The question of how long it takes to flash Android phone firmware arises for most users before starting the system update or recovery procedure. The answer to this is not a clear number, since the process depends on many variables: from the amount of data to the method of installing the software. On average, the entire procedure takes from 15 minutes to an hour and a half, but in rare cases it can take longer. Understanding these time frames is critical for planning actions so as not to interrupt the process halfway.
Many smartphone owners mistakenly believe that update time depends only on Internet speed, but this is only one of the components. The actual time of writing data to the internal memory of the device, checking the integrity of files and rebooting the system takes significantly more resources. If you plan to install custom firmware or roll back to an older version, the time commitment may differ from a standard OTA update. Let's look at each stage in detail.
Factors influencing the duration of the process
The first and most obvious factor is firmware size. A security update can weigh as little as 200 MB and install in 10 minutes, while a major Android update with a new skin can take 3-4 GB. The more data that needs to be unpacked and written to the system partition, the longer the device’s processor and storage work. For flagship models with fast chips, this time is reduced, but budget segments may suffer from delays.
The type of drive also plays a decisive role. Modern smartphones use UFS 3.1 or 4.0 memory, which provides high sequential write speeds. At the same time, older devices with eMMC 5.1 will copy the same amounts of data 3-4 times longer. This is a physical limitation of hardware that cannot be circumvented using software methods. Therefore, on the same firmware file Xiaomi Redmi Note the previous generation and the new one Samsung Galaxy S will show radically different results.
⚠️ Attention: If the installation process freezes at the "Application optimization" stage for more than 20 minutes, this may indicate damage to the system partition or lack of free space places.
Another important aspect is the number of installed applications. At the first start after the firmware, the Android system performs the so-called Dalvik/ART cache optimization. If you have more than 100 apps installed on your device, this step may take longer. The system checks the compatibility of each installed package with the new version of the OS, which requires significant computing power.
Before starting the firmware, free up at least 5-7 GB of free space. This will speed up the unpacking of archives and prevent errors in writing temporary files.
Comparison of installation methods: OTA, Recovery and PC
The choice of firmware method directly dictates the time costs. The easiest way is to update over the air (OTA). In this case, the phone itself downloads the package, checks it and installs it in the background or upon reboot. Here, most of the time is spent downloading the file via a mobile network or Wi-Fi. The installation process itself is usually automated and takes 10-20 minutes without user intervention.
Using Recovery mode (stock or custom, for example, TWRP) requires preliminary preparation. You need to manually download the firmware file, transfer it to the device and start the installation through the recovery menu. This method is often used to reset settings or install custom builds. The time here depends on the reading speed of the memory card or internal storage. Often this method is faster than OTA, since it eliminates the stage of background compatibility checking before installation.
The most labor-intensive method is the method of flashing firmware through a computer using special utilities like Odin, SP Flash Tool or Fastboot. Here the time is divided into preparing the PC, installing drivers and directly transferring data via a USB cable. Although USB 3.0 is fast, the partitioning and signature verification process may take longer than with a local installation. However, this method is the most reliable when restoring bricks.
Stages of firmware and their time costs
To understand where the time goes, you need to break the process down into its components. Typically, the procedure is divided into four key stages, each of which has its own duration. Understanding this sequence will help you not to panic if the screen freezes at a certain point.
The first stage is preparation and verification. The system reads the header of the firmware package, verifies the digital signature and verifies data integrity. On modern devices this takes from 30 seconds to 2 minutes. If firmware is used via a PC, this stage includes initializing the connection and sending commands to the bootloader.
The second stage is directly writing data to memory sections (System, Vendor, Boot, Recovery). This is the longest and most critical moment. The speed depends on the amount of information being recorded. At this time, the manufacturer's logo or robot animation is often displayed on the screen. A power interruption at this stage is fatal for the device.
The third stage is clearing the cache and formatting the Data partition (if a full reset is selected). This is necessary to prevent conflicts between the old settings and the new system. The process takes from 1 to 5 minutes, depending on how full the user’s memory is.
The final stage is the first loading and optimization. After rebooting, you will see a screen with the Android logo and the words “Optimize applications”. This is not a freeze, but normal system operation. Duration varies from 3 to 15 minutes. Only after this the desktop appears.
| Process stage | Average time (min) | Dependency |
|---|---|---|
| Signature and integrity verification | 1-2 | CPU power |
| Write system partitions | 5-15 | Memory speed and firmware size |
| Wipe Cache | 1-3 | Amount of accumulated temporary files |
| Optimizing applications (First Boot) | 5-20 | Number of installed applications |
The longest stage for the user is the first boot after the firmware, when the system optimizes the installed applications. Do not interrupt this process.
