Years back, smartphones require less memory in running their apps. These days, most smartphones run much-sophisticated apps that require higher Random Access Memory (RAM) – for better performance.
The Apple iPhone has greatly improved since its first generation model. New iPhone applications and features certainly require bigger RAM. Here are iPhone’s RAM sizes in each generation.

iPhone 4 RAM

The present iPhone generation, the iPhone 4, is equipped with 512 RAM. Most recent iPhone rivals though have bigger RAM, sizing up to 1GB. It is expected that the next iPhone will have two times RAM compared to the iPhone 4.

iPhone 3GS Memory

The iPhone that precedes the iPhone 4 has 256 MB of RAM. This amount seems pretty obsolete these days. Smartphone apps are becoming memory hungry beasts!

iPhone 3G RAM

Although it seems to be a close clone of the iPhone 3GS, the iPhone 3G lags behind the iPhone 3GS when it comes to some hardware specs, like CPU speed, camera, and of course the RAM size.
The iPhone 3G comes with 128 MB of RAM – half of the iPhone 3GS’.

iPhone (Original) RAM

The first generation iPhone has the same amount of RAM with its descendant, the iPhone 3G. It has 128 MB of RAM alike.

iPhone 4G RAM

Comparison Chart

iPhone 4 iPhone 3GS iPhone 3G iPhone (original)
RAM 512 Megabytes 256 Megabytes 128 Megabytes 128 Megabytes