How to Check Memory Usage on Raspberry Pi Quickly

To check memory usage on a Raspberry Pi, use the free -h command to see total, used, and free memory in a human-readable format. For real-time monitoring, top or htop commands provide dynamic views of memory and CPU usage.

Syntax

Here are common commands to check memory usage on Raspberry Pi:

• free -h: Shows total, used, free, and available memory in human-readable form.
• top: Displays real-time system processes and memory usage.
• vmstat: Reports virtual memory statistics.

bash

free -h

top

vmstat 1 5

Example

This example uses free -h to display memory usage in a clear format.

bash

free -h

Output

              total        used        free      shared  buff/cache   available
Mem:          3.8Gi       1.2Gi       1.5Gi       100Mi       1.1Gi       2.3Gi
Swap:         100Mi          0B       100Mi

Common Pitfalls

Some common mistakes when checking memory on Raspberry Pi:

• Using free without -h shows bytes, which is hard to read.
• Confusing cached and buffered memory as used memory; Linux uses free memory for cache to speed up processes.
• Not running top or htop with proper permissions may hide some details.

bash

free

# Better way:
free -h

Quick Reference

Command	Description
free -h	Show memory usage in human-readable format
top	Real-time system and memory usage display
htop	Enhanced interactive process viewer (install first)
vmstat 1 5	Show virtual memory stats every second for 5 times

Key Takeaways

Use free -h for a quick, readable summary of memory usage.

Run top or htop to monitor memory and CPU in real time.

Remember Linux uses free memory for cache; check 'available' memory for true free space.

Add -h to commands like free to see sizes in MB/GB instead of bytes.

Install htop with sudo apt install htop for a user-friendly interface.