Resistor tolerance
= Resistor tolerance
<Resistor tolerance> specifies the permissible manufacturing deviation of a <resistor>'s <electrical resistance> from its nominal value under stated conditions. For nominal <electrical resistance> $R_{\mathrm{nom}}>0$ and fractional <resistor tolerance> $0\le\tau<1$, the specified range is $R_{\mathrm{nom}}(1-\tau)\le R\le R_{\mathrm{nom}}(1+\tau)$. This differs from <measurement uncertainty>: <resistor tolerance> describes a component specification, while <measurement uncertainty> describes knowledge of a measured value; the tolerance alone is not a <probability distribution> for that value.
Two nominally equal <resistors> can have different actual <electrical resistances>, changing their <voltage divider> ratio even without an external <electrical load>. In a <loaded voltage divider>, use the actual <electrical resistances> to calculate both the unloaded output and the <Thévenin resistance> governing <voltage divider loading error>. A mismatch from <resistor tolerance> and a change from <voltmeter loading> are distinct effects that can occur together.