When is this useful?
Use it for row-by-row arithmetic such as qty × price, selling price minus cost, or two measurements that need a derived column. The original A and B values stay in place; the new result is appended as another column.
Free web tool
Calculate two numeric CSV columns and append the result as a new column.
Need a new amount column from quantity × price, or a difference column from two numeric fields? This tool calculates two CSV columns and appends the result without overwriting the originals. Blank cells are not silently treated as zero.
Use it for row-by-row arithmetic such as qty × price, selling price minus cost, or two measurements that need a derived column. The original A and B values stay in place; the new result is appended as another column.
This is the easy place to lose information. If either input is blank or cannot be read as a finite number, the result stays blank and the row is counted as uncalculated. That keeps “missing” separate from “actually zero.”
Formatted strings such as 1,200 or values with units such as 10kg do not parse as plain numbers here. Normalize those fields before doing the calculation.
For A ÷ B and (A-B)/B × 100, a zero B would make the calculation undefined. The tool leaves that result blank instead of writing Infinity or an error token into your CSV.
The percentage operation treats B as the baseline. Swap A and B and the meaning changes, so it is worth checking which column is your reference value.
Rows are not aggregated and the source columns are not rewritten. With qty=2 and price=1200, multiplication simply appends 2400 to that row. That makes it easy to compare the derived value with its inputs later.
If 1,000 rows produce “998 calculated / 2 uncalculated,” inspect those two before you download. A blank, a text value, or a zero denominator can be more useful to know about than the 998 successful calculations.