Is SD Card Faster Than HDD?

For example, the latest UFS 3.1 spec for the SD card can achieve a read speed of 2.1GB/s and a Write Speed of 1.2GB/s. This is a huge jump in its read/write performance, comparing it with most of the current card’s specifications.

If you compare HDDs with 7200 RPM which can deliver R/W speeds of 80 – 160MB/s, the UFS 3.1 SD card outperform HDD much faster.

For typical consumer usage, existing SD cards in the market are sufficiently fast to meet most of the applications. Furthermore, with its portability, lightweight and cheaper price, it has become popular among the younger and adventurer population.

U3-rated SD Card is faster than a U1-rated card, and a card with UHS Bus Interface II has a higher bus speed than UHS-I.

What Is SD Card and What Is HDD?

SD Cards

SD is an abbreviation for Secure Digital. An SD card is a type of removable memory card that is used in a wide variety of mobile and consumer electronics. It is a type of flash memory and is small, lightweight, and easy to carry around.

There are 4 different classes of SD cards: Class 2, Class 4, Class 6, and Class 10. The class refers to the minimum writing speed of the card, with Class 2 (minimum write speed is 2MB/s) being the slowest and Class 10 being the fastest (minimum write speed is 10MB/s).

Typically, SD Cards that are under 32GB are pre-formatted to FAT32, and cards that are above 32GB are formatted to exFAT or NTFS. FAT32 format tends to be slower than the exFAT/NTFS format.

NTFS file format creates a journal file whenever there is an update to the folder or file. This process provides continuity of the file system when the system fails to shut down properly. Data security is better but more writing on the disk media leads to writing wear.

SD cards also come in different sizes, with the most common being microSD cards. MicroSD cards are about the size of a fingernail and are often used in smartphones and other small devices.

SD cards can be inserted into an SD card slot or a microSD card slot. They are also available in a variety of different capacities and can go up to 2 TB.

They also come with different features such as waterproofing, X-ray proofing, and magnet proofing.

The fastest SD cards currently available in the market are UHS-II cards (Ultra High-Speed Bus Interface II). It is capable of achieving up to 312MB/s bus speed, provided the host has the same bus interface as UHS-II.


HDD’s full name is Hard Disk Drive and it was introduced in the market by IBM in 1956. It is a non-volatile electromechanical data storage device, that uses spinning disks, or platters, coated with a magnetic material to store data.

The platters are mounted on an actuator arm, which is responsible for moving the head, or read-write element, across the surface of the disk. Data is written to the disk in a series of concentric circles or tracks.

Each track is divided into a number of sectors, and each sector can store a certain amount of data. In order to read or write data to the disk, the head must be positioned over the correct track and sector.

HDDs are one of the most common types of storage devices used in computers today. They are relatively inexpensive and offer a high capacity for storing data. However, HDDs are also susceptible to physical damage and require regular maintenance in order to function properly.

The fastest HDD in the market can reach 524MB/second speeds. It can spin at 7,200 revolutions per minute (RPM), compared with most HDD speeds spinning at 5,400 RPM.

Speed Test Results

SD Card Speed Test

To test and verify your SD Card’s speed, there are a number of free tools you can use. Here are some of them you can consider:

  • AJA System Test
  • Blackmagic Disk Speed Test
  • Speed Out
  • MiniTool Partition Wizard
  • ChipGenius
  • Crystal Disk Mark

Here is the test result of 10 different SD cards (like SanDisk, Transcend, Samsung, Sony, Kingston, Toshiba, Panasonic, Verbatim, and Patriot) for you to review. Have a look and see which brand you like:

SD Cards Speed Test Results

The read speed marketed by those manufacturers ranges from 90MB/s to 95MB/s, whereas the Write Speed has a big variance from 45MB/s to 90MB/s

The actual reading and writing speed tested in the video show that in reality, all the cards perform slightly slower speed than what they advertised.

HDD Speed Test

Hard Disk Drive Test

Some free tools can be used similarly to test your Hard Disk Drive speed. For example:

  • Crystal Disk Mark
  • Blackmagic Disk Speed Test
  • AJA System Test
  • MiniTool Partition Wizard

Here is a video showing you how to do an HDD Speed test on a Seagate Hard Disk Drive:

HDD Speed Test Result

It starts with the Write Speed Test at 03:18 time, followed by the Read Speed Test at 05:28 timing.

The writing speed for different file sizes is 208MB/s, 147MB/s, and 82MB/s and the reading speed is 179MB/s, 174MB/s, and 79MB/s.

Which One Is Faster For You

HDD is faster because it has faster read and write speeds. The fastest HDD currently belongs to Seagate Exos March 2 which offers a speed of 524MB/s, whereas an SD Card with UHS-II bus interface only hit 312MB/s.

The above two cases are considered exceptionally fast speeds, but the majority of the HDDs still beat SD Cards when come to reading/writing speed.

However, certain applications or devices may suggest you use an SD Card instead of an HDD due to its advantages. Take for example a video camera, it is preferable to use an SD card as it is lighter, portable, and convenient.

For desk-bound devices, using HDD makes more sense as it gives you the capacity to process the read/write cycles faster and smoother.

Pros And Cons Of Each

HDD Pros Vs SD Card Cons

  • Offer higher capacity than SD Card
  • Provide faster read/write speed than SD Card
  • Cost per gigabyte is more advantageous than SD Card
  • offer the better capability of inputs outputs operations per second (IOPS) -> with 5400 RPM, it can offer 50~60 IOPS
  • it is more reliable than SD Card, does not fail as often as SD Card
  • data can store longer than SD Card
  • no write numbers limitation like SD Card due to its flash memory structure

HDD Cons Vs SD Card Pros

  • More expensive than SD Card
  • Bulkier and heavier than SD Card
  • are fragile and need the care to handle the HDDs
  • need an external power source to power the HDD

Final Thoughts

Before you make a decision to choose which disk media to use, look at your particular device and application. Compare the advantages and disadvantages of each usage, and select the best media for your need.

Electronic technology is evolving very rapidly each year, and many devices are using it to power the next generation of devices. We predict that SD cards will become the mainstream media in most of the applications we encounter in the future.

Do look out for the next generation of SD cards, it will surprise you with its capabilities.

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