The application of portable devices is growing sharply, therefore, the demands on accessible data storage also increase. SD card is not a single group, which has varied ranges available in size, class, interface, and specifications. The word “SD Card” represents a storage media including SD, SDHC and SDXC. Furthermore, it is just one type of bulk memory cards family, the size is the standard one. In order to create a right selection of SD card sizes, let’s start by understanding the use of SD card.

What does SD Card mean?

SD Card is a short term of secure digital card. It is one type of memory card developed by the SD Association. The main function of this media card is to store data such as documents, videos, photos, and the other contents. Also, it presently comes in three types indicating capacity ranges. There is SD, SDHC and SDXC. Standard SD cards go up to 2GB; SDHC represents the range of high capacity from 4GB to 32GB, and SDXC offers extended capacity from 64GB up to 2TB. Manufacturers also use sizes to define SD card capacity, in other words, we have SD card sizes from 128MB to 2TB.

Physical size of SD card

Bulk Memory cards have three major types following their physical size. SD cards are full size one, it is 32*24mm. Mini SD is another member and only half of it; Micro SD is the smallest one and is as small as a fingernail. To know all sizes and types of memory cards in details, let’s sort out as follow.

1.Secure Digital Cards (It includes three types)

• Size for Standard SD/SDHC/SDXC: 32mm*24mm (The physical size of these types is all same)
• Capacity: SD card is up to 2GB, SDHC supports from 4GB to 32GB, SDXC will be available from 64GB to 2TB

2.Micro SD Cards (same as SD offering three types)

• Size for Micro SD cards: 15mm*11mm (This dimension is same for all types)
• Capacity: Micro SD card – Up to 2GB, Micro SDHC – from 4GB to 32GB, Micro SDXC – from 64GB to 2TB

3. Mini SD Card

• Size: 21.5*20mm
• Capacity: Up to 2GB (As it is an old version, the available capacity is small)

Viewing the physical size can have an idea of the storage space. Obviously, SD card will need more rooms for installment. Thus, people use it often in DSLR cameras, tablets, 3D printers and the digital devices with enough spaces.

Labeling of SD Card

To distinguish SD cards in different capacities or specifications, manufacturers have use labels to tell information. As SD card delivers a standard dimension, it has a bigger space than Micro SD to present logo or the other description. Thus, you may find labels stick to the surface.

1.Capacity on the labels

• The density will be the number together with MB or GB, for instance, 8GB, 32GB and 128GB. These are indicating the capacity of SD cards

2.Speed on SD labels

• There are classes to tell speed. For example, you can find Class 4, class 6 and 10 there.  These are important data to tell the writing speed, which is 4MB/s, 6MB/s and 10MB/s by write.
• In addition, there are U1 and U3 also a guide for speed. In fact, U1 is identical to Class 10, but U1 means a minimum writing speed of 10MB/s; U3 requests the write not slower than 30 MB/s.
• Furthermore, the astonishing part is the speed of read. UHS-1 can reach up to 104MB/s by read, and UHS-II cards can hit 300MB/s. The structure of UHS-II card is a bit different, which has two rows of interface pins, this is the reason of high reading speed. Some SD labels will display the specific data of speed to expect good sales, so does SD card sizes.

3.Video speed

• UHS cards has a specific parameter for video shooting. There are V30, V60 and V90, which tells the minimum write speed at 30MB/s, 60MB/s and 90MB/s.

With the info of SD label, users can positively receive basic specification from it. Moreover, it can help people make right purchase.

Order appropriate SD card Capacity

Although users can understand basic info from labels, they are hard to make right purchase. Even there is no limit on budgets, the largest capacity may not fit the device. Prior to order SD cards, it is important to know capacity options in the market. What’s more, it is essential to check with the parameters of your equipment.

1. Old cameras: They only can support up to 32GB in SDHC
2. Latest smart phones: They can use up to 2TB

Therefore, getting the most appropriate SD card is the right way to make purchase.

Besides it, we need to research out the performance of SD card.

1. SD card in high capacity: it normally adopts TLC flash, which delivers fast speed but short lifespan.
2. SD card in low capacity: it uses SLC and MLC flash that helps extend life circle.

At present, the resolution of video and photo is reaching 4K and 8K, it requests one SD card in larger size and higher speed. Thus, 64GB is a basic choice; or you can go for 128GB and 1TB instead as if you have enough budgets.

All in all, selecting SD card sizes is following your actual needs and the requirement of devices. In case you have no idea of the status of equipment, you can collect 8gb, 32GB and 64GB SD cards to test. You will know the right SD card when the device can work after connection with this storage media.

Format size of SD card

Every SD card has file system, this is different from capacity by capacity.

• Format FAT: 4GB or smaller one
• Allocation unit size: 16KB
• FAT 32: from 8GB up to 64GB
• Allocation unit size: 32KB
• EXFAT: supports 64GB or above
• Allocation unit size: 128KB
• NTFS: from 64GB to 2TB

In fact, SD card performance is a bit affected by allocation unit. As you need to select default allocation unit size when formatting, the selection is linking to the density.

Small allocation unit sizes will take more time for data accessing, but large unit sizes can cause more waste. So proper use on unit sizes can bring efficiency on application. For instance, you can go for small size if you just load a few files. However, a large allocation size could be helpful for improving reading and writing if you need store video or films.

Final thought

The performance of SD card is directly affecting by various aspects such as size, speed, file system, video captures and flash type. To purchase a perfect card for photography or any institution, it is wise to know about these factors before any wholesale purchase.

