ThumbData on Android: why are these files needed and how to delete them without risk

Have you ever noticed that on your Is your Android smartphone suddenly running out of free space, even though you haven’t installed new applications or downloaded large files for a long time? Upon closer inspection, you can find strange files in the file manager with the name ThumbData —sometimes they take up hundreds of megabytes, or even several gigabytes. What are these files, why do they appear and can they be deleted without harm to the system?

Files ThumbData (or thumbdata3--xxxxxxxx.db, thumbdata4--xxxxxxxx.db) are hidden databases that Android creates to store thumbnails (previews) of images, videos and other media files. They are needed so that the gallery, file managers and other applications quickly show thumbnails of content instead of downloading full-size files each time. The problem is that over time these files grow to gigantic sizes, especially if you actively use the camera, save memes or download pictures from instant messengers.

In this article we will look in detail at:

• 🔍 What are ThumbData and how they work in Android
• ⚠️ Why do these files take up so much space and is it possible to reduce them
• 🗑️ How to safely delete ThumbData without losing media files
• 🛠️ Ways to prevent the thumbnail cache from growing again
• 📱 The impact of ThumbData on smartphone performance

What is ThumbData and why you need them in Android

Files ThumbData is part of the thumbnail caching mechanism, which has been used in Android since the earliest versions. When you open a gallery or file manager, the system does not immediately load full-size images (this would take a lot of time and resources). Instead, it shows reduced copies - preview, stored in special databases.

These databases have the format .db (SQLite) and are usually located in folders:

• 📁 /sdcard/DCIM/.thumbnails/ - for photos and videos with cameras
• 📁 /sdcard/Pictures/.thumbnails/ — for images from downloads and screenshots
• 📁 /sdcard/Download/.thumbnails/ — for media from the Internet

Each file ThumbData contains thumbnails for a specific type of content. For example, thumbdata3 is usually responsible for images, and thumbdata4 for video. The file name after the hyphen (thumbdata3--1967290298.db) is a hash that helps the system identify which media set the cache belongs to.

🔹 Why is this important? Without these files, the gallery and other applications would have to regenerate the preview each time, which would slow down the work and waste battery power. However, over time, the cache grows to an unreasonable size - especially if you: Why is this important? data-i="68">or

• 📸 Take a lot of high-resolution photos (for example, on Samsung Galaxy S23 Ultra or Google Pixel 7 Pro)
• 🎵 Save memes and gifs from Telegram, WhatsApp or VK
• 📥 Download video from TikTok or YouTube (even in low quality)
• 🔄 Frequently move files between folders (a new preview is created each time)

Why ThumbData takes up gigabytes of memory and how to check it

The main problem with files ThumbData is their tendency to grow uncontrollably. Unlike the regular app cache, which Android can clear automatically, these databases often remain untouched for years. Here are a few reasons why they grow:

1. Incorrect cleaning. Many file managers and cleaning utilities ignore hidden folders .thumbnailssince they are marked as system folders.
2. Duplicating thumbnails. If you edit photos (for example, in Snapseed or Lightroom Mobile, the system can create several versions of the preview for one file.
3. Application errors. Some galleries (for example, Mi Gallery on Xiaomi or Samsung Gallery) do not optimize the cache, leaving old thumbnails even after deleting the original files.
4. Database fragmentation. With frequent addition/removal of media files ThumbData "swell", but do not shrink back.

🔍 How to check the size of ThumbData on your smartphone?

1. Open any file manager (for example Files by Google, Solid Explorer or built in MIUI/One UI).
2. Turn on display of hidden files (usually in menu settings).
3. Go to folders DCIM, Pictures or Download and find the hidden folder inside .thumbnails.
4. Look at the file sizes thumbdata3--.db and thumbdata4--.db.

Device	Typical ThumbData size (with active use)	Maximum recorded size
Samsung Galaxy S22	300–800 MB	2.1 GB (after 1 year usage)
Xiaomi Redmi Note 11	500 MB–1.2 GB	3.4 GB (with frequent saving from Telegram)
Google Pixel 6	200–600 MB	1.8 GB (with enabled Google Photos)
Realme 9 Pro	400 MB–1 GB	2.7 GB (when using a custom gallery)

⚠️ Attention: If you see files ThumbData larger than 1 GB, this is a clear signal to clean up. However, do not rush. delete them manually - first read the safe methods below.

