Add Calculated Column to Excel Files Online
Add a new column to Excel files computed from an arithmetic expression over existing columns. No formulas, no code — just point and click.
How to add Calculated Column to Excel files
- Drop your file onto the upload area. It is loaded into the in-browser engine and the first 200 rows are shown.
- Type a name for the new column. The default is "calculated".
- Build the expression. Pick a column or "constant" on the left, choose an operator (+, −, ×, ÷ or %), then pick a column or constant on the right. The two sides start on the first and second columns of the file.
- Click Calculate. The new column is added as the last column and the preview updates.
- Download the result 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 hardware shop exports its stock count and wants the value of stock on the shelf for each product line: units counted multiplied by unit cost. One line was not counted this week.
Input (Excel)
Excel workbook, first sheet (Sheet1)
| sku | item | units | unit_cost |
|---|---|---|---|
| HW-101 | Wood screws 4x40 (box) | 38 | 4.25 |
| HW-102 | Brass hinge pair | 12 | 7.5 |
| HW-103 | Wall plugs (100) | 0 | 2.75 |
| HW-104 | Masking tape 24mm | NULL | 3.25 |
| HW-105 | Sandpaper P120 (10) | 25 | 5.75 |
Settings
- New column name: stock_value
- Expression: units × unit_cost
Result
| sku | item | units | unit_cost | stock_value |
|---|---|---|---|---|
| HW-101 | Wood screws 4x40 (box) | 38 | 4.25 | 161.5 |
| HW-102 | Brass hinge pair | 12 | 7.5 | 90 |
| HW-103 | Wall plugs (100) | 0 | 2.75 | 0 |
| HW-104 | Masking tape 24mm | NULL | 3.25 | NULL |
| HW-105 | Sandpaper P120 (10) | 25 | 5.75 | 143.75 |
Each row multiplies its own units by its own unit_cost, and the result is appended as stock_value. Wall plugs have a real count of 0, so their value is 0. Masking tape has no count at all, so its value is NULL, not 0: any arithmetic with a NULL operand gives NULL. Run Fill Empty Values first if a blank count should be treated as zero.
Working with Excel files
The tool reads the first sheet only. Each cell is read as the text Excel would display, then types are inferred from that text. This matters for arithmetic. A plain number in General format loads as a number. A cell formatted as currency or with a thousands separator, such as "$1,200.00" or "1,234.50", loads as text, and the calculation fails. Set those columns to General or plain Number format in Excel before uploading, or clean them with Find & Replace here.
Cells that hold formulas contribute their last calculated value, not the formula, so the output is a static number. The downloaded workbook has one sheet, Sheet1, with values only. Excel formulas, number formats and column widths from the original are not carried over. If you need the calculation to stay live in Excel, write the formula there. Use this tool when you want a fixed result column or the file is too large to open comfortably.
Frequently Asked Questions
Will the downloaded Excel file contain a formula for the new column?
No. The new column contains plain values computed in the browser. There is no formula behind them, so they will not update if you later edit the source cells in Excel.
Why is my Excel price column not accepted in the expression?
It was probably formatted as currency or with thousands separators, so its displayed text such as "$1,200.00" was read as text. Change the cell format to General in Excel, or remove the symbols with Find & Replace, then try again.
Can I use more than two operands or brackets in one expression?
No. Each run applies one operator to two operands, which can be columns or constants. Every run starts from the file you uploaded, so to chain steps, download the result, drop it back in and calculate again. For longer formulas, use the SQL Query tool.
What happens if I divide by zero?
The calculation does not stop. Rows where the divisor is zero get an empty (NULL) result, for both ÷ and %, whatever the column types. Every format writes it the same way, as an empty value.
How does the % operator work?
It is modulo, the remainder after division, not percent. 17 % 5 gives 2, and the sign follows the left operand, so -5 % 3 gives -2. To get a percentage, divide one column by another, then multiply the result by the constant 100 in a second run.
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