How many apps can be installed in 512mb RAM Android phone?

A 512MB Android Phone will have 8 GB as maximum internal storage. Most of the time 512 MB RAM phone will comes with 2 or 4 or 8 GB variants. However, the user usable storage will be 1GB less than the storage mentioned in specification. For example, in Samsung Galaxy Star the storage mentioned in specification is 4GB but I had only 3.2 GB usable.

How much space do I have to install apps?

A typical user will occupy 2GB of space in music, videos, documents and miscellaneous stuffs. So you will be left with 1 - 2 GB to install apps in 4GB mobile. It will be 4GB max for phone with 8GB internal storage.

How many app I can install?

You can install as much as 55 apps in your phone. But it is not sure whether it will slow down your phone. The phone lagness is purely dependant on the type of app you install but not on the number of apps. Some apps runs 24 * 7 in the background. Apps like task killer, battery monitor, memory management needs to run every time to do the task.

What type of app is safe to install in 512 MB RAM phone?

• Choose your app by size - I always install apps with size less than 10MB to make sure my phone doesn't get lag.
• Don't install system apps - System apps are which monitors system resources. Few examples are battery monitor app and RAM management app. RAM management app kill the app that utilize more resource. It will kill the apps that is designed to run 24 * 7. If it kills such apps, again it will re-launch. So it will be a endless loop and just degrade the performance.
• Install apps developed by good developer - App speed is fully dependant on the developer. You don't have to blame your phone if few apps are slow. Take WhatsApp, this app run 24 * 7, app size is 38 MB even it runs smoothly. The reason is the app is bugless.