Is it possible to delete ThumbData without consequences for the smartphone

Yes, files. ThumbData can be deleted without risk to media files or system operation. They do not contain original images or videos - only their small copies After deletion:

• 🖼️ The gallery and file managers will temporarily load slower (until new previews are generated).
• 🔄 There may be a delay when opening a media folder for the first time.
• 📱 General the amount of free memory will increase.

🚫 What will NOT happen after deletion:

• ❌ Disappearance of original photos/videos.
• ❌ Malfunctions of the camera or gallery.
• ❌ Loss of account data or applications.

However, there are nuances:

⚠️ Attention: On some firmware (for example, ColorOS from Oppo/Realme or EMUI from Huawei) after removal ThumbData the gallery may temporarily display empty previews or placeholder icons. This is normal - the thumbnails will be restored after 5-10 minutes.

It is also worth considering that some system applications (for example, Google Photos) can automatically restore part of the cache from the cloud. If you want to completely reset the thumbnails, you will have to clear the cache of these applications as well.

How to safely delete ThumbData: 4 proven methods

There are several ways to clear the thumbnail cache. Choose the one that suits your skill level:

Method 1: Manual deletion through a file manager

The simplest method, but requires care.

Open a file manager with support for hidden files|Go to the DCIM/Pictures/Download folders|Find the hidden folder .thumbnails|Select all thumbdata*.db files|Delete them and empty the recycle bin-->

🔹 Advantages: does not require root access, works on any Android.

🔹 Disadvantages: you will have to repeat the process in each media folder.

Method 2: Clearing through the settings of the "Gallery" application

Many manufacturers add a cache reset option to their galleries:

1. Open Settings → Applications.
2. Find the gallery application (for example, Samsung Gallery, Mi Gallery, Google Photos).
3. Select Storage → Clear cache.
4. Restart your smartphone.

⚠️ Attention: On some devices (for example, Huawei or Honor), this option may reset not only the thumbnail cache, but also other temporary gallery data (for example, albums or tags).

Method 3: Use cleaning utilities (SD Maid, Files by Google)

Applications like SD Maid or Files by Google can find and delete unnecessary cache files, including ThumbData:

• 📱 In Files by Google: go in Clean → Application Cache → Gallery.
• 🧹 In SD Maid: select CorpseFinder → System → Thumbnails.

🔹 Plus: automatically finds all cache files, including hidden ones.

🔹 Minus: some utilities require root access for deep cleaning.

Method 4: Reset cache via ADB (for advanced users)

If you are familiar with Android Debug Bridge, you can clear the thumbnail cache with the command:

adb shell pm clear com.android.gallery3d

🔹 For custom firmware (for example, LineageOS) another command may be required:

adb shell rm -rf /sdcard/DCIM/.thumbnails/*
adb shell rm -rf /sdcard/Pictures/.thumbnails/*

⚠️ Attention: Incorrect use ADB can lead to system malfunctions. If you are not sure, use other methods.

How to prevent ThumbData from growing again

Deleting ThumbData is a one-time solution. To prevent your thumbnail cache from growing again, follow these tips:

• 📁 Clear the gallery regularly. Delete unnecessary photos and videos (especially duplicates and screenshots). The fewer media files, the smaller the cache.
• 🔄 Disable automatic backup to the cloud. In Google Photos go to Settings → Backup and synchronization and disable the option if you do not use it.
• 🛠️ Use lightweight alternatives to the standard gallery. Applications like Simple Gallery or QuickPic manage more efficiently cache.
• 📱 Limit caching for individual applications. For example, in Telegram You can disable automatic saving of media to Settings → Data and memory → Autoload media.

🔹 For users of custom firmware: Some assemblies (for example, Pixel Experience or Havoc-OS) allow you to disable the generation of thumbnails altogether. To do this, you need to edit the file build.propby adding the line:

ro.media.enc.thumbnail.quality=0

However, this may lead to previews not being displayed in the gallery at all.

📌 Useful life hack: If you often take screenshots, configure their automatic removal after 30 days using applications like Screenshoter or Screen Master. This will reduce the amount of unnecessary thumbnails.

What will happen if you completely disable ThumbData?

Without a thumbnail cache, the gallery will load full-size images every time you scroll, which will lead to:

✅ Increased loading time for albums (especially noticeable on weak smartphones).

✅ Increased battery consumption when viewing photos.

✅ Possible interface slowdowns.

