The capacity of a drive refers to the amount of data that can be stored on the drive. This is typically measured in gigabytes (GB) or terabytes (TB). The capacity depends on the type and size of the drive.
What Factors Determine Drive Capacity?
There are two main factors that determine the capacity of a drive:
- Drive Type – Hard disk drives (HDD) generally have higher capacities than solid state drives (SSD). HDDs use spinning platters while SSDs use flash memory chips.
- Drive Size – Within each drive type, larger drives have higher capacities. For example, a 3.5″ HDD has a higher capacity than a 2.5″ HDD of the same type.
Typical Capacities by Drive Type
Here are some examples of typical capacities for consumer drive types:
Hard Disk Drives (HDD)
- 2.5″ portable HDD – 500GB to 2TB
- 3.5″ desktop HDD – 1TB to 10TB
Solid State Drives (SSD)
- 2.5″ SATA SSD – 120GB to 4TB
- M.2 NVMe SSD – 250GB to 2TB
What is the Largest Consumer HDD Capacity?
Currently, the largest capacity 3.5″ desktop HDDs for consumers reach up to 20TB, like the Seagate IronWolf Pro. Enterprise and data center HDDs can go even higher, with capacities up to 24TB.
What is the Largest Consumer SSD Capacity?
For consumer SSDs, the largest 2.5″ SATA SSD capacity is currently around 8TB, like the Samsung 870 QVO. M.2 NVMe SSD capacities reach up to 4TB.
How is Drive Capacity Calculated?
Drive capacity is calculated based on the number of bytes the drive can store. Here’s how it works:
- 1 byte = 8 bits
- 1 kilobyte (KB) = 1000 bytes
- 1 megabyte (MB) = 1000 KB
- 1 gigabyte (GB) = 1000 MB
- 1 terabyte (TB) = 1000 GB
So a 1TB drive can store 1,000,000,000,000 bytes or 1 trillion bytes. Manufacturers report capacities in base 10 (eg. 1TB = 1 trillion bytes) rather than base 2 (eg. 1TB = 2^40 bytes).
What Affects Available vs Stated Capacity?
The stated capacity of a drive is never quite the same as the available capacity once it’s formatted and in use. Here’s why:
- Some space is used for formatting and file tables.
- Computers use base 2 (binary) to store data, while capacities are marketed in base 10.
- Define 1TB as 2^40 bytes instead of 1 trillion bytes results in less available capacity.
- Some space is reserved for wear leveling on SSDs.
So a “1TB” HDD might have ~930GB available capacity after formatting. Expect ~80-90% of stated capacity to be available on HDDs and ~75% on SSDs.
Factors That Can Increase Capacity
Drive manufacturers use various technologies to boost capacities within the same form factors:
- HDD – Increased areal density by using more platters and smaller/larger tracks.
- SSD – Stacked NAND chips and 3D NAND to increase density of cells.
- Newer interfaces like SATA, NVMe allow higher speeds to access more data.
- Advanced compression and deduplication features effectively increase logical capacity.
Factors That Can Limit Capacity
On the flip side, some factors can artificially limit the usable capacity:
- Older interfaces like PATA/IDE limit throughput.
- Using excessive space for RAID parity data.
- Having many small files can waste space due to minimum allocation sizes.
Ideal Capacities for Specific Uses
Here are some recommended capacities for certain use cases:
| Use Case | HDD Capacity | SSD Capacity |
|---|---|---|
| Main drive for basic computing | 500GB to 2TB | 120GB to 500GB |
| Gaming PC | 2TB to 6TB | 250GB to 1TB NVMe |
| Media storage and backups | 4TB to 10TB | 2TB to 4TB |
OS and Apps
120GB to 500GB SSDs are good for booting Windows/Linux and running applications.
Gaming
Larger 2TB+ HDDs and faster NVMe SSDs help store huge games and load them faster.
Media and Backups
Bigger 4TB+ HDDs have the capacity for media files and backup images.
