How to fill blank cells in a table
Fill Blank Cells reads table data from Table data or a CSV, TSV, or TXT file. You decide which cells qualify as blank, then choose a fill rule for each checked column. The page applies those rules in the browser and updates Preview and Change log before you use Export CSV.
How to use Fill Blank Cells
- Paste data into Table data, or use browse files to load a CSV, TSV, or TXT file.
- Set First row is a header, then choose the blank settings.
- Under Per-column fill rules, check a column, choose a rule, and set its parameters.
- Review the summary, Preview, and Change log as the result updates.
- Use Export CSV for the filled table or the recorded changes.
What counts as a blank cell
Treat empty string as blank matches empty fields. Treat whitespace-only as blank matches fields made only of whitespace and also includes empty strings when enabled. Add markers such as NULL, NA, N/A, -, or None in Custom blank markers (comma-separated). Values that do not match remain unchanged.
How to fill blank cells with a rule
Constant value writes the same replacement into each matching cell. Fill from previous row and Fill from next row copy an available non-blank value. Group value can use the first, last, or most common value in a selected group. Sequence uses a start and step, with an option to Restart per group. Formula can reference same-row columns, such as {Price} * {Qty}.
Input:
name,city,revenue
Acme,,120000
Beta,Chicago,
Gamma,Chicago,98000
Output after a constant fill:
name,city,revenue
Acme,Chicago,120000
Beta,Chicago,98000
Gamma,Chicago,98000The existing header and non-blank values remain in place. Only cells matching the selected blank settings are changed.
How to replace missing values in a CSV
First row is a header starts enabled. Turn it off for data-only input, and the columns are named Column 1, Column 2, and so on. The parser samples the first 25 lines to detect comma, tab, semicolon, or pipe delimiters. Short rows receive empty fields. Extra fields are joined into the final field.
When Fill from previous row or Fill from next row has no source, the cell stays blank and is counted as unresolved. A Formula that cannot be evaluated has the same result. Non-blank column values are classified as integer, number, date, boolean, or string.
Examples of fill rules
- Use Constant value when every matching blank in a column should receive the same text or number.
- Use Formula when a blank depends on same-row fields such as
{Price}and{Qty}. - Use Sequence when blank cells need values based on a chosen start and step.
When to use another dataset cleaning tool
Fill Blank Cells is part of Dataset Clean Tools and is for writing values into matching blanks. Use Normalize Null Values when you need to standardize markers without adding replacement data. Choose Data Cleaner for format-aware cleanup across CSV, TSV, Excel, JSON, JSONL, XML, or YAML. Use Remove Duplicate Rows from CSV, Excel, JSON & Tables when duplicate records are the issue.
Frequently asked questions
How do I fill blank cells in a CSV?
Paste the CSV into Table data or load it with browse files. Select the blank settings, check a column, and choose its fill rule. Review Preview, then use Export CSV.
How do I replace missing values in a table?
Choose a rule for each checked column. The tool writes values only into cells that match your blank definition. Existing non-blank values remain unchanged.
Can I fill empty cells from the previous row?
Choose Fill from previous row for the target column. It copies the nearest available non-blank value above, or leaves the cell unresolved when no source is available.
Can I review the filled cells before export?
Preview shows up to 200 rows with filled cells highlighted. Change log displays up to 500 entries, while its count includes all recorded changes. Use its Export CSV button to download the complete log.