work it out. If they are parked most of the day, it matters much less, as the section on spinning down shows.

Is a helium drive always lower at idle than an air-filled one?

No. The helium drives on this page run from 2.8W to 6.3W; the air-filled ones, including WD120EFGX, from 3.4W to 7.8W. The ranges overlap. At 12TB, the one capacity here where both kinds appear, every helium drive is rated lower than both air-filled builds — but check the figure for the exact model rather than assuming.

Are any of these SMR drives?

No. Every drive on this page is listed as CMR on its manufacturer’s datasheet.

Does the WD Red Plus 8TB’s lower spindle speed explain its lower idle figure?

Not on its own: another 5,640 RPM Red Plus 8TB on the same sheet is rated higher at idle, as the WD Red Plus 8TB section above explains. If spindle speed matters to your workload, the WD Red Pro 8TB spins at 7,200 RPM.

Should I buy bigger drives and fewer of them?

For power, often yes, as the WD Red Pro 24TB section above shows. The counterweight is redundancy: fewer, larger drives means more data depends on each one, and a longer rebuild if one fails.

Why are the noise figures so different between brands?

Partly because the drives differ and partly because each manufacturer measures under its own conditions and units, as covered under How we compared. Compare noise within one datasheet, not across brands.

Where the drives go

These figures are for the drives alone; the machine they sit in adds its own idle draw on top. Our mini PC NAS comparison covers machines by how many drives they can physically hold, and the power cost calculator works out what any combined wattage costs at your own rate.