HTML Table Sizes
HTML tables can have different sizes for each column, row, or the entire table.

HTML Table Width
To set the width of a table, add the style
attribute to the <table>
element:
Set the width of the table to 100%:
<table style="width:100%">
<tr>
<th>Firstname</th>
<th>Lastname</th>
<th>Age</th>
</tr>
<tr>
<td>Sumit</td>
<td>Kumar</td>
<td>20</td>
</tr>
<tr>
<td>Amit</td>
<td>Yadav</td>
<td>18</td>
</tr>
</table>
Note: Using a percentage as the size unit for width specifies how wide this element will be compared to its parent element, which in this case is the <body>
element.
HTML Table Column Width

To set the size of a specific column, add the style attribute on a <th>
or <td>
element:
Set the width of the first column to 70%:
<table style="width:100%">
<tr>
<th style="width:70%">Firstname</th>
<th>Lastname</th>
<th>Age</th>
</tr>
<tr>
<td>Sumit</td>
<td>Kumar</td>
<td>20</td>
</tr>
<tr>
<td>Amit</td>
<td>Yadav</td>
<td>18</td>
</tr>
</table>
HTML Table Row Height

To set the height of a specific row, add the style
attribute on a table row element:
Set the height of the second row to 200 pixels:
<table style="width:100%">
<tr>
<th>Firstname</th>
<th>Lastname</th>
<th>Age</th>
</tr>
<tr style="height:200px">
<td>Sumit</td>
<td>Kumar</td>
<td>20</td>
</tr>
<tr>
<td>Amit</td>
<td>Yadav</td>
<td>18</td>
</tr>
</table>
Rowspan
and Colspan
Attributes
Rowspan
: If you want a table cell to span multiple rows, use the rowspan
attribute.
<td rowspan="2">
Colspan
: If you want a table cell to span multiple columns, use the colspan
attribute.
<td colspan="2">
Rowspan and Colspan in HTML Tables
Example for Colspan:
<table border>
<tr>
<td colspan="2">Merged Columns</td>
</tr>
<tr>
<td>Column 1</td>
<td>Column 2</td>
</tr>
</table>
Example for Rowspan:
<table border>
<tr>
<td>Row 1, Column 1</td>
<td rowspan="2">Merged Rows</td>
</tr>
<tr>
<td>Row 2, Column 1</td>
</tr>
</table>