Does SD card increase storage?

Yes, adding an SD card definitely increases the storage capacity of a device like a smartphone, camera, or tablet. SD cards provide removable, expandable storage that can supplement the built-in storage of your device.

How do SD cards work?

SD cards are flash-based removable memory cards that use non-volatile storage to save data. They connect to devices using SD card slots or microSD card slots. Once inserted, they act as additional storage space for your device. The SD card does not actually “expand” the existing built-in storage, it just adds more storage capacity in the form of the removable SD card.

Types of SD cards

There are several types of SD cards that offer different storage capacities:

  • SDSC (Standard Capacity) – Up to 2GB
  • SDHC (High Capacity) – Between 4GB and 32GB
  • SDXC (Extended Capacity) – Between 64GB and 2TB

Newer card types have higher maximum capacities, but are backwards compatible with older host devices, albeit limited to the maximum capacity the host device supports.

Speed classes

SD cards are also assigned speed classes that signify their minimum guaranteed transfer speeds:

Speed class Minimum speed
Class 2 2 MB/s
Class 4 4 MB/s
Class 6 6 MB/s
Class 10 10 MB/s
UHS Speed Class 1 10 MB/s
UHS Speed Class 3 30 MB/s

Higher speed classes allow for faster read/write speeds which is important for recording and transferring large media files quickly.

Benefits of using an SD card

Here are some of the major benefits to using an SD card for extra storage space:

Removable and portable

SD cards can be easily inserted and removed as needed. Their small size also makes them extremely portable so you can carry extra storage space in your pocket.

Inexpensive cost per gigabyte

SD cards provide an affordable way to add substantial chunks of storage. Cost per gigabyte is low, especially for higher capacity cards.

Supplement internal storage

Phones and tablets only come with a fixed internal storage capacity. Popping in an SD card can instantly increase that without having to buy a new device.

Transfer files between devices

SD cards make it easy to transfer photos, videos, and other files between different devices like cameras, phones, and computers.

Store and access different types of files

From media files to documents, SD cards can expand the type of files your device can store and access.

Back up important data

SD cards can serve as a backup storage location for your most important files.

What can you use an SD card for?

Here are some of the most common applications of SD cards:

Digital cameras

SD cards are the primary storage medium for digital cameras to store photos and videos. Different classes allow for various transfer speeds ideal for HD video recording.


Many Android phones have SD card slots to augment limited internal storage for apps, photos, and other media.


Tablets like the iPad do not always have expandable storage, but many Android tablets do support SD cards.

Handheld gaming

Gaming handhelds like Nintendo Switch use SD cards to download games and save progress.


Camera drones use SD cards to save aerial footage captured in flight.

Dash cams and security cameras

Dash cams and security cameras buffer footage onto SD cards for storage and playback.

PCs and laptops

Laptops and desktop PCs can use SD card slots to quickly transfer files or expand limited onboard storage.

Factors to consider when choosing an SD card

If you’re looking to buy an SD card, keep the following factors in mind:


Make sure the SD card type (SDSC, SDHC, SDXC) is supported by your device.


Choose the right capacity based on how much extra space you need. Higher capacity cards are better for future needs.

Speed rating

A higher speed class rating ensures better transfer speeds for recording video or burst photo capture.


Stick with major brands like SanDisk, Samsung, or Kingston for reliable performance.


Cards can range from $10 to $100+ depending on capacity. Find the sweet spot between price and capacity you need.


Opt for cards with longer warranties around 10 years for greater peace of mind.

Drawbacks to using SD cards

While very useful, SD cards do come with some disadvantages to consider as well:

Easy to lose and damage

Their small size makes them easy to misplace and the lack of enclosure can expose the cards to damage.

Limited storage lifetime

SD cards can wear out after a certain number of erase/write cycles, reducing their lifespan compared to internal storage.

Slower than built-in storage

SD card transfer speeds are generally not as fast as the internal storage of a device.

Not always supported

Some devices like iPhones and iPads do not support expandable SD card storage.

Spotty compatibility

Newer/larger capacity cards may not work in older host devices due to compatibility restrictions.

SD card storage size examples

Here are some examples of approximate file storage capacities for different SD card sizes:

SD card size Photos Songs Videos (at 4GB per hour) Documents
32GB 6,000 photos 8,000 songs 8 hours videos 425,000 pages
64GB 12,000 photos 16,000 songs 16 hours videos 850,000 pages
128GB 24,000 photos 32,000 songs 32 hours videos 1.7 million pages
256GB 48,000 photos 64,000 songs 64 hours videos 3.4 million pages
512GB 96,000 photos 128,000 songs 128 hours videos 6.8 million pages

As you can see, even a moderately sized SD card can increase your storage by gigabytes to allow storing thousands of files.

SD card speed test comparisons

The speed class rating of an SD card signifies its minimum guaranteed transfer speed. However, the real-world sustained speeds can vary based on the host device capabilities. Here are some sample speed test comparisons between different speed class SD cards when used with a digital camera:

SD Card Class Max Read Speed Max Write Speed
Class 2 10 MB/s 5 MB/s
Class 4 15 MB/s 8 MB/s
Class 10 40 MB/s 15 MB/s
UHS-I U3 95 MB/s 85 MB/s

As you move up in speed class, the real-world transfer speeds get significantly faster. A UHS-I U3 card can deliver smooth 4K video recording and quick burst mode shots.

SD card speed comparison during burst mode photo capture

SD Card Class Speed Buffer Size Time to Clear Buffer
Class 2 0.9 MB/s 7 photos 8 seconds
Class 4 1.7 MB/s 14 photos 8 seconds
Class 10 15 MB/s 100+ photos 5 seconds
UHS-I U3 60 MB/s 100+ photos 2 seconds

For burst photo capture, higher speed SD cards can sustain much faster write speeds to clear the camera’s image buffer quickly for uninterrupted shooting.

How to choose the right SD card size

Choosing the ideal SD card storage capacity depends on a few factors:

Device support

Check your device’s maximum supported card size. Many smartphones support up to 512GB SD cards.


Higher capacity cards cost more. Decide how much you can spend for the required capacity.

Intended use

Calculate the potential storage needed based on how you intend to use it. Photos and videos consume more than documents.

Future needs

If you plan to store increasing amounts of data over time, go with a higher capacity card now to accommodate future growth.

In general, it’s better to err on the side of more storage if your budget allows. A 128GB or 256GB card can cover most needs for the foreseeable future.

Tips for getting the most out of your SD card

Here are some tips to maximize your SD card’s performance and storage lifespan:

Buy from reputable brands

Stick with trusted brands like Sandisk, Samsung, Lexar, Kingston, etc. Avoid cheap knockoffs.

Check compatibility

Refer to your device manual and the SD Association’s specs to verify compatibility.

Match speed class to usage

Use speed class 10 or higher cards if recording HD video. Class 4 suffices for standard photos.

Enable caching

Caching frequently accessed data improves SD card read/write efficiency.

Use File Allocation Table (FAT)

FAT greatly improves SD card performance compared to exFAT for devices that support it.

Regularly back up data

Back up your SD card contents periodically in case the card gets corrupted or damaged.

Handle with care

Be careful when inserting/removing cards to avoid physical damage. Store in protective case.


Overall, SD cards are an inexpensive way to massively expand the storage capacity of your smartphone, camera, drone, gaming handheld, or other compatible device. Their portable, removable nature makes transferring data a breeze. Just be sure to choose the right card in terms of compatibility, capacity, and speed rating for your particular needs. With proper care and handling, an SD card can serve for years as a worthwhile supplementary storage upgrade.