The Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) costs $0.0353/GB while the WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) costs $0.0363/GB. Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) offers 3% better value per gigabyte as of August 2026. Both products are available on BuyPerUnit with prices from Amazon, Best Buy, and Newegg.
Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) vs WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) — Which Is Better Value?
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Specification Comparison
| Spec | Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) | WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) |
|---|---|---|
| Brand | Seagate | Western Digital |
| Capacity | 18TB | 16TB |
| $/GB | $0.0353 | $0.0363 |
| Price | $635.00 | $580.06 |
| Retailer | Newegg | Newegg |
| Category | Hard Drives (HDD) | Hard Drives (HDD) |
| Subcategory | hdd | hdd |
Price Across Retailers
Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D)
WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4)
Which Should You Buy?
Based on current pricing data, the Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) offers better value at $0.0353//GB compared to the WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) at $0.0363//GB — that's roughly 3% less per gigabyte.
The best deal for the Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) is $635.00 at Newegg, while the WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) starts at $580.06 at Newegg.
However, price per gigabyte isn't everything — consider factors like warranty, performance specs, brand reliability, and your specific capacity needs. Check each Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) and WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) product page for detailed specifications and price history.
Frequently Asked Questions
Is Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) or WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) a better deal?
As of August 2026, Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) offers better value at $0.0353//GB compared to WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) at $0.0363//GB. That is approximately 3% better value per gigabyte.
What is the price per GB of Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D)?
The Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) is currently priced at $0.0353/GB ($635.00 for 18TB) at Newegg.
Where can I buy WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) for the cheapest price?
The cheapest price for the WD Ultrastar DC HC550 16TB Hard Drive 3.5' Internal 512MB SATA 7200 RPM 512E SE NP3 DC HC550 0F38462 (WUH721816ALE6L4) is $580.06 at Newegg, which works out to $0.0363/GB.