Julio Lloret Lab

Electrochemistry

Reference electrode converter

Change the reference scale—not the chemistry. Specify the filling solution and conditions, or use a measured reference-to-reference calibration.

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Inputs & conditions

Scientific tool
Aqueous reference conditions
Activity-based pH; used only for RHE.
Tabulated offsets are limited to 25 °C.
Measured or documented at the entered temperature.
Measured or documented at the entered temperature.
Record the medium
Included in exported results; not used as an automatic activity or junction-potential correction.

Nominal, not calibrated. Fixed aqueous offsets exclude your unknown junction potential and electrode drift. ¹ The saturated-KCl preset uses +0.199 V from the cited table; other conventions use about +0.197 V. Use Custom for your measured value.

Results

SI-based

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Displayed digits are a numerical representation, not an experimental uncertainty estimate. Input conditions and method version are included in exports.

Reference conversion and calibration

A change of reference is an additive shift for the same working-electrode state. It does not predict how the chemistry changes when pH, electrolyte or solvent is changed. Define each reference offset as the potential of that reference versus SHE.

ESHE = Ein + Eref,in vs SHE
Eout = ESHE − Eref,out vs SHE
ERHE = ESHE + [ln(10) RT/F] × pH

The RHE relation assumes unit hydrogen fugacity (1 bar standard state). At 25 °C, its slope is about 59.1593 mV per pH unit. Temperature changes that term, but they also change real reference electrodes: this calculator therefore refuses tabulated Ag/AgCl or SCE offsets away from 25 °C. Choose a calibrated Custom offset at the actual temperature.

Worked example

−0.250 V vs Ag/AgCl (3 M KCl), pH 7, 25 °C:
ESHE = −0.040 V; ERHE ≈ +0.374115 V.

Nonaqueous / ferrocene mode

Measure E½(Fc⁺/Fc) against your laboratory reference in the same solvent, supporting electrolyte and experimental conditions. The calibrated mode subtracts this measured value for A → Fc; it adds it for the inverse transformation. No universal Fc⁺/Fc-to-SHE offset is assumed.

Evs B = Evs A − E½(B vs A)

Common questions

Why is saturated Ag/AgCl shown as +0.199 V, not +0.197 V?

The bundled table uses the +0.199 V saturated-KCl convention in the cited ACS Omega table. Published tabulations differ by a few millivolts. For your electrode, select Custom and use a documented or calibrated value; the label “Ag/AgCl” alone does not specify the reference potential.

Where are Hg/HgO and other reference electrodes?

Use Custom with the offset measured for the actual filling solution and temperature. In particular, do not replace a calibrated Hg/HgO potential by a universal number while changing hydroxide concentration. Nonaqueous reference-pair shifts should use the calibrated mode rather than an assumed bridge to SHE.

Sources and conventions

  1. IUPAC Gold Book · Nernst equation
  2. ACS Omega (2021) · Reference-potential conventions, Table 2
  3. Gamry Instruments · Reference electrodes and nonaqueous calibration

Method version 1.0.0 · 19 September 2026. Display precision is not measurement accuracy. Read the full scope and validation limits.