Best 18TB Hard Drives by Price per TB
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Plan redundancy before capacity at 18TB, with dual parity or a backup copy, then pick a CMR NAS-class, pro NAS, or enterprise drive with the warranty you want and compare price per TB in the live ranking below.
An 18TB hard drive is what buyers reach for when a NAS is running out of bays, and what data hoarders use to consolidate a pile of smaller drives. The list below ranks today's Amazon offers for exactly 18TB — internal and external, new, renewed, and used — by price per TB, and re-ranks itself every time our price snapshot refreshes.
18TB drives are among the fastest hard drives, rated roughly 240 to 272 MB/s, and the major lines are CMR. The catch is size: writing a full 18TB at about 260 MB/s takes roughly 19 hours, so a RAID rebuild after a failure lasts most of a day. Plan for that first, then chase price per TB.
HP/Western Digital Ultrastar DC HC550 WUH721818ALE600 0F38492 18TB 7200 RPM SATA 6Gb/s 512e 512MB Cache Power Disable 3.5in Enterprise Hard Drive MB018000GXLAV P37677-001 (Renewed)
$469.00 · $26.06/TB as of Sep 26, 03:42 PM EDT
Ranks #1 at $26.06/TB — 10% below the typical 18TB HDD. Renewed condition, SATA, 3.5".
Western Digital DC HC550 18TB SATA 6Gb/s 7200RPM 3.5-inch Enterprise HDD - WUH721818ALE604 (0F38453) (Renewed)
$499.00 · $27.72/TB as of Sep 26, 03:42 PM EDT
Ranks #2 at $27.72/TB — 4% below the typical 18TB HDD. Renewed condition, SATA, 3.5".
MDD MAXDIGITALDATA 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5inch Internal Enterprise Hard Drive - 5 Years Warranty (Renewed)
$499.99 · $27.78/TB as of Sep 26, 03:42 PM EDT
Ranks #3 at $27.78/TB — 4% below the typical 18TB HDD. Renewed condition, SATA, 3.5", 5 yr warranty.
MDD MAXDIGITALDATA MDD 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5-inch Internal NAS Hard Drive (Renewed)
$499.95 · $27.78/TB as of Sep 26, 03:42 PM EDT
Ranks #4 at $27.78/TB — 4% below the typical 18TB HDD. Renewed condition, SATA, 3.5".
MDD MAXDIGITALDATA MDD (MDD18TS25672NAS) 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5'' Internal NAS Hard Drive (Renewed)
$509.99 · $28.33/TB as of Sep 26, 03:42 PM EDT
Ranks #5 at $28.33/TB — 2% below the typical 18TB HDD. Renewed condition, SATA.
Seagate Exos ST18000NM003C 18TB 7200RPM 512e SATA 6Gb/s 512MB Cache 3.5-Inch Enterprise Hard Drive (Renewed)
$529.99 · $29.44/TB as of Sep 26, 03:42 PM EDT
Ranks #6 at $29.44/TB — 2% above the typical 18TB HDD. Renewed condition, SATA, 3.5".
Seagate Exos X20 18TB 7200 RPM 512e SATA 6Gb/s 3.5" Enterprise Hard Drive - ST18000NM003D (Renewed)
$539.00 · $29.94/TB as of Sep 26, 03:42 PM EDT
Ranks #7 at $29.94/TB — 4% above the typical 18TB HDD. Renewed condition, SATA, 3.5".
Western Digital 18TB WD Red Pro NAS WD181KFGX 7200 RPM SATA 6 Gb/s CMR 256 MB Cache 3.5" Internal Hard Drive HDD (Renewed)
$539.00 · $29.94/TB as of Sep 26, 03:42 PM EDT
Ranks #8 at $29.94/TB — 4% above the typical 18TB HDD. Renewed condition, SATA, 3.5".
Seagate Exos X18 ST18000NM000J 18 TB Hard Drive - Internal - SATA (SATA/600) (Renewed)
$549.99 · $30.56/TB as of Sep 26, 03:42 PM EDT
Ranks #9 at $30.56/TB — 6% above the typical 18TB HDD. Renewed condition, SATA.
Western Digital 18TB WD Purple Surveillance Internal Hard Drive HDD - SATA 6 Gb/s, 512MB Cache, 3.5" - WD180PURZ (Renewed)
$619.00 · $34.39/TB as of Sep 26, 03:42 PM EDT
Ranks #10 at $34.39/TB — 19% above the typical 18TB HDD. Renewed condition, SATA, 3.5".
How the ranking and deal scores work
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What to look for
Redundancy matters more as drives grow. Rebuilding an 18TB drive means writing about 18TB, which takes roughly 19 hours at rated speed and longer in a busy array. With a two-drive mirror, that is a full day of heavy load on the surviving drive. Dual parity or a separate backup copy is what turns a failure at this size into an inconvenience instead of an emergency.
Check the recording method and the build. Seagate lists every current drive from 12TB to 24TB as CMR, and WD Red Pro, Purple Pro, and Ultrastar plus Toshiba N300 and MG are CMR at 18TB. Seagate's 18TB IronWolf and Exos, WD's 18TB Red Pro, and Toshiba's 18TB enterprise drive are helium-sealed. Rated speeds run from 240 MB/s on Seagate's NAS-class drive to 272 MB/s on WD's pro NAS drive.
Match the warranty to the job, and read the condition on every row. NAS-class drives carry a 3-year warranty and a 180 TB-per-year rating; pro NAS and enterprise drives get 5 years, with ratings up to 550 TB per year. Renewed drives carry the seller's warranty unless they are maker-recertified: Seagate offers 6 months and WD 1 year on recertified drives it sells directly.
FAQ
Is 18TB too big for one drive in a NAS?
It is not too big, but it raises the stakes. Rebuilding an 18TB drive takes at least about 19 hours at rated speed, and a second failure in that window can lose data in a single-parity array. Use dual parity or keep a separate backup before filling bays with 18TB drives.
Are 18TB drives helium-filled and CMR?
The major lines are. Seagate lists every current drive from 12TB to 24TB as CMR, and the datasheets for Seagate's 18TB IronWolf and Exos, WD's 18TB Red Pro, and Toshiba's 18TB enterprise drive describe helium-sealed designs. Confirm the line on the listing.
How fast is an 18TB hard drive?
Rated speeds run from 240 MB/s on Seagate's 18TB IronWolf to 272 MB/s on WD's 18TB Red Pro, with IronWolf Pro and Exos in between. Those are peak sustained ratings; average speed across the whole drive is lower because inner tracks are slower. Windows shows the drive as about 16.37 TB.
Are renewed 18TB drives worth buying?
They can be, if the warranty is clear. Amazon's Renewed Guarantee allows returns within 90 days, and Renewed Premium extends that to a year, while Seagate and WD recertified drives sold directly carry 6-month and 1-year warranties. Backblaze's data shows failure rates rise as drives age.