Therefore, completely abandoning ThumbData is not recommended - it is better to control their size.

The influence of ThumbData on Android performance

Swollen files ThumbData affect the smartphone not only by the space it takes up. Here's how they can slow down the device:

• 🐢 Gallery brakes. When opening a folder with thousands of photos, the system tries to load all the thumbnails at once, which leads to freezes.
• 🔋 Increased battery consumption. Constant regeneration of previews (if the cache is damaged) drains the battery by 5–15% faster.
• 📉 Slowdown of the file manager. Applications like ES Explorer or FX File Explorer take longer to scan folders due to the large cache size.
• 🗃️ Memory fragmentation. Large files .db fragment storage, which worsens read/write speed.

📊 Performance test: On Samsung Galaxy A52 with 128 GB of memory and a bloated cache ThumbData (2.3 GB), the gallery opening time increased from 1.2 to 4.5 seconds. After clearing the cache, the delay was reduced to 1.5 seconds.

🔹 How to check the impact on your smartphone?

1. Launch the gallery and time the opening time of a folder with 500+ photos.
2. Clear ThumbData (by any method from the section above).
3. Repeat the test. If the difference is more than 2 seconds, the thumbnail cache is definitely slowing down your device.

⚠️ Attention: On devices with eMMC memory (as opposed to UFS), the impact of a fragmented cache is stronger. If your smartphone is older than 2019, cleaning ThumbData may give a more noticeable performance boost.

Common errors when working with ThumbData and how to fix them avoid

Many users make mistakes when trying to clear the thumbnail cache. Here are the most common of them and how to prevent them:

• 🚫 Deleting original media files instead of cache.
  How to avoid: Always check the file extension. ThumbData have format .db, and originals - .jpg, .png, .mp4.
• 🔄 Clearing the cache in only one folder.
  How avoid: Check DCIM, Pictures, Download and Movies —the cache can be in each.
• 🛠️ Using unverified "cleaners".
  How to avoid: Do not install applications like Clean Master or CCleaner —they often delete useful data. Use SD Maid or built-in Android tools.
• 📱 Deleting ThumbData on a root device without a backup.
  How to avoid: Before mass cleaning, make a backup of the folder .thumbnails on your PC.

🔹 Myths about ThumbData:

• ❌ "Removing ThumbData spoils the camera." - No, the camera generates new previews the next time you launch it.
• ❌ "These files are needed for Android to work." - No, they are only needed for the convenience of viewing media.
• ❌ "ThumbData contain personal data." - No, these are only thumbnails, without EXIF marks or other information.

📌 Tip for users Xiaomi: On devices with MIUI after cleaning ThumbData a notification “The gallery is optimizing media files” may appear - the system is restoring the preview. 5–10 minutes.

FAQ: Answers to frequently asked questions about ThumbData

❓ Is it possible to disable the creation of ThumbData forever?

You cannot completely disable the generation of thumbnails without root access, but you can reduce their size:

1. Use gallery with cache settings (eg Simple Gallery Pro allows you to limit the size of the preview).
2. Regularly clear the cache manually or via SD Maid.

On devices with root you can edit system settings, but this is risky.

❓ Why do they appear again after deleting ThumbData?

This is normal - Android restores the thumbnail cache when you first open a gallery or media folder. To slow down their growth:

• Delete unnecessary photos and videos.
• Disable automatic backup to the cloud.
• Use lightweight galleries.

❓ Do large ThumbData harm a smartphone?

The files themselves ThumbData do not harm the device, but:

• They take up valuable space on drive.
• Can fragment memory, slowing down reading/writing.
• If the cache is damaged, the gallery begins to slow down.

It is recommended to clear them every 2-3 months.

❓ Is it possible to transfer ThumbData to an SD card?

Technically yes, but it's pointless because:

• SD cards (especially class 10) are slower than built-in memory, which will slow down loading previews.
• Android is not optimized to work with external caches media.
• When you remove the card, the thumbnails will disappear.

It is better to clear the cache regularly than to transfer it.

❓ Why are there no ThumbData files on some smartphones?

This is possible for several reasons:

• The manufacturer uses a different caching mechanism (for example, Huawei in new versions EMUI stores thumbnails in /data/media/0/.estrongs).
• You use an alternative gallery that stores the cache in its directory.
• Files are hidden not only attribute .number, but also system rights (visible only with root).

Try to search for files by mask thumb* through the file manager.