I am using siunitx in "per-mode=symbol", and that is working very well. However now I have run into an isolated case, where I need the "per"-symbol to be ^{-1}. Here is a MWE showing what I desire:


\usepackage{amsmath, amsthm, amssymb}

\noindent A speed of $v=\SI{888}{\meter\per\second}$, this is fine. \\
\noindent A lifetime of $\Gamma=\SI{888}{\per\second}$, not OK. It should be 888 s$^{-1}$.


Is there a way to define for a single "instance" that it should not use per-mode=symbol?

  • 2
    Do you mean for all \per\second cases or just this specific one given?
    – Joseph Wright
    Oct 27 '12 at 17:36
  • Just this specific one.
    – BillyJean
    Oct 27 '12 at 17:40
  • 3
    Perhaps $\Gamma=\SI[per-mode=reciprocal]{888}{\per\second}$? Oct 27 '12 at 17:40
  • 1
    You could also write it literally as $\Gamma = \SI{888}{s^{-1}}$ (or {\second^{-1}}) but Paulo Cereda's/Joseph Wright's form is preferred. Oct 27 '12 at 18:23

The siunitx commands all take a first optional argument to apply settings locally. Thus you want



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