Instrumentation
Sensor Percent Span / Range Calculator
Percent of span expresses where a process value falls within an instrument's calibrated range (LRV to URV). This is a general-purpose span calculator — it is separate from the 4–20 mA calculator and does not include signal conversion. Enter any engineering unit range and process value to find the percent of span, or enter a percent to find the corresponding process value.
TypeInteractive calculator — separate from unit conversions
Calculator
kPa
kPa
kPa
Result
Percent span25 %
Formulas
Percent span from PV
% span = (PV − LRV) / (URV − LRV) × 100
PV from percent span
PV = LRV + (% span / 100) × (URV − LRV)
Diagram
Worked example
A pressure transmitter is ranged 0–100 kPa (LRV = 0, URV = 100). The process value reads 25 kPa. What is the percent span?
- 01% span = (PV − LRV) / (URV − LRV) × 100
- 02% span = (25 − 0) / (100 − 0) × 100
- 03% span = 25%
Result
The process value is at 25% of span.
FAQ
How is this different from the 4–20 mA calculator?
The 4–20 mA calculator converts between a milliamp signal and a process value. This calculator works directly with process values and percent span without any signal conversion.
Does this handle square-root extraction?
No. Square-root extraction (common for DP flow transmitters) is not implemented. The relationship is always linear.
What happens if my value is outside the LRV–URV range?
The calculator will still produce a result, but it will be flagged as out of range (below 0% or above 100%). This may indicate an over-range condition or incorrect range settings.
Does the engineering unit label affect the calculation?
No. The engineering unit label is for display only. No unit conversion is applied — all values must be in the same unit.