Flash Drive vs SD Card: Which One is Faster and More Reliable?

Flash drives outperform SD cards both in speed and reliability. Whereas SD cards max out at around 985 MB/s, flash drives can reach up to 40 GB/s of data transfer speed! However, thanks to their tiny form factor, SD cards can also be more useful in certain use-cases.

Hi, I’m Devansh. Having worked with SD cards and flash drives back since Symbian-run Nokia was the closest thing you could get to a smartphone, I know my way around these storage devices.

In this article, I’ll compare SD cards and flash drives in terms of data transfer speed and reliability, then I’ll answer some useful and interesting questions you might be curious about.

If you’re looking to get a new storage device but are torn between flash drives and SD cards to get the best speed and reliability, keep reading!

Flash Drive vs SD Card: Data Transfer Speed Compared

These days, data transfer speed has become very important. We all are dealing with large files and need to manage multiple devices at once. The quicker, the better. So, let’s compare SD cards with flash drives in the context of data transfer speed.

SD Card

Similar to flash drives, SD cards come in many shapes and sizes. Just like The Godfather, there are five families of SD cards, each with their own storage capacity limits. One of them is SDIO (Input/Output), which isn’t related to data, but here are the other ones.

First comes SD Standard Capacity cards, which can usually hold around 2GB of data; then we have SD High Capacity ones which go a notch higher up to 32GB; beating that out of the park are SD eXtended Capacity cards, holding up to 2TB; then the SD Ultra Capacity ones go up to a mind-boggling 128TB! Here are their respective data speeds.

InterfaceSD CardData Transfer Speed
DefaultSD, SDHC, SDXC, SDUC12.5 MB/s
SD ExpressSD, SDHC, SDXC, SDUC985 MB/s

As you can see, even in some of the best cards with advanced interfaces, the data speed is rather mediocre. Now, let’s talk about flash drives.

Flash Drive

Flash drives are typically much faster than SD cards. Whereas even high-end UHS-II cards max out at 312MB/s, standard USB 2.0 drives just start out at 480MB/s! Now, let’s look at the data chart. Compared to SD cards, I’m sure you’ll be impressed by what you see here.

InterfaceData Transfer Speed
USB 2.0480 MB/s
USB 3.05 GB/s
USB 3.110 GB/s
USB 3.220 GB/s
USB 440 GB/s

OK, so it’s clear as daylight by now that flash drives take the cake when it comes to data transfer speed. But, what about reliability? Even if your data is being shared at breakneck speeds across devices, it won’t do you any good if it’s not secure or if it gets corrupted often.

Flash Drive vs SD Card: Reliability Compared

Since both flash drives and SD cards use the same underlying NAND memory technology and have no moving parts, they aren’t much different when it comes to reliability. Both perform more or less the same.

Although it works for a long time, flash memory doesn’t last forever. In general, it can last around 10,000 to 100,000 write/erase cycles (source). Once you reach that ceiling, a portion of the total memory may get corrupted or lost. Other than that, it’s a reliable form of storage.

Now that we’ve discussed flash memory in general, let’s go over some points about SD cards and flash drives specifically.

SD card

There is no known definite lifespan of an SD card, although the theoretical limit is around 30 years. A good rule of thumb is that the higher the usage, the more prone it is to wear out, both in terms of internal memory cells and the build quality of the component.

The good news is, nowadays you can buy special “wear-leveling” SD cards which are able to distribute overall access to the memory across the card rather than a single location. These last longer without data loss and corruption than a standard SD card.

Then again, you also need to be aware of software bugs that disturb or pause data writing operations, power losses or glitches, and electrostatic discharges or overvoltage events. Any of these can disrupt operations and lower the reliability of the SD card.

At the end of the day, if you want the best chances of long-term data reliability for your SD card, consider purchasing the card from an SD Association-approved brand like SanDisk, Lexar, or Transcend.

Flash Drive

Although many of the above points are common with flash drives too since these also use NAND memory technology, they do still hold the high ground in this regard, and that’s thanks to their build quality.

Unlike SD cards, they come with a plastic case which gives them better protection from falls, scratches, and natural elements. In addition to that, they’re also not as easy to lose as SD cards. So, overall, they’re much tougher and durable which increases their everyday reliability.


I’ve now compared both SD cards and flash drives when it comes to speed and reliability. However, the debate doesn’t end there. There’s still a lot more to go over. Here are four interesting questions you might be curious about.

Which Lasts Longer: SD card or Flash Drive?

