On Monday, experts speaking to The Wall Street Journal about the ongoing smartphone encryption debate estimated that roughly "10 percent of the world's 1.4 billion Android phones were encrypted," compared to 95 percent of all iPhones. For iPhones, that estimate is based on data provided by the company's OS distribution chart—this isn't a perfect source since it also includes iPods and iPads. In any case, the vast majority of iDevices are running iOS 8 or 9 and thus all data on them is encrypted in a way that makes it impossible for Apple or others to directly access data on them without their passcodes.

The figure for Android phones is likely an estimate based on other sources, since it's impossible to get similar data from the Android distribution chart. Google has historically had trouble getting its hardware partners to encrypt their phones and even had to backtrack on promises that Android 5.0 phones would be encrypted by default because of performance concerns. Ultimately, the company was able to make encrypted storage a requirement for Android 6.0 phones that meet the required specs (Nexus devices have been encrypted by default since the Nexus 6 and 9 came out in 2014), but currently only 2.3 percent of all Android phones run Marshmallow. Even worse, only new phones that ship with Android 6.0 need to be encrypted, and it's still optional for those that upgrade.

Most people just stick with whatever default settings their stuff comes with, which is what makes default settings so important—almost all Android phones support encryption, but few actually use it. Assuming that people don't begin encrypting their Android phones en masse or that Google doesn't change its policies, it means that it could easily be another two or three years before even a plurality of Android devices are encrypted.

If you or someone you know has an older, unencrypted Android phone, when should it be encrypted? Obviously, if privacy and security trump all other concerns for you, you should encrypt regardless. But especially for more casual users with older or lower-end devices, encryption can noticeably impact performance in ways that can make these devices actively unpleasant to use. That's because data read from and written to the device's storage all needs to be decrypted and then re-encrypted, something that a lot of older ARM processors aren't particularly good at.

If you have a newer phone with a 64-bit ARM processor of recent vintage, it's much easier to justify enabling encryption even if your phone doesn't use 64-bit Android. That's because these processors use the ARMv8 instruction set, which among other things significantly improves performance for the constant decryption and encryption that happens when using encrypted storage. This storage benchmark from our review of the 2015 Moto E demonstrates the real-world benefits—the Moto E supports ARMv8 and the Moto G doesn't, and as a result, you lose much less performance when encrypting your storage.

You can figure out whether your phone includes ARMv8 by downloading one of several system information tools for Android, including both CPU-Z and AIDA64. Both can tell you the name and model number and CPU architecture of the processor you're using. Qualcomm's common ARMv8 SoCs include the Snapdragon 410 and newer, the Snapdragon 610 and newer, and the Snapdragon 808/810 and newer. Samsung's Exynos 7 and 8-series chips are all ARMv8. And if you see anything about "Cortex A72" or "A57" or "A53," you can rest easy since those are all common ARMv8 CPU architectures designed by ARM and used by chipmakers in their own designs.

Andrew Cunningham

Andrew Cunningham

Andrew Cunningham

Andrew Cunningham

AIDA64 can go one step further—open the CPU tab and scroll to the bottom to see if AES, SHA1, and SHA2 are marked as "supported." AES is an encryption standard and the other two are hash algorithms, and if they're marked as "supported" here it means your phone or tablet can be encrypted without impacting performance too much. If you're interesting in encrypting your device, we have a quick guide for you here.