The Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) costs $0.0361/GB while the SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive costs $0.0681/GB. Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) offers 47% 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 SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive — Which Is Better Value?
Prices refresh twice daily; the final price appears at the retailer's checkout. We may earn a commission from retailer links, at no cost to you; it never affects rankings.
Specification Comparison
| Spec | Seagate Exos X20 ST18000NM003D 18TB 7200 RPM 256MB Cache SATA 6.0Gb/s 3.5' Internal Hard Drive (ST18000NM003D) | SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive |
|---|---|---|
| Brand | Seagate | SanDisk |
| Capacity | 18TB | 18TB |
| $/GB | $0.0361 | $0.0681 |
| Price | $650.00 | $1224.99 |
| Retailer | Newegg | Newegg |
| Category | Hard Drives (HDD) | Hard Drives (HDD) |
| Subcategory | hdd | hdd |
Price Across Retailers
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 $0.0361//GB compared to the SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive at $0.0681//GB — that's roughly 47% 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 $650.00 at Newegg, while the SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive starts at $1224.99 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 SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive 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 SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive 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 $0.0361//GB compared to SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive at $0.0681//GB. That is approximately 47% 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 $0.0361/GB ($650.00 for 18TB) at Newegg.
Where can I buy SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive for the cheapest price?
The cheapest price for the SanDisk Professional 18TB G-DRIVE PROJECT Thunderbolt 3 External Hard Drive is $1224.99 at Newegg, which works out to $0.0681/GB.