Calibration SuiteSwitch Deadband Calculator
All calculatorsFree field tool

Instrument Technician Toolbox

Switch Deadband Calculator

Evaluate switch set point, reset point, deadband, direction, and tolerance.

1

Switch range

Enter the calibrated engineering range.

Span100.000 PSI
2

Observed operation

Enter the trip and reset values.

3

Allowed deadband

Choose how the maximum is specified.

Switch resultPASSDirection and deadband are acceptable
Calculated deadband3.000 PSI3.000% of span
Trip / set point75.000 PSI
Reset point72.000 PSI
Expected reset directionBelow trip point
Observed directionVALID
Maximum allowed deadband5.000 PSI
Deadband margin2.000 PSI

Equation guide

How pressure switch deadband is calculated

Switch deadband—also called differential—is the separation between the trip point and the reset point. It prevents rapid cycling when the process hovers near the set point. The required reset direction depends on whether the switch trips on a rising or falling process.

This tool evaluates both the numerical deadband and the physical operating direction. A small numerical difference cannot pass if the reset occurs on the wrong side of the trip point.

Deadband in engineering units

Deadband = |Trip point − Reset point|

The absolute value reports a positive differential in PSI, inH₂O, temperature, level, or the selected process unit.

Deadband as percent of span

Deadband % = Deadband ÷ (URV − LRV) × 100

Use the calibrated range, not the trip point, when the specification is stated as percent of span.

Maximum allowed deadband

Maximum = Span × Allowed % ÷ 100

When the specification is fixed in engineering units, the entered maximum is used without conversion.

Direction check

High-acting: Reset < Trip   |   Low-acting: Reset > Trip

Final pass requires the proper reset direction and an observed deadband at or below the maximum.

Worked example: high-acting pressure switch

A 0–100 PSI switch trips at 75 PSI and resets at 72 PSI. Its maximum allowed deadband is 5% of span.

Observed deadband|75 − 72| = 3 PSI
Allowed deadband100 × 5% = 5 PSI
ResultCorrect direction + 3 ≤ 5 → Pass

Switch deadband FAQs

Are deadband and hysteresis the same?

In many field procedures the terms are used interchangeably for the difference between operate and reset points. Manufacturer terminology can vary, so follow the device data sheet and approved procedure.

Why must a high-acting switch reset below its trip point?

After tripping on a rising input, the process must fall far enough to cross the separate reset threshold. The opposite relationship applies to a low-acting switch.

Should I use percent of range or percent of set point?

Use the exact basis stated in the specification. This calculator’s percent option is percent of calibrated span; choose fixed engineering units when the manufacturer provides a fixed differential.

Does this test prove the complete switch loop works?

No. A complete functional test may also require contact verification, control-system indication, alarm or trip action, wiring checks, and documentation under the applicable procedure.