# How to add space between column labels?

I want to add some space between column labels States, Inputs and Outputs. Now they are very close so it doesn't look good. What can I do to add some space?

\documentclass[12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{float}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{algorithm}
\usepackage{graphicx}
\usepackage{rotating,booktabs,multirow}

\usepackage[T1]{fontenc}
\usepackage{fix-cm}
\setlength{\tabcolsep}{0.7pt}

\begin{table*}[t]
\centering
\begin{tabular}{c c c c c c c c}
\midrule
\multicolumn{3}{c}{} & \multicolumn{2}{c}{Freezed } &\multicolumn{2}{c}{Solid SF} \\
\cmidrule(r){4-7}
States & Inputs & Outputs & Length & Time & Length & Time \\
\cmidrule(r){1-4}\cmidrule(l){4-7}
\multirow{1}{*}{4096}& 2 &  2 & 21.47 & 63327.2 & 21.62 & 52520.84 \\
\midrule
\bottomrule
\end{tabular}

\caption{Averages of experiments}
\label{tab:t3}
\end{table*}
\end{document}

• Please help us help you and add a minimal working example (MWE) that illustrates your problem instead of just a code snippet. Reproducing the problem and finding out what the issue is will be much easier when we see compilable code, starting with \documentclass{...} and ending with \end{document}. – albert Aug 5 '18 at 16:24
• I think, I added a working one. – Goju Aug 5 '18 at 16:31

Do not modify \tabcolsep

 %\setlength{\tabcolsep}{0.7pt}


it makes no sense with such a small space.

• Actually, that stands for the previous table. – Goju Aug 5 '18 at 16:41

mostly off-topic (since main problem is solved by Herbert answer) however i see in table's code more issues. i would to alter it as follows:

\documentclass[12pt]{article}
%\usepackage[utf8]{inputenc} % now id default
\usepackage[T1]{fontenc}
\usepackage{fix-cm}
\usepackage{float}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{algorithm}
\usepackage{graphicx}

\usepackage{booktabs, multirow, rotating}

\begin{document}
\begin{table*}[t]
\centering
\begin{tabular}{c c c c c c c c}
\toprule
\multicolumn{3}{c}{} & \multicolumn{2}{c}{Freezed} & \multicolumn{2}{c}{Solid SF} \\
\cmidrule(r){4-5}\cmidrule(l){6-7}
States & Inputs & Outputs & Length & Time & Length & Time \\
\midrule
4096    & 2 & 2 & 21.47 & 63327.2 & 21.62 & 52520.84 \\
\bottomrule
\end{tabular}

\caption{Averages of experiments}
\label{tab:t3}
\end{table*}
\end{document}


in case, that your table will have more (many) rows, you should consider to use the S column type which enable align numbers at decimal points:

 ...
\usepackage {siunitx}
...

\begin{document}
\begin{table*}[t]
\centering
\begin{tabular}{c cc S[table-format=2.2]
S[table-format=5.1]
S[table-format=2.2]
S[table-format=5.2]
}
\toprule
\multicolumn{3}{c}{} & \multicolumn{2}{c}{Freezed} & \multicolumn{2}{c}{Solid SF} \\
\cmidrule(r){4-5}\cmidrule(l){6-7} % changed
States & Inputs & Outputs & {Length} & {Time} & {Length} & {Time}      \\
\midrule
4096    & 2      & 2       & 21.47   & 63327.2 & 21.62    & 52520.84    \\
\bottomrule
\end{tabular}