IEC 60359: Electrical Measuring Instruments — DMM Accuracy Classes and Error Expression

DMM “0.05% Accuracy” — Reading Error + Range Error Explained

IEC 60359:2001 specifies accuracy expression for electrical instruments. DMM accuracy = reading% + range%. Example: ±(0.05%rdg+0.01%rng) on 10V range at 5V = ±3.5mV.

The “+N digits” term dominates total error at low end of range. Always select range where reading falls in upper 60-100%.

TNLab — DMM accuracy combines reading% + range% — the latter dominates near range low end.