Range vs Span – A Fundamental Instrumentation Concept

Understanding the difference between Range and Span is essential for selecting, calibrating, and troubleshooting industrial instruments.

Range = Minimum value to Maximum value an instrument can measure

Span = Difference between Maximum and Minimum values

Example:

Pressure Transmitter Range: 0–10 bar

Range = 0 to 10 bar

Span = 10 bar

Temperature Transmitter Range: 50°C–150°C

Range = 50°C to 150°C

Span = 100°C

Knowing these concepts helps engineers configure instruments correctly, improve measurement accuracy, and ensure reliable process control.

What is the span of a transmitter with a range of 4 to 20 mA? Share your answer in the comments!