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How To Read X-Speed Ratings

Flash Memory Cards and X-Speed Ratings

With image files quickly growing in size, the time it takes to store or write those files to a Flash card has become increasingly important to buyers. Today, many Flash cards are sold with an “X” speed rating, giving users a performance indicator of how fast the card can transfer images.

First of all, it’s important to note that manufacturers define this rating differently and in some cases do not define it at all. Some definitions refer to the X-speed as “read” speed or “write” speed. Others use it to mean both and call it “data transfer” speed.

Will a higher rating improve performance?

Not necessarily. Your device itself is limited its own speeds, you should check these before making a purchase. As a general rule of thumb, digital cameras with up to 5 megapixels will work just fine with standard-speed Flash cards (less than 45X). Newer professional cameras designed for continuous shooting and/or with specifications of greater than 5 megapixels will benefit more from Elite Pro/Ultimate cards rated at 45X or above.

As the world's leading independent memory products manufacturer, Kingston uses only top-quality Flash chips and manufactures Flash products in state-of-the-art factories. All cards come with a lifetime warranty, free technical support and Kingston's legendary reliability, making Kingston the ideal memory choice for Flash storage devices.

Kingston's Elite Pro/Ultimate Flash Cards “X” Speed Ratings

Because digital camera and cell phone users generally care more about how long it takes to write data to a Flash card, Kingston uses the “write” speed for its X-speed rating. Also, read speeds are typically higher than write speeds for Flash cards so the write speed is a better indicator of performance. The following chart illustrates these ratings:

Kingston's Elite Pro/Ultimate Flash Cards
Elite Pro/Ultimate X-Speed Comparable MB/sec.
45X 6.75
50X 7.5
133X 20
266X 40
Source: Kingston Engineering Labs in benchmark testing.
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