How to Check CPU Temperature on Raspberry Pi Quickly

To check the CPU temperature on a Raspberry Pi, use the command vcgencmd measure_temp in the terminal. Alternatively, you can read the temperature in Python by running temp = float(open('/sys/class/thermal/thermal_zone0/temp').read()) / 1000 to get the temperature in Celsius.

Syntax

The main ways to check CPU temperature on Raspberry Pi are:

• vcgencmd measure_temp: Runs a system command to get the temperature.
• Reading from /sys/class/thermal/thermal_zone0/temp: Reads a system file that contains the temperature in millidegrees Celsius.

In Python, you open the file, read the value, and divide by 1000 to convert to degrees Celsius.

bash/python

vcgencmd measure_temp

# Python syntax to read temperature
with open('/sys/class/thermal/thermal_zone0/temp') as f:
    temp = float(f.read()) / 1000
    print(f"CPU Temperature: {temp}°C")

Example

This example shows how to check the CPU temperature using Python. It reads the temperature file, converts the value, and prints it.

python

with open('/sys/class/thermal/thermal_zone0/temp') as f:
    temp = float(f.read()) / 1000
print(f"CPU Temperature: {temp:.2f}°C")

Output

CPU Temperature: 45.32°C

Common Pitfalls

Common mistakes when checking CPU temperature on Raspberry Pi include:

• Trying to run vcgencmd without it installed or on unsupported devices.
• Not dividing the raw temperature value by 1000 when reading from the system file, resulting in a very large number.
• Running the commands without proper permissions, which can cause errors.

python

## Wrong way (no division):
with open('/sys/class/thermal/thermal_zone0/temp') as f:
    temp = float(f.read())
print(f"Wrong CPU Temperature: {temp} (too large)")

## Right way:
with open('/sys/class/thermal/thermal_zone0/temp') as f:
    temp = float(f.read()) / 1000
print(f"Correct CPU Temperature: {temp}°C")

Output

Wrong CPU Temperature: 45320.0 (too large)
Correct CPU Temperature: 45.32°C

Quick Reference

Summary tips for checking CPU temperature on Raspberry Pi:

• Use vcgencmd measure_temp for a quick terminal check.
• Read /sys/class/thermal/thermal_zone0/temp for programmatic access.
• Always divide the raw value by 1000 to get Celsius degrees.
• Run commands with appropriate permissions.

Key Takeaways

Use the command vcgencmd measure_temp to quickly check CPU temperature in the terminal.

Read the file /sys/class/thermal/thermal_zone0/temp and divide by 1000 to get temperature in Celsius.

In Python, open the temperature file, convert the value, and print it for monitoring.

Avoid forgetting to divide the raw temperature value by 1000 to prevent incorrect readings.

Ensure you have proper permissions to run commands or read system files.