It can be frustrating to insert a brand new SD card into your device, only to have it say there’s little or no free space available. This is actually a very common issue that many users face when setting up a new memory card. There are several key reasons why your shiny new SD card may falsely appear to be full right out of the packaging.
In this article, we’ll outline the main causes for this phenomenon and provide some troubleshooting tips to help you get your new SD card working properly. We’ll also offer recommendations on how to avoid fake capacity cards and ensure you purchase reliable SD cards that live up to their labeled storage capacity.
By the end, you’ll understand exactly why new SD cards show they’re full, along with actionable steps to resolve this vexing issue. Let’s dig in so you can start actually using that new SD card that seemed full at first glance!
Manufacturing Process
SD cards are manufactured using a process called semiconductor fabrication, which involves creating silicon wafers and etching integrated circuits onto them (1). This etching process pre-allocates some space on the SD card for internal functions, formatting information, and performance optimizations (2). As a result, some of the stated capacity is used right from the factory, before the SD card even reaches the consumer.
Specifically, SD card manufacturers reserve part of the total capacity for spare blocks, metadata, wear leveling algorithms, and file indexing (2). This reserved space allows the card to handle bad sectors, maintain performance as it ages, and keeps track of where files are located. The pre-allocation means that the full stated capacity is not available for users to store their own files and data.
In summary, the manufacturing process for SD cards results in some capacity being used upfront before the card is ever used. This pre-allocated space accounts for why a brand new SD card’s available capacity is slightly less than the advertised capacity (1).
File System Overhead
The file system on SD cards uses some space for metadata and overhead. When you format an SD card, it creates a file system structure to organize the data. This takes up space on the card that is not available for regular file storage.
For example, the FAT32 file system commonly used on SD cards has a file allocation table (FAT) that keeps track of where files are located on the disk. As you add more files, the FAT grows larger and takes up more space. There is also a root directory and other metadata. This can use several megabytes of space on the card (Source).
Other file systems like exFAT and NTFS have less overhead than FAT32, but still use some space. For example, NTFS uses metadata to support journaling and other advanced features. The exact amount depends on how the file system is implemented.
In general, you can expect anywhere from 1-10% of an SD card’s space to be used for file system overhead. This is normal, but explains why brand new cards show less available space than the advertised capacity.
Fake Capacity Cards
Some dishonest sellers will modify the firmware on SD cards to falsely report a larger storage capacity. For example, they may take a 16GB card and modify it to claim it has 256GB of space. According to iBoysoft, these fake capacity cards use various techniques to achieve this deception.
When you copy files to these cards, they will appear to work normally up until the actual capacity is reached. After that, new data will start overwriting old data in a loop. You may begin to see files disappear or become corrupted as a result.
To spot these fake SD cards, you can use tools like SD Card Formatter or H2testw to check the actual capacity. The test will reveal the true size, which is usually much smaller than claimed.
Reputable brands like SanDisk and Samsung are less likely to sell fake SD cards. Be wary of deeply discounted cards from unknown sellers online. Always test new cards before copying irreplaceable photos or data.
Pre-loaded Files
Note that some SD cards come with pre-loaded files taking up space like manuals. Some manufacturers will include user manuals or guides as PDF files pre-loaded onto the SD card [1]. Companies like Bulk Memory Cards also offer preloading services where they can add music, videos, documents or other files to SD cards before shipping them out [2]. While convenient, these pre-loaded files can quickly eat up storage space on the card.
Before concluding a brand new SD card is defective or smaller than advertised, check to see if it contains any hidden pre-loaded files. Reformatting the SD card should wipe these files and free up the full advertised storage capacity.
Camera File Overhead
Modern digital cameras, especially DSLRs and mirrorless models, produce very large image files in proprietary raw formats like CR2 or NEF. These uncompressed raw files contain every bit of data captured by the camera sensor and can be over 20-30 MB each (1). The tradeoff for all this extra image data is that raw files take up significantly more storage space compared to compressed JPEG files. For example, a 16 GB SD card that can hold thousands of JPEGs may only hold a few hundred raw images.
In addition to the raw file size, most digital cameras also generate sidecar files with metadata and thumbnails for each image. This can add an extra 50-100 KB of overhead per photo (2). Furthermore, due to write speed limitations, many cameras don’t immediately save the image file. Instead they first write it to a fast internal buffer before slowly transferring it to the SD card. This process ties up the card’s controller and creates additional file fragmentation and overhead that further reduces the number of images that can be stored (3).
