Convert Memory Card X Speed Rating to MB/s

Here’s a simple converter to convert memory card X speed ratings to the more conventional (and useful) MB/s number.

X to Megabytes Per Second Calculator Header
Text & Photos By David Coleman
Last Revised & Updated:
Filed Under: Memory Cards

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Convert From X to Megabytes per Second

Simply choose the X speed rating from the drop-down list. I’ve compiled the list from common memory card X ratings.


Why This is Useful

It can be confusing knowing which memory card to buy for a particular camera. Some cameras need cards that meet minimum speed standards in order to function properly and have all of their features available. But the world of memory cards is littered with acronyms and jargon that doesn’t always seem to make sense.

Many memory cards carry speed ratings. The most common is a read speed rating. It’s often the highest number and sounds more impressive, but it’s also about getting data off the card. For cameras, it’s usually more important to know how fast the memory card can save data onto the card. And finding that number is often harder than it should be.

It can be even more difficult because memory card manufacturers are not always consistent in how they do it. Most stick to the conventional MB/s (megabytes per second / MBps) format. That’s pretty straightforward.

But some memory card manufacturers still write their cards’ speeds expressed in “X” or times. Times what? That’s where things start to get a bit silly. It’s actually an old way of measuring the speed of CD-ROM drives when the standard speed of a CD-ROM drive was 150KB/s. Each x, therefore, equals 150KB/s. But when was the last time you used an old-school CD-ROM? And how many of us have an intuitive sense of how fast that is? And how useful, really, is a number like 1067x when most cards are rated in MB/s?

So to make it easier to compare apples to apples when trying to work out the speed of a microSD or SD card, I’ve whipped up this super simple converter. It converts between memory card “X” ratings and the more conventional (and more useful) number in MB/s.

Memory Card Tools

Here are a few other related tools I’ve put together that can be useful when working with memory cards and data rates.

Converting Mbps to MB/s & X Speed Rating to MB/s

Another related and common calculation that often needs to be done when working with memory cards is converting the convention for measuring video bitrate (Mbps, Mb/s, or megabits per second) to the convention for measuring the speed of memory cards (MBps, MB/s, or megabytes per second).

So I’ve put together a simple calculator for that separately. You can find it here:

Memory Card Size Calculators

If you’re trying to figure out what size memory card to buy, it can be useful to know how much video footage from the camera you can fit on a card. Here are a few tools that can be useful for that:

Working with Memory Cards

Here are some related posts for making sense of memory cards and working with them.

Profile photo of David Coleman | Have Camera Will Travel | Washington DC-based Professional Photographer

Text & Photos by David Coleman

I'm a professional photographer based in Washington DC. Seven continents, up mountains, underwater, and a bunch of places in between. I've been shooting for 30+ years, and my my photos and time-lapse videos have appeared in a bunch of different publications from major newspapers to magazines and books, billboards, TV shows, professional sports stadiums, museums, and even massive architectural scrims covering world-famous buildings while they're being renovated. You can see some of my travel photography here and here.

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