scaling a table to fit an entire page

To declare some predefined width for your table, you can use the tabular* environment or, even better, the tabularx environment from the tabularx package. I would also suggest you to consider some changes to the table layout: 1) Don't use vertical rules. 2) Use the features provided by the booktabs package. Here's your table with some modifications:

\documentclass{book} \usepackage{booktabs} \usepackage{tabularx} \begin{document} \begin{table} \centering \caption{Table shows the commulative oxygen levels at 2 minute time intervals. The displacement is measured in \textbf{cm}} \begin{tabularx}{\textwidth}{@{}>{\bfseries}c*{9}{X}@{}} \toprule Treatment & \multicolumn{9}{c@{}}{\textbf{Time of reading (in min)}} \\ \cmidrule(l){2-10} & \textbf{0} & \textbf{2} & \textbf{4} & \textbf{6} & \textbf{8} & \textbf{10} & \textbf{12} & \textbf{14} & \textbf{16} \\ \cmidrule(r){1-1}\cmidrule(l){2-10} 1 & 0 & 0 & 0.5 & 0.7 & 0.9 & 0.9 & 1 & 1.2 & 1.8 \\ 2 & 0 & 0 & 0 & 0.1 & 0.1 & 0.1 & 0.1 & 0.2 & 0.5 \\ 3 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \bottomrule \end{tabularx}% \label{tab:addlabel}% \end{table}% \end{document} 

The tabularx package provides the tabularx environment that was built just for this purpose. The first argument is the width of the table.

Here is your table in a MWE

\documentclass{report} \usepackage{bigstrut} \usepackage{tabularx} \begin{document} \begin{table}[htbp] \centering \caption{Table shows the commulative oxygen levels at 2 minute time intervals. The displacement is measured in \textbf{cm}} \begin{tabularx}{\textwidth}{|r|X|X|X|X|X|X|X|X|X|} \cline{2-10} \multicolumn{1}{r|}{} & \multicolumn{9}{c|}{\textbf{Time of reading (in min)}} \\ \cline{2-10} \multicolumn{1}{r|}{} & \multicolumn{1}{r}{\textbf{0}} & \multicolumn{1}{r}{\textbf{2}} & \multicolumn{1}{r}{\textbf{4}} & \multicolumn{1}{r}{\textbf{6}} & \multicolumn{1}{r}{\textbf{8}} & \multicolumn{1}{r}{\textbf{10}} & \multicolumn{1}{r}{\textbf{12}} & \multicolumn{1}{r}{\textbf{14}} & \textbf{16} \bigstrut\\ \hline \hline \textbf{Treatment 1} & 0 & 0 & 0.5 & 0.7 & 0.9 & 0.9 & 1 & 1.2 & 1.8 \bigstrut\\ \hline \textbf{Treatment 2} & 0 & 0 & 0 & 0.1 & 0.1 & 0.1 & 0.1 & 0.2 & 0.5 \bigstrut\\ \hline \textbf{Treatment 3} & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \bigstrut\\ \hline \end{tabularx}% \label{tab:addlabel}% \end{table}% \end{document} 

You could use the tabular* environment instead of the tabular environment. The tabular* environment takes an extra argument, which you should set to \textwidth. Inside the environment's second argument, use the construct @\extracolsep{\fill}} to indicate that all intercolumn spaces should be augmented by \fill, which will make the entire environment take up the width of \textwidth.

I've taken the liberty of streamlining your code a bit in the following MWE. For instance, I've defined the contents of the first column to be typeset in bold automatically, saving some coding later on. The many \multicolumn commands in the table's second row aren't necessary, by the way. I've also dispensed with the vertical rules, as I believe they don't add appreciably to the table's intelligibility. Finally, I've used the commands \toprule, \cmidrule, \midrule, and \bottomrule of the booktabs package to get some well-spaced horizonal rules (in lieu of using \hline).

\documentclass{article} \usepackage{array,booktabs} \begin{document} \begin{table}[h] \caption{Table shows the commulative oxygen levels at 2 minute time intervals. The displacement is measured in \textbf{cm}} \label{tab:addlabel} \setlength\tabcolsep{0pt} % make LaTeX figure out optimal amount of intercol. whitespaced \begin{tabular*}{\textwidth}{@{\extracolsep{\fill}} >{\bfseries}l *{9}{l} } \toprule & \multicolumn{9}{c}{\textbf{Time of reading (in min)}} \\ \cmidrule{2-10} & \textbf{0} & \textbf{2} & \textbf{4} & \textbf{6} & \textbf{8} & \textbf{10} & \textbf{12} & \textbf{14} & \textbf{16} \\ \midrule Treatment 1 & 0{\phantom{.0}} & 0{\phantom{.0}} & 0.5 & 0.7 & 0.9 & 0.9 & 1 & 1.2 & 1.8 \\ Treatment 2 & 0 & 0 & 0 & 0.1 & 0.1 & 0.1 & 0.1 & 0.2 & 0.5 \\ Treatment 3 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \bottomrule \end{tabular*} \end{table} \end{document} 

I am writing a report and facing similar problem. I want to included a long table (spreading over many pages) in the appendix of the report. The tale contains around 100 columns but only four rows. I want to include maximum columns in a page. I am using the following latex command line. I would be grateful for a favorable consideration.

\begin{landscape} \setlength\LTleft{2pt} \setlength\LTright{2pt} \begin{table}[htbp] \caption*{} \begin{longtable}{|l|p{4in}|l|p{4in}|}\hline HS2&Description&HS2&Description \\ \hline 01&Live animals&20&Vegetable, fruit, nut, etc food preparations \\ \hline 02&Meat and edible meat offal&21&Miscellaneous edible preparations \\ \hline 03&Fish, crustaceans, molluscs, aquatic invertebrates nes&22&Beverages, spirits and vinegar \\ \hline 04&Dairy products, eggs, honey, edible animal product nes&23&Residues, wastes of food industry, animal fodder \\ \hline ... .... (up to 100 times) \end{longtable} \end{table} \end{landscape}