Fill Empty Values in Excel Files Online
Fill empty and null values in Excel files with a custom replacement value, directly in your browser.
How to fill Empty Values in Excel files
- Drop your file onto the upload area. The tool counts the NULL values in every column and lists each column that has any, marked as numeric, text, or another type that is left as is.
- Type the replacement for text columns in Fill text nulls with. It starts empty, which fills with an empty string.
- To fill number columns too, tick Also fill numeric nulls and set the Numeric fill value. The default is 0.
- Click Fill Empty Values and check the preview.
- Click Download to save the filled file in the same format you uploaded.
Your file is processed locally in your browser and is never uploaded. The free limit is 50 MB per file; larger files work if your device has the memory for them.
Worked example
A library exports its loan records for a monthly report. Missing renewal counts mean the loan was never renewed, and missing notes should read "none" rather than appearing blank.
Input (Excel)
Excel workbook, first sheet (Sheet1)
| branch | title | renewals | notes |
|---|---|---|---|
| Central | The Overstory | 2 | damaged cover |
| Eastside | Piranesi | NULL | NULL |
| Central | Klara and the Sun | 0 | NULL |
| Northgate | NULL | 1 | reserved |
Settings
- Fill text nulls with: none
- Also fill numeric nulls: ticked
- Numeric fill value: 0
Result
| branch | title | renewals | notes |
|---|---|---|---|
| Central | The Overstory | 2 | damaged cover |
| Eastside | Piranesi | 0 | none |
| Central | Klara and the Sun | 0 | none |
| Northgate | none | 1 | reserved |
Two notes and one renewal count were NULL, and they are now "none" and 0. The missing title is also "none": the text fill value applies to every text column that has NULLs, not only notes. Values that were already present, including the real 0 renewals for Klara and the Sun, are unchanged.
Working with Excel files
Empty cells on the first sheet are read as NULL and counted. A cell that holds only a space is not empty and is not filled, so run Trim Whitespace first if a sheet was blanked by typing spaces. Formula cells that return "" are exported without a value and are treated as empty too. The count shown for each column tells you how many blank cells will change. Other sheets in the workbook are not read or filled.
Filling with 0 is a common request for Excel reports, but think about averages. AVERAGE in Excel skips blank cells and counts zeros, so filling changes the result. In the downloaded Sheet1 workbook, numeric fills are real number cells and text fills are text cells. Dates and other values are written as plain values without their original formatting. A text placeholder cannot go into a numeric column, because numeric columns only take the numeric fill value.
Frequently Asked Questions
Does filling blank Excel cells with 0 change my averages?
Yes. Excel's AVERAGE ignores blank cells but includes zeros, so filled cells pull the average down. Leave numeric nulls unfilled if the blanks mean unknown rather than zero.
Why are some Excel cells that look empty not being filled?
They probably contain a space or another invisible character, so they are not NULL. Trim the sheet first, then fill.
Are empty strings treated as missing?
No. Only NULL values are counted and filled. In CSV and Excel files, blank cells load as NULL, so they are filled. In Parquet and JSON, an empty string is a real value and is left alone.
Can I use a different fill value for each column?
No. There is one value for all text columns and one optional value for all numeric columns. Date, boolean and nested columns are not filled. For per-column values, use the SQL Query tool with COALESCE, or Coalesce Columns to fill from another column.
Are numeric columns filled by default?
No. Numeric NULLs stay NULL unless you tick Also fill numeric nulls. That is deliberate, because filling with 0 changes sums, averages and counts.
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