Why Freeing Up Storage Space Makes Your Android Phone Faster

Key Takeaways

  • Flash memory slows down as it fills, causing your phone’s performance to suffer.
  • Keep at least 10–15% of your phone’s storage space free for optimal speeds.
  • Easy ways to free up storage space include deleting duplicate files, compressing videos, and uninstalling unused apps.


Our smartphones have more storage than ever, but they also come equipped with powerful cameras that capture storage-intensive photos and videos. Combine that with modern app sizes, and your phone fills up in no time. But how does low storage equate to poor performance?


Your Phone Uses a Type of Flash Memory

Modern Android flagships use a type of very fast flash storage called Universal Flash Storage (UFS). UFS is a newer standard that uses 3D NAND technology to achieve fast and reliable data transfers. The latest standard of 3D NAND flash memory in smartphones is UFS 4.0, with a bandwidth of up to 23.2Gbps per lane. It’s much faster than eMMC, another type of flash storage you might encounter in very cheap smartphones, tablets, and TV boxes.

Whichever type you have, all follow the same general operational principles. Flash storage is made up of floating-gate cells that store electrons, which utilize the bit system to represent ones when present or zeros when absent. These stored ones and zeros represent your apps, images, videos, and other files. Cells are organized into pages that typically hold 16KB of data, and they’re the smallest units that can be read and written. Pages make up blocks, which typically hold 256 pages and are the smallest units that can be erased.

Flash Memory Slows Down as It Fills

Flash storage uses an oxide layer in the floating gate that electrons pass through. As the oxide wears down from read/write cycles, cells degrade in performance and storage capacity. Flash storage uses sophisticated algorithms like wear leveling that minimize degradation in sectors to make the impact negligible. When your storage is filled up, your smartphone has to use every sector available, including the slow and degraded ones.

All these different processes slow down your sequential read and write speeds. The reason your phone starts feeling sluggish is that apps need to store temporary files called data and cache. Without any space available, apps won’t work correctly, and you’ll probably encounter errors warning you that you’re out of space. I ran some tests using CPDT Benchmark at different storage capacities on my smartphone, and the results are consistent with the theory.

As you can see, even a few gigabytes of free space has a remarkable effect on sequential read speeds. The performance of sequential write speeds was a bit random, likely because my phone had to copy and delete blocks of data to reorganize them while simultaneously writing the new data. I took the screenshot with 10.2GB of free space after the one with 1.6GB of free space, so the sequential write speed results make sense. Once the storage was nearly filled, my phone started to struggle with basic tasks like opening apps and typing.

Keep 10–15% of Your Storage Free for Optimal Speeds

Keeping half of your phone storage empty is both impractical and unrealistic. Even basic apps like Facebook now take up over 1.2GB together with their temporary files. Based on the knowledge of how flash storage works and the performance metrics above, it is recommended to keep at least 10% of your storage empty at all times. To account for temporary and potential new files, such as photos, leave at least 15% empty space.

Tips on How to Free Up Storage Space

Running out of storage already? Fortunately, there are many ways to clean up space on your Android smartphone that won’t negatively affect your user experience. Here are my favorite methods to free up space:

I guarantee that you can free up over 10GB by doing only a couple of these things. If your storage was previously filled up, you’ll notice the difference immediately.


Your smartphone doesn’t need a significant amount of free space to perform at its best; you only need to keep a small chunk of your storage space free. Keeping your phone clutter-free will slightly improve performance, but an old phone will still struggle to keep up as your apps continually receive updates. If you find yourself running out of space constantly and find the performance subpar, maybe it’s time to upgrade to a new Android phone.

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