What is compact flash card Type 1 and 2?

CompactFlash (CF) is a flash memory mass storage device used mainly in portable electronic devices. The format was specified and the devices were first manufactured by SanDisk in 1994 (1). CompactFlash cards were originally designed as a miniature version of the PC Card storage format used in laptop computers at the time.

CompactFlash became popular in the late 1990s for storage expansion in early digital cameras, video camcorders, and personal digital assistants. It offered greater capacity compared to other storage formats available at the time. CompactFlash remained widely used for professional photography and videography through the early 2000s (2).

Today, CompactFlash has largely been superseded by smaller, faster formats like SD cards in consumer devices. However, CompactFlash still maintains some popularity in industrial, military and other applications that require ruggedness, high capacity storage, or backwards compatibility. Overall, CompactFlash played an important role in the transition from film to digital photography and expanding storage capacities in early portable electronics (3).


(1) https://en.wikipedia.org/wiki/CompactFlash

(2) https://www.pcmag.com/news/25-years-of-compactflash-a-look-back-at-the-pioneering-format

(3) http://camera-wiki.org/wiki/CompactFlash

CompactFlash Type I

CompactFlash Type I cards were the original design for the CompactFlash standard. They have a thickness of 3.3 mm and were first introduced by SanDisk in 1994 (CF+ and CompactFlash Specification Revision 2.0, 2004).

Some key physical specifications of CompactFlash Type I cards include:

  • 3.3 mm thickness
  • 36.4 mm width
  • 42.8 mm length
  • 50-pin connector

In terms of performance, CompactFlash Type I cards have a maximum data transfer rate of up to 20 MB/s in the original standard, though later revisions increased this to over 100 MB/s (CompactFlash, 2022). The cards use parallel ATA interfaces and command sets.

CompactFlash Type I cards are commonly used in older digital cameras, camcorders, PDAs, media players, and other mobile devices. They were very popular in the late 1990s and early 2000s for providing removable data storage in consumer electronics. However, they have mostly been superseded by smaller form factors like SD cards in newer devices.

CompactFlash Type II

CompactFlash Type II cards were introduced in 1998 and have larger physical dimensions than Type I cards. According to the CF+ and CompactFlash Specification Revision 2.0 document from CF+ and CompactFlash Association, Type II cards are 5mm thick compared to 3.3mm for Type I (CF+ and CompactFlash Specification). The larger size allows Type II cards to incorporate advanced features not possible in the smaller Type I form factor.

Type II cards can offer higher storage capacities, with available sizes up to 128GB. They also typically have faster transfer speeds, with maximum theoretical transfer rates up to 167MB/s compared to 133MB/s for Type I. This improved performance makes Type II well-suited for use in high-end digital cameras that capture large image and video files.

In addition to digital cameras, Type II cards are commonly used in a variety of other devices that benefit from the fast speeds and large capacities, including DSLR cameras, camcorders, audio recorders, and industrial equipment. Type II slots can also accommodate tiny hard drives, which provide ruggedized storage well-suited for demanding environments.

Speed Classes

CompactFlash cards are assigned speed classes that indicate their maximum read and write speeds. Higher speed classes allow for faster transfer of data like photos and videos. There are two main speed class systems:

  • UDMA – Introduced in 2003, UDMA ratings range from UDMA 1 (16.7 MB/s) to UDMA 7 (167 MB/s). UDMA 7 cards are the fastest CompactFlash cards and are primarily Type II cards used in high-end DSLR cameras.1
  • x-rating – Introduced in 2010, x-ratings are displayed as a number followed by “x”, e.g. 133x. This indicates the maximum read speed in MB/s. A 1000x card has a max read speed of 150 MB/s.2

In general, CompactFlash Type I cards top out around 90 MB/s while Type II cards reach speeds over 150 MB/s. Professional photographers require the fastest speeds offered by Type II cards.


CompactFlash Type I cards are compatible with both Type I and Type II slots, whereas CompactFlash Type II cards can only be used in Type II slots (Transcend, n.d.). This is because Type I cards are thinner and can fit into both slots, while the thicker Type II cards can only fit into Type II slots. Electrically, the interfaces are the same for both types (Wikipedia, n.d.).

To use a Type II card in a Type I slot, an adapter can be used. Adapters allow the thicker Type II cards to be used in the thinner Type I slots by adjusting the size. There are simple passive adapters that just change the physical size, as well as more complex adapters that also convert the interface or support additional functionality (Nikon, n.d.). Using an adapter gives flexibility to use Type II cards with Type I slots and broaden compatibility across devices.