External Drive Capacities
External portable hard drives usually have capacities up to 5TB for 2.5″ HDDs. Desktop external drives with 3.5″ HDDs go much higher, typically 4TB to 16TB.
Portable External HDD Capacities
- 2.5″ portable HDD – 1TB to 5TB
Desktop External HDD Capacities
- 3.5″ desktop external HDD – 4TB to 16TB
External SSD capacities range from 500GB to 8TB for SATA SSDs and up to 2TB for portable NVMe SSDs.
Network Attached Storage (NAS) Capacities
NAS systems are specialized devices designed for storage and backup. They often use arrangements of multiple HDDs for increased capacity and redundancy:
- Personal/home NAS – 4 to 32TB
- Business NAS – 32 to 256TB
Larger tower form factor NAS units support more drive bays and capacity. Rackmount NAS can scale into the petabyte range with expansion units.
Maximum Capacities of Common Drive Types
Here are the typical maximum capacities achievable with common drive types and interfaces:
| Drive Type | Interface | Max Capacity |
|---|---|---|
| 3.5″ HDD | SATA | 10TB |
| 2.5″ HDD | SATA | 5TB |
| 2.5″ SATA SSD | SATA | 8TB |
| M.2 NVMe SSD | PCIe 3.0 x4 | 4TB |
| M.2 NVMe SSD | PCIe 4.0 x4 | 8TB |
These maximums will increase over time as storage technology evolves. But for now, this table gives a good overview of current typical maximum capacities.
How Much Capacity is Enough?
Determining how much drive capacity you need depends on your storage requirements:
- OS drive – For just Windows/Linux and programs, 128GB to 500GB SSD is typically sufficient.
- Gaming PC – 1TB+ SSD and/or HDD gives room for games, media, etc.
- Media storage – A 4TB+ HDD offers ample space for photos, music, and video.
- Archival storage – Data archives may require huge 6TB+ drives.
For general use, a 500GB to 1TB SSD paired with a 2TB+ HDD works well. Beyond that look at workflow needs – video production and gaming require more storage than web browsing.
Managing and Optimizing Drive Capacity
Here are some tips for making the most of your available drive capacity:
- Regularly clear out unused files and applications.
- Use storage optimization tools built into Windows/Linux.
- Compress, deduplicate, and selectively archive data.
- Store cold data on larger slower HDDs.
- Use multiple drives for OS, apps, media and backups.
Careful organization and separation of data types helps maximize your drive capacities.
Increasing Capacity vs Buying New Drives
When your drives start getting full, you have two options:
- Add additional drives
- Upgrade to higher capacity replacements
Upgrading existing drives avoids data migration, and may provide better value at higher capacities. But adding new drives helps segment and optimize data storage, while leveraging unused capacity in existing drives.
For home users, adding a large secondary HDD or external backup drive can easily and cheaply expand total storage capacity.
New Drive Technologies That Increase Capacity
Drive manufacturers continue to develop new technologies to improve capacity:
- HAMR and MAMR HDDs – Use lasers or microwaves to write smaller magnetic bits.
- SMR HDDs – Overlapping tracks increase aerial density.
- Helium HDDs – Fill sealed drives with helium for less friction and more platters. HDD “Shingled Magnetic Recording” (SMR) layers tracks to increase density.
- Multi-actuator arms allow accessing data parallelly.
- 3D NAND SSDs stack memory cells vertically.
- QLC NAND SSDs use 4 bits per cell.
- Racetrack memory uses nanowires for ultra-dense solid state storage.
While exotic technologies take time to develop, incremental improvements gradually yield HDDs up to ~50TB and SSDs up to ~128TB within the next decade.
Conclusion
Drive capacities are determined by the type and size of drive, with HDDs reaching higher capacities than SSDs currently. Larger form factors allow for larger platters and more NAND chips. Interface standards also affect maximum potential capacities. For most home users, 500GB to 6TB offers a good capacity range for OS, apps, gaming, and media storage. Enterprise and data centers require vast multi-petabyte storage solutions. New technologies will continue pushing consumer drive capacities higher over the next decade.