INSTRUMENTATION
Find the expected linear loop signal for a given process value.
Enter your values, then select Calculate.
mA = 4 + 16 × (PV − LRV) / (URV − LRV).
Linear scaling only. Values outside the configured range are extrapolated, not clamped. The result does not represent the physical output limits of a transmitter.
Calculation reviewed: 4 October 2026 · Engineering Desk Tools
Find the expected linear loop signal for a given process value. Start with measurements or documented values for the equipment and reporting period you actually want to assess. The calculator does not fill in a typical installation for you. Its blank fields help keep a demonstration value from being mistaken for your own operating data.
Choose the required options, enter the values in the labelled units and select Calculate. If a field is rejected, check its range and unit before changing it. The result is accompanied by the equation and assumptions so you can decide whether it answers your engineering question.
Record the measurement source and operating condition. Retain unrounded values for verification.
This inverse calculation is useful when planning loop checks. Enter an engineering value to find the expected transmitter current, then compare that expected current with a measured or simulated value. It does not command a physical output and cannot determine transmitter saturation or diagnostic thresholds without the device documentation.
mA = 4 + 16 × (PV − LRV) / (URV − LRV).
Linear scaling only. Values outside the configured range are extrapolated, not clamped. The result does not represent the physical output limits of a transmitter.
This example does not populate the form. Enter your own installation data.
| Input | Example value |
|---|---|
| Process value | 50 |
| Lower range value (at 4 mA) | 0 |
| Upper range value (at 20 mA) | 100 |
Calculated result: 12 mA. Expected linear loop current
Check the arithmetic independently using the displayed equation. Retain intermediate precision and compare the final value with your equipment documentation.
| Changed input | Calculated result |
|---|---|
| Process value: 25 | 8 mA |
| Process value: 50 | 12 mA |
| Process value: 75 | 16 mA |
These illustrative rows retain the worked example assumptions except for the varied input. They are not certified ratings or manufacturer data. Use the form for intermediate values.
Swapping the lower and upper endpoints; assuming extrapolated current will be produced by the device; mixing units between the process value and the range. Before relying on the output, check the decimal format, unit scale and source of each value. Recheck unusual results against the formula.
No. Inputs remain blank when the tool opens or when you clear them. The worked example and table are reading material below the calculator. Enter the actual values you want to check each time, and label saved reports so their context is not lost.
The result is the current a linear transmitter should produce for the process value entered. Compare it with a simulated or measured loop current to check the range and wiring.
The allowed range follows the meaning of each input. A divisor needs a positive value; other fields may allow zero. Engineering range endpoints may be negative. A rejected input must be corrected before a result can be shown.
No. Linear scaling only. Values outside the configured range are extrapolated, not clamped. The result does not represent the physical output limits of a transmitter. Use the calculation as support for a checked decision, and review equipment documentation and applicable requirements before changing an installation or operating setting.
Calculate first, then use Copy result or Print report. Some maintenance tools also provide a CSV summary. Reports contain your own entered data, so review them before sharing. You can share the public page URL without including plant records or confidential measurements.
Use the Contact page and include the tool URL, input values, units, expected output and the reference you used. Explain the measurement basis. Exclude confidential information.
Use related calculations with consistent units, periods and equipment scope.