The new mobile phones in 2022 supporting external storage were few, such as the Sony Xperia 1 IV and Huawei Mate Xs 2. These new models support to use bulk Micro SD card. I’m not sure when mobile phones started progressively losing the ability to support such expansion. Ordinary consumers can only purchase phones with higher capacity if they wish to increase their memory space. Is it true that we don’t require bulk Micro SD cards expansion? A questionnaire study on memory card expansion for mobile phones gets start recently.

Bulk Micro SD Cards

In the first, users were asked how important SD memory card expansion is to them, and we can see that 45% of the respondents said it was “very good but not very significant”. And nearly 40% said: “I will not buy a mobile phone without SD memory card expansion.” About 15% of the respondents selected “I don’t need it”

How important is SD memory card expansion to you?

In the second poll question, “How much storage is in use on your mobile phone right now?” , 128GB to 256GB accounts for up to 35.58% of the respondents, and 64GB to 128GB is the second-largest group. Those who have more than 256GB make up the third group, and the remainder is in smaller proportions.

What is your phone’s storage capacity like?

Manufacturers of mobile phones are gradually discontinuing SD memory card expansion. On the one hand, each additional hardware on phone will raise its price and weight due to the cost. On the other hand, supporting SD memory card expansion will restrict sales of versions in high capacity. Another reason is that the read and write speeds of SD memory cards are very slow. Even the fastest SD memory cards in the market only have one-tenth of those of today’s mobile phones. Comparing to some latest phones, the speed of storage cards is even slower than that. The user experience will suffer in such a circumstance. As a result, manufacturers of mobile phones have every right to control the weight issue. The solution is not to use SD memory card as expansion.

The following are some of the user comments:

Comment 1

The speed of the mobile phone is not the reason for missing SD card slot. It is entirely a matter of price! When a domestic mobile phone increases to 128G, the price gets extra 300 yuan. While buying a 160MB/S 128G SD card, it costs only a few dozen yuan. It is clear that including a SD card slot, the net profit will get 200 yuan less. It all depends on the pricing, mobile phone suppliers will not care if customers desire high capacity or not. Invest less money with a phone with less memory. People expect additional phone storage when take pictures and videos. Also, WeChat images and videos take up a lot of memory. The 128G smartphone is insufficient! Therefore, internet users should avoid from the tricks and not purchase a mobile phone with a large capacity.

Comment 2

Mobile phone memory is expanding. Furthermore, chip updates and replacements are taking longer, and users save more content in mobile phones than ever before. When you switch phones, it takes hours for transferring more than 100 GB of content to the new phone. Then you need to spend hours on uploading and downloading data. That is just a phone of around 100 GB. How will you manage a smartphone that has larger storage than 500 GB and 1 TB in the future? The data in mobile phone is not 100% safe, you may accidently lose it or suffer damage. Therefore, it is necessary to get a backup on memory. In fact, memory cards work quite fine. You can complete this process in a minute when you replace the memory card.

Comment 3

I enjoy listening to songs, and I need to download music tracks. I never make a phone purchase if there is no memory card, as the space is not enough.

Comment 4

The availability of a memory card is practical. The data may be disappearing if the mobile device gets breaks. Some people say that you can store your data in online disk. However, there is a download speed limit of the network if you are not a member.

Comment 5

Type-c connector is gradually replacing old USB port. Also, the detachable battery has altered to an integrated battery. You may barely find headphone jack in new phones, and only the charging port is available. In this way, it is convenient for selling blue tooth headphones. Additionally, the universal charger is no longer available, while the power banks are getting popular. It is a revolution of phones, why we still need keep micro-SD slot for storage?

Comment 6

Using an SD card has two main advantages. 1. Typically, the data will not get damage if you store it in card, it is a great protection in case the phone develops a problem. Moreover, you won’t be hesitant to reinstall the operating system after simply taking out the card. Second, you can simply change the card if you swift to another machine. Otherwise, how can you transfer anything 120G from the old phone to the new phone?

Comment 7

The bulk Micro SD card is in perfect working order. People love storing all important pictures and videos in the phone’s memory. While all unimportant music videos, TV shows and movies are stored on the SD card. If there isn’t an SD card, your phone is insufficient. And you’ll have to get a new one. This is how producers of mobile phones might generate revenue.

Comment 8

I like to take pictures, therefore I consider whether a bulk Micro SD card is available for a mobile phone. The storage of a mobile phone itself may not have enough room for the thousands of images, memory cards are the best solution. I was wondering if the SD card of the mobile phone can be exit and load with one key.

Given usb flash drive now serves as an indispensable tool for transferring files, this passage introduce details of usb flash drive as exquisite as possible, which cover the introduction of performance, testing software, usb flash drive solution type, usb flash drive master, flash memory, stability and simplified description.

The good news is that your camera user manual will tell you the memory card format and the minimum speed level you need to buy. You need to figure out the capacity and choose your price range. Finally, you must be sure to use one card reader compatible with your card. Otherwise, you may find that the transmission speed is much slower than you want.

Mobile phone USB Flash Drive is every convenient and can help you expand the capacity of your mobile phones. As our storage demands get high each days, it probably would be our best choice in the future.

MLC has more capacity and low price

SD cards are widely used in many devices, from camera tablets to mobile phones. There are various of SD cards in the market. The author here recommends you 10 of the SD cards with the best performance, feel free to choose the card you need.

The newly launched crystal U disk is very beautiful, it is half metal and half crystal. It combines aesthetics and practical use, a good choice for face judgers.

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A leading global chip provider, Realtek Semiconductor designs and produces a wide range of chip solutions for online media, communication networks, computer peripherals, and multimedia applications. Its chips are used in such products as the