Increase width of tabularx column

Question

Community,

I want to increase the width of a column because the text in the second row makes a new line. When I use p{x.xcm} there is no more centering of the content below.

Here is my code:

\begin{tabularx}{\textwidth}{
 l
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering}X
>{\centering\arraybackslash}X
}
   \toprule
   \multicolumn{1}{c}{\multirow{2}{*}[-0.5ex]{Probe}} & \multicolumn{2}{c}{Brechungsindex} & 
   \multicolumn{3}{c}{Volumen/mL} & \multicolumn{3}{c}{Masse/g} & \multicolumn{3}{c}{Stoffmenge/mol} 
   & \multicolumn{3}{c}{vol\%} & \multicolumn{3}{c}{mol\%}\\
   \cmidrule{2-18}
   & A-reich & B-reich & A & B & C & A & B & C & A & B & C & A & B & C & A & B & C\\
   \midrule
   P1 & 1.4242 & 1.4242 & 42   & 42   & 42   & 42    & 42   & 42 & 42    & 42   & 42 & 42  & 42 & 42 
   & 42  & 42 & 42\\
   P3 & 1.4242 & 1.4242 & 42   & 42   & 42   & 42    & 42   & 42 & 42    & 42   & 42 & 42  & 42 & 42 
   & 42  & 42 & 42\\
  \bottomrule
\end{tabularx}

The table is also in a sideways environment because it is so large.

Thank you in advance.

Greetings FH

Answer 1

Here is my suggestion based on tabular* instead of tabularx.

Depending on the contents of the columns, you might want to consider using siunitx in order to align the numbers with respect to their decimal separator. siunitx also comes in handy for the units in your column headers.

\documentclass{article}
\usepackage{tabularx}
\usepackage{booktabs}
\usepackage{rotating}
\begin{document}

\begin{sidewaystable}

\begin{tabular*}{\textwidth}{@{\extracolsep{\fill}}l*{17}{c}}
   \toprule
   Probe 
     & \multicolumn{2}{c}{Brechungsindex} 
       & \multicolumn{3}{c}{Volumen/mL} 
         & \multicolumn{3}{c}{Masse/g} 
           & \multicolumn{3}{c}{Stoffmenge/mol} 
             & \multicolumn{3}{c}{vol\%} 
               & \multicolumn{3}{c}{mol\%}\\
   \cmidrule(r){2-3} \cmidrule(lr){4-6} \cmidrule(lr){7-9} \cmidrule(lr){10-12} \cmidrule(lr){13-15} \cmidrule(l){16-18}
   & A-reich & B-reich & A & B & C & A & B & C & A & B & C & A & B & C & A & B & C\\
   \midrule
   P1 & 1.4242 & 1.4242 & 42   & 42   & 42   & 42    & 42   & 42 & 42    & 42   & 42 & 42  & 42 & 42 
   & 42  & 42 & 42\\
   P3 & 1.4242 & 1.4242 & 42   & 42   & 42   & 42    & 42   & 42 & 42    & 42   & 42 & 42  & 42 & 42 
   & 42  & 42 & 42\\
  \bottomrule
\end{tabular*}

\end{sidewaystable}
\end{document}

Answer 2

As Wulle suggested: replacing the first two >{\centering} with c did the job.

Thank you Wulle