The influence of battery condition and temperature
The technical operating conditions of the device during firmware are often ignored, although they directly affect the time and success of the operation. The process of writing data to memory and the operation of the processor at high frequencies cause heating of the case. If the processor temperature reaches a critical value (usually around 80-85°C), the system will automatically reduce the clock frequency (throttling) to avoid overheating. This will lead to a significant slowdown in the firmware process.
The battery charge level is another critical parameter. Most official recovery will not allow you to start installation if the charge is below 30-40%. This is a defense mechanism. If you try to flash a phone with a dead battery through the engineering menu, the risk of power outage increases. A sudden loss of energy in the middle of bootloader recording will turn the smartphone into an unrecoverable “brick”.
⚠️ Attention: Firmware at ambient temperatures above +30°C or below +5°C can lead to unstable operation of the power controller and a recording error.
It is recommended to carry out the procedure at room temperature and a connected charger, even if the battery is fully charged. This will ensure stable voltage and eliminate power drops during peak moments of system load.
☑️ Ready for firmware
Specifics of custom firmware and root access
Installation of unofficial Android builds (Custom ROM), such as LineageOS, Pixel Experience or crDroid, often takes longer than installing stock software. This is due to the need to first unlock the bootloader. The unlocking process itself via the command fastboot oem unlock takes a couple of minutes, but requires confirmation on the device screen and often entails a complete data reset.
In addition, custom firmware often requires the installation of additional packages, such as Google Apps (GApps) or Magisk backbone modules to obtain root access. Each additional action in the Recovery menu adds its own minutes to the total time. You need to install ZIP archives one by one: first the firmware itself, then add-on packages, and only then wipe the cache. An error in the sequence can lead to an endless boot loop.
First boot time on custom firmware is usually higher, since the system needs to rebuild configurations for non-standard hardware or kernel. Users often report that the first boot of LineageOS on an older device can take up to 20 minutes. This is normal for optimizing the ART compiler for a new environment.
What is "Dirty Flash"?
This is a method for updating custom firmware without completely clearing the data section (Wipe Data). It saves time (no need to reconfigure the phone), but can lead to errors and instability if the firmware versions are very different. It is recommended to do "Clean Flash" when changing the major version of Android.
Typical problems and delays
Sometimes the firmware process takes an abnormally long time, exceeding all reasonable limits. Most often this is due to bad sectors on the device's flash memory. When the memory controller is unable to write data to a particular cell, it tries to do so again many times, causing huge delays. In the logs, this looks like a long pause before the error message.
Another common reason is incompatibility between the Recovery version and the firmware version. If you are trying to install Android 14 through an old Recovery designed for Android 11, the process may freeze at the partition mounting stage. The system will unsuccessfully try to decrypt data or verify signatures using algorithms that old software does not support.
It is also worth considering the human factor. An incorrectly selected firmware file (for example, for a different phone model or another region) may result in the installation process being interrupted immediately after it has begun, or the phone going into a reboot cycle. Always check the model code (for example SM-G991B) before starting the procedure.
⚠️ Attention: If the progress bar does not move for more than 30 minutes, the process is most likely frozen. In this case, a forced reboot is required, but there is a risk of system damage.
You can use the logging mode to diagnose problems. By connecting the phone to the PC and running the command adb logcat during the firmware (if you have access), you can see which driver or service the system stopped on. However, for the average user, this is a complex method, and it is easier to refer to the support forums for a specific model.
Use the original USB cable and USB 3.0 port (blue) on the PC motherboard, not on the front panel of the case, for maximum connection stability.
Frequently asked questions (FAQ)
Can I use phone during firmware?
No, this is absolutely impossible. During the installation of a new system, the phone reboots into a special mode (Recovery or Download), where the operating system is not active. The screen may be lit, showing a logo or setup log, but touch input and communications are disabled. An attempt to call such a phone will result in a “subscriber unavailable” signal.
How long does it take to unlock the bootloader?
The unlocking procedure itself via Fastboot takes about 1-2 minutes. However, on many modern smartphones (Xiaomi, Huawei) there is a mandatory waiting period of 7 to 168 hours after submitting an application to the official service. Only after this period has expired, the unlock command will work.
Why does the phone get hot and slow after updating the firmware?
In the first 24-48 hours after installing the new firmware, the system performs background indexing of files, uploading contacts to the cloud and optimizing databases. This creates a load on the processor. Usually after a couple of days the work stabilizes. If not, the firmware may not be optimized for your device.
Do you need to do a full reset (Wipe Data) when updating the Android version?
When updating within the same version (from Android 13 to Android 13.1), a full reset is not necessary. But when switching between major versions (from Android 13 to Android 14), it is strongly recommended to do a full reset to avoid system library conflicts and application errors.
What to do if the firmware is interrupted by 90%?
Don’t panic. Try holding down the power button and volume button (the combination depends on the model) to force a reboot. If the phone turns on, try flashing it again. If the phone shows no signs of life (black screen, no response to buttons), you will need firmware in Emergency Download (EDL) mode or a service center.