[Tex/LaTex] Two subfigures in two rows

subfloats

I would like to have two subfigures but on two rows. I tried with this code:

\documentclass[11pt,a4paper,titlepage]{report}  
\usepackage[T1]{fontenc}  
\usepackage[latin9]{inputenc}  
\usepackage{amssymb}  
\usepackage{graphicx}  
\usepackage{subcaption}  

\begin{document}  

\begin{figure}[h!]  
\centering  
\begin{subfigure}{.5\textwidth}  
  \centering  
  \includegraphics[width=1.8\linewidth]{image}  
    \caption{Caption for image 1}   
\end{subfigure}   

\begin{subfigure}{.5\textwidth}  
  \centering  
  \includegraphics[width=1.8\linewidth]{image}  
    \caption{Caption for image 2}   
\end{subfigure}  
\caption{A caption for both images}  
\end{figure}  
\end{document}

The result is: both figures are aligned to the right side of the page while the caption of each figure is still in the center.
Really appreciate if some one could help me!

Edit: Image of the result if this could help
enter image description here

Best Answer

Well, 1.8\linewidth is 80% too wide for the current block (which is .5\textwidth wide), causing a problem. Try using only \linewidth or at least some portion of it.

enter image description here

\documentclass{report}
\usepackage{graphicx,subcaption}
\begin{document}

\begin{figure}[ht]
  \centering
  \begin{subfigure}{\linewidth}
    \centering
    \includegraphics[width=.8\linewidth]{example-image-a}
    \caption{Caption for image 1}
  \end{subfigure}

  \begin{subfigure}{\linewidth}
    \centering
    \includegraphics[width=.8\linewidth]{example-image-b}
    \caption{Caption for image 2}
  \end{subfigure}  
  \caption{A caption for both images}  
\end{figure}  
\end{document}

Remember that \linewidth is a relative length. See Difference between \textwidth, \linewidth and \hsize.

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