Cost Comparison

Type II cards generally cost more than Type I cards of the same capacity. This is because Type II cards are thicker and require more components, increasing the manufacturing cost.

For example, a 32GB Type I card may cost around $25 while a similar capacity Type II card costs closer to $40. Higher capacity cards show an even wider price gap between the two types. A 256GB Type II card could be $180-220 while a Type I may be $120-150 for the same capacity (1).

However, the price difference is justified by the superior performance and versatility offered by Type II cards. The extra cost brings faster read/write speeds and compatibility with more professional devices that demand high performance (2). If your camera or device can utilize UDMA modes, a Type II card is recommended to unlock the full speed potential.

Lifespan and Reliability

CompactFlash cards are known for their durability and reliability. The lifespan of a CompactFlash card depends on several factors including manufacturing quality and usage conditions. On average, most CompactFlash cards will last between 5-10 years with normal usage before performance starts to deteriorate.

CompactFlash Type I cards tend to have a slightly longer lifespan compared to the thinner Type II cards. The Type I interface and thicker physical design makes them more resistant to wear and tear over time. Industrial grade CompactFlash cards, which are designed for extreme conditions, can last over 10 years even with heavy usage.

Failure rates for CompactFlash cards are generally very low, around 2-3% according to industry data. The most common causes of failure are physical damage, manufacturing defects, and write/erase cycle exhaustion. Usage conditions like temperature, moisture, and shock can also impact failure rates. Overall, CompactFlash cards have proven to be a highly durable and reliable storage medium.

Studies have shown CompactFlash cards retaining data for over 10 years in good condition (source). Their exceptional lifespan and reliability make them suitable for long-term storage and industrial applications.

Popular Brands

When it comes to compact flash cards, the most popular brands are SanDisk, Lexar, and Transcend. SanDisk and Lexar are considered the top manufacturers for performance and reliability.

SanDisk offers a wide range of compact flash cards at different price points. Their Extreme line offers fast speeds up to 160MB/s read and 150MB/s write, making them ideal for high resolution photos and 4K video. The SanDisk Extreme cards utilize premium flash memory and controller technology for consistent performance.

Lexar also produces high-performing compact flash cards, such as their Professional 1066x line with speeds up to 155MB/s read and 140MB/s write. Lexar cards are known for their durability and reliability. Their cards utilize superior error-correction algorithms and flash controllers.

While SanDisk and Lexar are premium options, Transcend compact flash cards offer a more budget-friendly alternative. Their speeds top out around 90MB/s, so they may not be the best choice for high resolution media capture. However, Transcend cards provide decent performance at an affordable price point.

When choosing between brands, SanDisk and Lexar compact flash cards are recommended for their proven speed and reliability. Transcend offers a compromise of lower cost with acceptable real-world performance for many users.

Future Outlook

CompactFlash is declining in popularity compared to other formats like SD cards. According to a market analysis, CompactFlash sales are predicted to shrink through 2030 as SD cards become more dominant.

SD cards offer greater portability, higher maximum capacities, and better transfer speeds compared to CompactFlash. Most consumer electronics have moved to SD card slots rather than CompactFlash. Professional photographers are also transitioning to SD cards as their improved specs meet the needs for high-resolution photos and video.

While niche uses remain, CompactFlash faces stiff competition from the more compact and affordable SD card format. CompactFlash will likely persist in some industrial and specialized applications, but its era of mainstream popularity has come to an end.


In summary, CompactFlash Type I and Type II cards differ in their physical size, data transfer rates, and compatibility with devices. Type I cards are thicker and were the original CF cards introduced in the 1990s. They top out at speeds around 20-40 MB/s. Type II cards are thinner and were introduced later to support faster transfer rates. They can reach speeds of hundreds of MB/s with some faster variants like UDMA 7.

Type I cards are compatible with older digital cameras and devices with CF slots, while Type II offer better performance but may not work on legacy hardware. For modern DSLR cameras and devices demanding fast write speeds, Type II cards are recommended. However, for older electronics like digital audio recorders or industrial equipment, Type I may be the only compatible option.

In general, Type II CF cards are recommended for most use cases today given their faster speeds and better support. However Type I cards can still be useful for applications where absolute compatibility with older devices is needed, and maximum speed is not a priority.