\documentclass[french,a4paper]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{tabularx}
\usepackage{booktabs}
\usepackage{babel}
\usepackage{subcaption}
\frenchsetup{AutoSpacePunctuation,ThinColonSpace,INGuillSpace,InnerGuillSingle,SuppressWarning} %espaces ?;:!«»
\begin{document}
\begin{table}
\centering
\begin{subtable}[b]{.45\linewidth}
\centering
\begin{tabularx}{\linewidth}{ccrrr}
\toprule
Dimensions & \multicolumn{2}{c}{Format} \\
\midrule
3952 × 1824 & 13:6 & 2.16667 \\
2340 × 1080 & 13:6 & 2.16667 \\
\midrule
3840 × 2160 & 16:9 & 1.77778 \\
2688 × 1512 & 16:9 & 1.77778 \\
640 × 360 & 16:9 & 1.77778 \\
\midrule
3264 × 2448 & 4:3 & 1.333 \\
3200 × 2400 & 4:3 & 1.333 \\
320 × 240 & 4:3 & 1.333 \\
240 × 320 & 4:3 & 1.333 \\
\midrule
2976 × 2976 & 1:1 & 1 \\
1080 × 1080 & 1:1 & 1 \\
\midrule
2880 × 2156 & 720:539 & \footnotesize{$1.3358$} \\
\midrule
3952 × 1824 & 13:6 & \footnotesize{$2.167$} \\
2340 × 1080 & 13:6 & \footnotesize{$2.167$} \\
\midrule
1280 × 768 & 5:3 & 1.6667 \\
800 × 480 & 5:3 & 1.6667 \\
\midrule
1024 × 738 & 512:369 & 1.3875 \\
Merci, il aurait du être entre les 2 tablaux!