Since neither of them has any moving parts, they both will last long. However, with a plastic case, a proper controller chip, and a built-in capacitor, USB flash drives are built with durability in mind. So, more often than not, a USB flash drive will last longer than an SD card over extended everyday use.

Are SD Cards More Secure Compared to USB?

Both storage types use the same underlying memory technology. So neither is superior to the other when it comes to data security. Both also provide the option of encrypting your data to protect the stored contents.

Can I Use an SD Card as a Flash Drive?

Yes, all you need is a SD card to USB adapter. There are many great options out there, some can even hold several cards at once. Of course, make sure to get an adapter that is compatible with the card you’re using.

How Do I Transfer Files from SD Card to Flash Drive?

Just make sure to connect both the SD card as well as the USB drive to your desktop or laptop computer. Once connected, you can move files between them as you want. If you can’t connect them both simultaneously, you can use the local storage on the PC as a temporary intermediate too.

Final Thoughts

Now you know that flash drives perform much better than SD cards when it comes to speed and reliability. However, that doesn’t make SD cards entirely useless. They can still be used for devices that are too small for a flash drive.

To summarize – SD cards provide the best way to store files in small form-factor standalone devices like cameras and smartphones. Flash drives are a perfect way to access big files on the go with better speed.

What are some of your own experiences using SD cards and flash drives to store your files and applications? And which one do you think is better? Share your answer with me in the comments!

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  • failed

    this whole article is flawed and biased, its all going to depend on the components, brand and quality. its not a 1:1 comparison.
    in principle a good microsd card with a quality usb reader will outperform any standard usb stick and have a larger usage scene.

  • TwinsAtha

    GEMBIRD SD to USB CARD READER write stuff with 17mb/s, while my usb sticks write at 3.5 mb/s

  • A

    USB 2 transfer speed is 480Mbps, NOT 480MB/s
    USB 3 and above are Gb, NOT GB!

    • mike

      very important factor of (about) 10x there. THANKS

  • Vince

    My friend, using his PC, transferred his Hi-8 tapes from camera to SD card (Lexar 128G) thru a Clear-Click unit. He then lent the Clear-Click and the SD card to me so I could do the same. He had formatted the card on his PC. I transferred the first of my Hi-8 tapes thru the Clear-Click to his card and plugged the card (via adapter) into my Macbook Air, then storing the file on an external drive. I then formatted the card on the Mac AND the Clear-Click. After converting the next Hi-8 tape and inserting the card in the Macbook Air, it would not read the card. I tried it in two other Macs with same result. Is it your belief that PC/Mac compatibility is the issue…or could it simply be a corrupted card, even though the content was successfully stored on it thru the Clear -Click?

  • Kelly Bishop

    I prefer to store almost all of my files of my laptop on a Sandisk Ultra Fit flash drive. Since the Ultra Fit is so small and low profile, it’s as if it was part of the contour of the laptop, it doesn’t get snagged and it isn’t the USB Flash drives that are 1″ or so long than can get broken off. Using the 512 GB Ultra Fit is like having the hard drive on the laptop, but the Ultra Fit has the advantage of portability.

    I use the process of backing up my entire PC, so having the external Ultra Fit facilitates the functionality of allowing me to backup the entire laptop hard drive and restoring the entire PC anytime, without my having to be concerned about writing over the files that are on the Ultra Fit flash drive.

    That being said, the point that I’m getting to is that 512 GB can be not enough storage space, so until Sandisk or some manufacture comes up with a 1 TB or larger Ultra small Ultra Fit flash drive, the idea of using an SD card is a viable way to have external add on storage that doesn’t stick out and get broken off or catch on something.

    Reading your information, here Devansh, has helped me to decide to use an SD card along with the Ultra Fit to store excess files on. The types of files that I store on the SD card could be the files that are rarely used and files that don’t require fast speeds. I wish that SD cards were faster; that way I could store all of my files on a 1 or 2 TB SD card; and free up a USB slot.

    Or… is the Sandisk Ultra Extreme SD card fast enough at 200 MBPS fast enough to handle all speed requirements? Thank you.

    • Devansh

      Hi Kelly, thanks for reading my article! Regarding your query, I recommend you keep your current Sandisk Ultra Fit flash drive and get a mid-range extra SD card to back up excess files that don’t require fast transfer speed. This would be a more budget-friendly storage option than a high-end new 1TB Sandisk Ultra Extreme SD card. I hope this helped!