HTML Guides for range

The <col> elements in this table declare more columns than the rows use, and no <td> or <th> begins in the reported range.

Each <col> inside a <colgroup> adds one column to the table, or as many columns as its span attribute says, so <col span="4"> declares four. The HTML table model requires every column to have at least one cell that starts in it. A cell that only crosses a column through colspan doesn't count. With <col span="4"> and rows made of <th colspan="4">, or of <td> followed by <td colspan="3">, cells start only in columns 1 and 2, and the validator reports columns 3 and 4 together as the range 3…4.

This often happens in layout tables that declare a fine grid in the <colgroup> and then merge those columns with colspan in every row. It also happens when the rows are shorter than the column markup, which adds a second error: "A table row was 2 columns wide, which is less than the column count established using column markup (4)". When only one column is empty, the validator names that single column ("Table column 4") instead of a range.

To fix it, declare only the columns the rows use. Remove <col> elements or lower their span, and reduce the colspan values to match. Deleting the <colgroup> alone isn't enough: the oversized colspan then creates the empty columns itself, and the validator reports them as established by th or td instead.

Invalid example

The <col> declares four columns, but cells start only in the first two:

<table>

<colgroup>

<col span="4">

</colgroup>

<tr>

<th colspan="4">Opening hours</th>

</tr>

<tr>

<td>Monday</td>

<td colspan="3">9:00 to 17:00</td>

</tr>

</table>

Valid example

Two columns in the <colgroup>, and a cell starts in each of them:

<table>

<colgroup>

<col class="day">

<col class="hours">

</colgroup>

<tr>

<th colspan="2">Opening hours</th>

</tr>

<tr>

<td>Monday</td>

<td>9:00 to 17:00</td>

</tr>

</table>

When a table cell uses colspan to span multiple columns, the HTML specification requires that the columns being spanned actually exist and are accounted for in the table's column structure. If a cell's colspan creates columns that no other row has cells beginning in, the validator flags those empty columns. For example, if your widest row has 3 columns but another row contains a cell with colspan="6", columns 4 through 6 are established by that cell but are essentially phantom columns — no cell in any other row starts in them.

This matters for several reasons. Screen readers and assistive technologies rely on a coherent table structure to navigate cells and announce column/row relationships. An inconsistent column count can confuse these tools, leading to a poor experience for users who depend on them. Browsers may render the table without visible errors, but the underlying structure is invalid, which can cause unpredictable layout behavior across different rendering engines.

How to Fix

1. Identify the offending row. Look for <td> or <th> elements whose colspan value creates more columns than the rest of the table defines.
2. Reduce the colspan value so it matches the actual number of columns in the table.
3. Alternatively, add cells to other rows if you genuinely need more columns — make sure every column has at least one cell that begins in it.

A good rule of thumb: the colspan of any cell, combined with its starting column position, should never exceed the total column count of the table.

Examples

Incorrect: colspan exceeds the table's column count

This table has 2 columns (established by the first row), but the second row's colspan="5" tries to span 5 columns. Columns 3 through 5 have no cells beginning in them in any row.

<table>

<tr>

<td>First</td>

<td>Second</td>

</tr>

<tr>

<td colspan="5">Spans too many columns</td>

</tr>

</table>

Correct: colspan matches the table's column count

Set the colspan to 2 so the cell spans exactly the columns that exist.

<table>

<tr>

<td>First</td>

<td>Second</td>

</tr>

<tr>

<td colspan="2">Spans both columns</td>

</tr>

</table>

Incorrect: mixed rows with mismatched column counts

Here the first row establishes 3 columns, but the second row creates a cell starting at column 1 that spans 5 columns, leaving columns 4 and 5 with no cells beginning in them.

<table>

<tr>

<td>A</td>

<td>B</td>

<td>C</td>

</tr>

<tr>

<td colspan="5">Too wide</td>

</tr>

</table>

Correct: expand the table or reduce the span

Option A: Reduce the colspan to match the existing 3 columns.

<table>

<tr>

<td>A</td>

<td>B</td>

<td>C</td>

</tr>

<tr>

<td colspan="3">Spans all three columns</td>

</tr>

</table>

Option B: If you truly need 5 columns, add cells to the other rows so every column has a cell beginning in it.

<table>

<tr>

<td>A</td>

<td>B</td>

<td>C</td>

<td>D</td>

<td>E</td>

</tr>

<tr>

<td colspan="5">Spans all five columns</td>

</tr>

</table>

A <th> with a colspan wider than the rest of the table adds the columns in the reported range, and no <td> or <th> begins in any of them.

The validator builds the table grid from each row's cells and their colspan values. A <th colspan="4"> that starts in column 2 covers columns 2 to 5, so the table has at least five columns. The HTML table model requires every column to have at least one cell that starts in it, and a cell that only crosses a column through colspan doesn't count. If the other rows have only two cells, nothing starts in columns 3 to 5, and the validator reports them as the range 3…5, naming th as the element that created them.

This often happens with header rows that group headings over more columns than the body has, or with a colspan left over from a wider version of the table. The short rows usually add a warning too: "A table row was 2 columns wide, which is less than the column count established by the first row (5)." When only one column is empty, the validator names that single column ("Table column 3") instead of a range.

To fix it, lower the colspan so the header covers only the columns the rows use. If the table really needs the extra columns, add cells to the other rows so a cell starts in each of them.

Invalid example

The second heading spans four columns, but each body row has only two cells:

<table>

<tr>

<th>Term</th>

<th colspan="4">Dates</th>

</tr>

<tr>

<td>Autumn</td>

<td>September to December</td>

</tr>

</table>

Valid example

Without the colspan, the header and the body both have two columns:

<table>

<tr>

<th>Term</th>

<th>Dates</th>

</tr>

<tr>

<td>Autumn</td>

<td>September to December</td>

</tr>

</table>