How to Merge Cells in LaTeX Tables (multicolumn & multirow)

Merging cells in LaTeX tables is one of the most asked-about topics on r/LaTeX. The two commands you need are \\multicolumn (horizontal merge) and \\multirow (vertical merge).

Horizontal merge: \\multicolumn

Spans multiple columns into one cell:

\\begin{tabular}{lccc}
    \\toprule
    & \\multicolumn{3}{c}{Metrics} \\\\
    \\cmidrule(lr){2-4}
    Model & Precision & Recall & F1 \\\\
    \\midrule
    BERT & 0.89 & 0.85 & 0.87 \\\\
    GPT  & 0.91 & 0.88 & 0.90 \\\\
    \\bottomrule
\\end{tabular}

Syntax: \\multicolumn{NUM_COLS}{ALIGNMENT}{CONTENT}

Vertical merge: \\multirow

Spans multiple rows. Requires \\usepackage{multirow}:

\\usepackage{multirow}

\\begin{tabular}{llcc}
    \\toprule
    Category & Model & Acc & F1 \\\\
    \\midrule
    \\multirow{2}{*}{Small} & DistilBERT & 0.82 & 0.80 \\\\
                            & TinyBERT   & 0.79 & 0.77 \\\\
    \\midrule
    \\multirow{2}{*}{Large} & BERT-base  & 0.89 & 0.87 \\\\
                            & RoBERTa    & 0.91 & 0.90 \\\\
    \\bottomrule
\\end{tabular}

Syntax: \\multirow{NUM_ROWS}{WIDTH}{CONTENT} — use * for auto width.

Combining both

You can nest \\multicolumn inside \\multirow for complex headers:

\\multicolumn{2}{c}{\\multirow{2}{*}{Combined Header}} \\\\
\\multicolumn{2}{c}{} \\\\ % empty row for the multirow span

Common mistakes

• Forgetting \\cmidrule — use \\cmidrule(lr){2-4} instead of \\hline under merged headers
• Wrong column count — merged cells still consume column slots; leave cells empty with &
• Missing package — \\multirow requires \\usepackage{multirow}

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