How to calculate the total width of a (tabularray) table and pass this length to other packages such tikz or tcolorbox?

Please consider the following code. It produces a table using tabularray which has fixed width columns, so its total width is smaller than \textwidth. How can find out what the total width of the table is, so I can pass this length to other packages such as tikz or tcolorbox and create a picture or a box with exactly the same width as the table? Please note that the box created, in the exable below, by tcolorbox is slightly at the left, why? Can be fixed? And also is slightly smaller than the rectangle created by tikz although they have virtually the same width, 15cm.

\documentclass[12pt]{article}
\usepackage[a4paper, total={180mm,257mm},left=15mm,top=20mm]{geometry}
\usepackage{tabularray}
\usepackage{tikz,tcolorbox,blindtext}

\begin{document}
\begin{tblr}{colspec={Q[3.2cm,c]Q[5.2cm,c]Q[5.2cm,c]},rows={0.8cm,m},vlines,hlines}
Column 1    & Column 2 & Column 3 \\
A11         &   A12    &     A13  \\
A221        &   A22    &     A23  \\
\end{tblr}

\vspace{10pt}

\begin{tikzpicture}
\draw (0,0) rectangle (15,4);
\end{tikzpicture}

\begin{tcolorbox}[width=15cm]
\blindtext[1]
\end{tcolorbox}
\end{document}


• You could use the \settowidth macro to measure the width of your table. To avoid having to code the table twice, you could use a savebox and use it once to typeset your table and another time to measure the width.

• The tcolorbox is not shifted to the left, instead everything else is shifted to the right from the normal paragraph indent of the class you use. You can avoid it locally by using \noindent or globally by changing the parindent length

\documentclass[12pt]{article}
\usepackage[a4paper, total={180mm,257mm},left=15mm,top=20mm]{geometry}
\usepackage{tabularray}
\usepackage{tikz,tcolorbox,blindtext}

\newlength{\foo}
\newsavebox{\mybox}

\begin{document}

\savebox{\mybox}{\begin{tblr}{colspec={Q[3.2cm,c]Q[5.2cm,c]Q[5.2cm,c]},rows={0.8cm,m},vlines,hlines}
Column 1    & Column 2 & Column 3 \\
A11         &   A12    &     A13  \\
A221        &   A22    &     A23  \\
\end{tblr}}

\noindent\usebox{\mybox}

\settowidth{\foo}{\usebox{\mybox}}

\noindent\rule{\foo}{1pt}

\vspace{10pt}

\noindent\begin{tikzpicture}
\draw (0,0) rectangle (\foo,4);
\end{tikzpicture}

\begin{tcolorbox}[width=\foo]
\blindtext[1]
\end{tcolorbox}
\end{document}


• How can handle the way you suggested me so I can make my boxes, tables etc have all the same width with a table or a box that is not the first one in my document, but second, third, etc? I tried with no succeed. If is the first one I measure its width works fine and thank you. So I need to measure the width say of the fifth table and copy this width also to the previous four boxes, tables. Jan 23 at 12:46
• Have a look at the totcount package. You could use it store the width of your table in the aux file and reuse it for further compilations. Jan 23 at 12:47
• ... or you could define the box of the table at the start of the document, measure it, use the width for whatever you like and then use the box to insert the table sometime later in the document Jan 23 at 12:50