So in summary, the massive file sizes of camera raw images coupled with related camera file overhead can dramatically decrease the usable capacity compared to the card’s stated size. Photographers shooting uncompressed raw should be aware of this limitation when purchasing SD cards.
(1) https://www.dpreview.com/forums/thread/3451841
(2) https://photo.stackexchange.com/questions/115116/whats-causing-my-camera-to-slow-down-after-the-image-was-saved
(3) https://groups.io/g/ccdciel/topic/how_to_reduce_image/70906659?p=
Troubleshooting Tips
If your new SD card is saying it’s full when you know it should be empty, there are a few things you can try to diagnose and fix the issue:
First, use your computer’s file explorer or a third party app to check the card’s properties and view the total vs free space. Sometimes the camera or device does not properly read the available capacity (source).
Next, look for any pre-loaded content on the card, like demo photos, videos or software. You may need to manually delete these files to free up the expected space (source).
It’s also possible you have a counterfeit or fake capacity card that claims to be a higher size than it really is. There are utilities that can test and verify the true capacity of your SD card.
Additionally, check your camera or device settings. Sometimes there are options to reserve space for system files that can incorrectly show the card as full.
As a last resort, you can safely format or reformat the SD card using your computer or camera to wipe it completely clean and reclaim all available capacity.
Following these tips should help diagnose if your new card is truly defective or being misreported as full prematurely.
Buying Recommendations
When buying an SD card, it’s important to purchase from reputable brands and retailers to ensure you get a legitimate card that matches the advertised capacity. According to TechRadar, some of the most trustworthy SD card brands include SanDisk, Samsung, Sony, Lexar, and Kingston. These brands undergo rigorous testing and have a proven track record for quality and accuracy in their stated capacities.
Avoid buying SD cards from unknown brands on marketplaces like eBay or Amazon, as there is a higher risk of getting counterfeit cards. Stick to well-known retailers like Best Buy, B&H, Adorama, or directly from the manufacturer. Comparing prices can help identify deals that seem too good to be true.
Once you receive the SD card, use an app that can scan for fakes, such as h2testw, to validate the card’s capacity. Run a full scan, which will fill the card with test data and verify if the stated capacity is correct. This can identify cards that have been manipulated to display false capacities.
Avoid buying used or secondhand SD cards, as their history and reliability is uncertain. When possible, purchase SD cards directly from the manufacturer or authorized retailer to minimize the risk of getting counterfeit or tampered cards.
Formatting the SD Card to Restore Full Capacity
One of the main solutions to restore the full capacity of an SD card is to properly reformat it. When an SD card is formatted, a file system is created that organizes how data is stored on the card. The most common file systems for SD cards are FAT32 and exFAT.
Sometimes SD cards can become corrupted, which can cause them to not show their full capacity. Reformatting the card resets the file system, erasing any corruption that may be limiting the available space. Some steps for formatting an SD card to restore full capacity:
- Using Windows, access the SD card properties and select “Format”. Choose exFAT or FAT32 file system.
- On Android, go to Settings > Storage, tap on your SD card, and choose “Format”. Pick FAT32 for cards 32GB or less, exFAT for larger cards.
- With Mac OS, launch Disk Utility, select your SD card, click “Erase”, and rename the volume if desired. Choose exFAT format.
Formatting deletes all data on the card, so be sure to back up your files first. After formatting, the card should now show its actual, full capacity.[1]
Conclusion
So why does your brand new SD card say it’s full right out of the package even though it’s a high capacity card? There are several potential reasons that we covered:
- Manufacturing processes use up a small percentage of the storage space
- The file system the card uses takes up space
- Fake capacity cards report false size
- Pre-loaded files were added by the manufacturer
- Camera file overhead from metadata etc can show capacity used
The main solutions are to reformat your card in the device, check if your camera has pre-loaded demo files, or upgrade to a new card from a reputable manufacturer. With high capacity cards these days, some used space is normal. But if your card capacity seems way off, it may be counterfeit. Stick to trusted brands and sellers to avoid fake cards.
Following proper formatting, your SD card’s true available space will be revealed. And you can start snapping photos or shooting video without worrying about your storage.