how to check ram in linux?

January 5, 2026

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Determine system RAM without physical inspection using command line tools. This method works for scripting and remote system administration when memory capacity is unknown.

Requirements

Linux system with terminal access
Basic command line knowledge
Root privileges for certain commands

Check RAM in Linux

Using the free Command

Run the following command to display memory usage:

$ free -h

The output shows total, used, and available memory:

              total        used        free      shared  buff/cache   available
Mem:           15Gi       2.1Gi       10Gi       421Mi       3.2Gi        12Gi
Swap:            0B          0B          0B

The total column displays installed RAM. Use -m for megabytes or -g for gigabytes.

Tip: Add -w flag to separate buffers and cache into distinct columns for detailed analysis.

Using /proc/meminfo

Read memory information directly from the system file:

$ grep MemTotal /proc/meminfo

The command returns:

MemTotal:       16384000 kB

This value represents total physical memory in kilobytes.

Note: The /proc/meminfo file contains real-time system statistics and updates dynamically.

Using vmstat Command

Display memory statistics with vmstat:

$ vmstat -s

Find the total memory line in the output:

      16384000 K total memory
       2195456 K used memory
       3276800 K active memory

Extract only total memory with grep:

$ vmstat -s | grep 'total memory'

Using top Command

Launch the interactive process viewer:

$ top

View memory statistics in the header section:

MiB Mem :  16000.0 total,  10234.5 free,   2100.3 used,   3665.2 buff/cache

Press q to exit top.

Tip: Press E in top to cycle through memory unit displays (KiB, MiB, GiB, TiB).

Using dmidecode Command

Access detailed hardware information with root privileges:

# dmidecode -t memory | grep Size

The output displays physical memory module details:

Size: 8192 MB
Size: 8192 MB
Size: No Module Installed
Size: No Module Installed

This shows installed RAM modules and empty slots.

Warning: The dmidecode command requires root access. Use sudo if not logged in as root.

Using lshw Command

Generate comprehensive hardware information:

# lshw -short -C memory

View memory class devices and capacity:

H/W path           Device      Class       Description
======================================================
/0/0                           memory      64KiB BIOS
/0/1                           memory      16GiB System Memory
/0/1/0                         memory      8GiB DIMM DDR4 2400 MHz
/0/1/1                         memory      8GiB DIMM DDR4 2400 MHz

Filter for system memory total:

# lshw -C memory | grep size

Comparing RAM Check Methods

Command	Detail Level	Root Required	Best For
`free`	Basic	No	Quick memory check
`/proc/meminfo`	Detailed	No	Scripting and automation
`vmstat`	Moderate	No	Memory statistics
`top`	Real-time	No	Live monitoring
`dmidecode`	Hardware	Yes	Physical module info
`lshw`	Hardware	Yes	Complete hardware scan

FAQS

How do I check RAM in Linux without root access?

Use free -h or cat /proc/meminfo commands. Both display total RAM without requiring root privileges for system administration.

What is the fastest way to check total RAM in Linux?

Run free -h for immediate results. The command displays total memory in human-readable format within seconds across all distributions.

How can I see physical RAM modules installed in Linux?

Execute sudo dmidecode -t memory to view detailed information about installed RAM modules including size, speed, and slot configuration.

Does free command show RAM speed and type?

No, free only displays memory capacity and usage. Use dmidecode or lshw commands to check RAM speed and type.

How to check RAM usage in Linux continuously?

Use top or htop commands for real-time monitoring. Both update memory statistics automatically and display process-level RAM consumption continuously.