Learn about the differences between HDDs and SSDs, the form factors available, how they compare in capacity, speed, power, and more.
Choosing the right storage isn’t just about comparing capacity and cost. The type of storage your computer uses matters for performance, including power usage and reliability. Solid state drives (SSDs) and hard disk drives (HDDs) are the two main storage options to consider and it’s important to know the best use for each and how they compare side by side.
What is an HDD?
An HDD is a data storage device that lives inside the computer. It has spinning disks inside where data is stored magnetically. The HDD has an arm with several "heads" (transducers) that read and write data on the disk. It is similar to how a turntable record player works, with an LP record (hard disk) and a needle on an arm (transducers). The arm moves the heads across the surface of the disk to access different data.
HDDs are considered a legacy technology, meaning they’ve been around longer than SSDs. In general, they are lower in cost and are practical for storing years of photos and videos or business files. They are available in two common form factors: 2.5 inch (commonly used in laptops) and 3.5 inch (desktop computers).
What is an SSD?
SSDs got their name—solid state—because they have no moving parts. In an SSD, all data is stored in integrated circuits. This difference from HDDs has a lot of implications, especially in size and performance. Without the need for a spinning disk, SSDs can go down to the shape and size of a stick of gum (what’s known as the M.2 form factor) or even as small as a postage stamp. Their capacity—or how much data they can hold—varies, making them flexible for smaller devices, such as slim laptops, convertibles, or 2 in 1s. And SSDs dramatically reduce access time since users don’t have to wait for platter rotation to start up.
SSDs are more expensive than HDDs per amount of storage (in gigabytes, or GB, and terabytes, or TB), but the gap is closing as SSD prices begin to drop.
SSD vs. HDD: Speed
What makes SSDs an increasingly popular choice is their speed. Across the board, SSDs outpace HDDs because they use electrical circuitry and have no physical moving parts. This leads to shorter wait times when you’re starting up and fewer delays when opening apps or doing heavy computing tasks. A typical SSD from Intel with a middle-of-the-road 512 GB capacity (Intel® SSD 760p Series) offers up to 10x faster read speeds and up to 20x faster write speeds than a midrange HDD (such as Seagate 2 TB Barracuda* 5400 RPM 128 MB Cache SATA* 6.0 Gb/s 2.5" laptop internal hard drive ST2000LM015), which only offers data transfer speeds of up to 140 MB/s.
These faster speeds lead to performance benefits in several areas, such as when logging in and waiting for apps and services to start up, or when performing storage-intensive tasks such as copying a large file. With an HDD, performance slows significantly, while an SSD can continue to work on other tasks.
Speed is also influenced by the interface used in an SSD vs. hard drive that connects to the rest of the computer system when transferring data back and forth. You might have heard of these interfaces—SATA and PCI Express* (PCIe*). SATA is an older, slower, legacy technology, while PCIe is newer and faster. SSDs with PCIe* interfaces will typically be much, much faster than HDDs with SATA.
Although no one ever complains that their computer is too fast, there are times when an HDD can make sense. If you have terabytes of files that you want to store, HDDs are still a less expensive option, although that’s changing with increasingly lower SSD prices. Computer storage decisions can be simplified by thinking of data as either cold or hot. "Cold" data might include the years of photos you want to keep on your laptop but don’t look at every day and don’t need quick access to. HDDs can be an excellent, cost-effective choice for cold data. At the other end of the spectrum, if you’re a business running real-time transactions, editing videos and photos and need fast access to database files, video clips, or models, or even just running the operating system, that’s what we refer to as "hot" data. The fast performance of SSDs makes them an ideal choice for those efforts where speedy access to your data is what matters most.
Head-to-head comparison: SSD vs. HDD
When it comes to capacity, SSDs for computers are available in 120 GB to 4 TB capacities, whereas HDDs can go anywhere from 250 GB to 14 TB. When measuring cost per capacity, HDDs come out on top, but as SSDs drop in price, this will become less of a differentiator for HDDs.
Reliability is defined as whether data is stored as intended, in an uncorrupted state. SSDs in general are more reliable than HDDs, which again is a function of having no moving parts. That’s because without movement, SSDs aren’t affected by vibration or related thermal issues.
SSDs commonly use less power and result in longer battery life because data access is much faster and the device is idle more often. With their spinning disks, HDDs require more power when they start up than SSDs.
The gaming experience: SSD vs. HDD
Gamers need a computer drive that accesses data quickly, which makes SSDs optimal for the best gaming experience. Video games contain enormous amounts of assets, such as high-resolution textures, models, audio, and more—up to 100 GB of data, in some cases. These requirements make speed and capacity paramount. A game that that takes two to three minutes to load on an HDD takes well under a minute on an SSD. And the initial load is not the only time a game needs to access stored data. Data is needed whenever the player enters a new level, scene, or mission. Long load times can disrupt the game and fast load times protect the sense of immersion that you want when in the middle of your game. If you need help choosing the right SSD for your gaming needs, read about the best SSD for gaming.
Data is the center of so much that we do. When choosing between an SSD or an HDD, there are numerous considerations beyond storage capacity and cost. Reliability, speed, noise, and power usage all come into play, affecting your overall experience. When you identify the type of data that you are working with and how and when you need to access it, you can compare a solid state drive vs. hard drive to find the solution that’s right for you.