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: December 4, 2023

Filed Under: Memory Cards

I MAY get commissions for purchases made through links in this post.

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.

Fastest SD Card Speed Tests. With cameras getting improved 4K, 5K, and even 8K video recording and burst shooting features all the time, some of them need the write speeds that only the fastest SD cards provide. So here’s a roundup of the fastest SD cards based on my independent tests.
Fastest MicroSD Card Speed Tests. Need a fast microSD card? If you’re shooting 4K, 5K, or 8K video, high-speed burst-mode photos, or some other demanding use, speed matters. These are the results from my independent speed tests of the fastest microSD cards.
Types of SD Cards Explained. There are several different types of SD cards, as well as multiple speed rating systems and cryptic codes. Here’s a rundown of what the differences are.
UHS-I vs UHS-II on microSD & SD Cards. Wondering what the difference is between UHS-I and UHS-II with SD and microSD cards? Here’s an explanation.
A1 vs A2 SD cards and microSD Cards You might have seen new A1 and A2 speed ratings on some of the newer SD and microSD cards. So what do they mean? And when should you take notice of it?
SD Card Formatter App for Formatting, Wiping & Repairing SD & microSD Cards. Here’s a guide to using the SD Association’s official SD Card Formatter for preparing your SD and microSD cards for use.
How to Format SD Cards on Mac. Here’s a step-by-step guide for formatting both SD and microSD cards.
Best Free Data Recovery Software for SD Cards. Here’s a rundown of the best free data recovery software to use if you’ve accidentally deleted photos or videos from your SD card.
How to Rover Deleted Photos from SD Card: SD Card Recovery Options. All those photos you took have disappeared from the SD card. The good news is that there’s still a good chance you can recover photos from the SD card. Here’s what to do. Includes free and paid SD card recovery options.

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.