ConvertCSV

Browser-based CSV transform

Group CSV By Column

Collapse rows into one row per group with a count and an optional sum. Everything runs locally in your browser — paste CSV, set options, preview, then copy or download.

Input

Paste CSV or upload a file

Options

Configure how this transform runs

Output Preview

Transformed CSV

Run the transform to preview CSV output here.

Group CSV By Column

Grouping collapses a flat export into one row per distinct value of a column. Choose the column to group by and the output lists each value once, with the number of rows that carry it. Add a sum column and every group also gets the total of a numeric field. It is the same summary people usually build with a pivot table or a SUMIF formula, produced as plain CSV.

Paste the rows or upload a file, enter the group column and, if wanted, the column to total, then copy or download the summary. The computation happens in your own tab.

Key features

  • One output row per distinct value in the group column
  • Row count for every group
  • Optional numeric sum for one chosen column

About the CSV to grouped CSV format

The output header is the group column, then row_count, then, when a sum column is set, that column's name followed by _sum. Groups appear in the order they first show up in the input rather than alphabetically. Sort the result afterwards if you want a ranking.

Sums parse each cell as a plain decimal number. Empty sum cells add nothing to the total, but their rows still count toward row_count. A group whose sum cells are all empty reports 0.

How it works

The tool scans the rows once and keeps a running count and sum for every group key in a lookup table. When the scan ends, it writes one row per key.

Common use cases

  • Counting orders per country to decide which market to review first.
  • Totalling spend per customer from a line-item export.
  • Checking how many records each import batch contributed to a shared table.
  • Getting per-category counts from a log file before building a chart.

How to use this tool

  1. Paste the export, or upload the file, that you want to summarise.
  2. Enter the header name of the column to group by.
  3. Type a numeric header in the sum box to total it, or leave the box empty for counts only.
  4. Check the row_count and total values in the preview, then copy or download the summary.

Example

Input (five order rows)

order_id,customer,country,total
1001,Ana,Portugal,40.50
1002,Ben,Canada,12.00
1003,Ana,Portugal,19.25
1004,Chloe,France,88.00
1005,Ben,Canada,5.75

Output (group by customer, sum total)

customer,row_count,total_sum
Ana,2,59.75
Ben,2,17.75
Chloe,1,88

Tips for best results

  • Run once without a sum column to see the group sizes, then add the sum once the grouping looks right.
  • Matching is exact apart from surrounding spaces, which are trimmed. Ana and ana are two groups, so normalize capitalization in your source first.
  • Pipe the summary into Sort CSV on row_count, descending, to list the busiest groups at the top.

Common errors and how to fix them

Column "total" has a non-numeric value "$40.50" in data row 1.
Remove the currency symbol and separators from the sum column, or clear the sum column setting for a count-only summary.
The group-by column name is blank.
The group field was left blank. Type the header name exactly as it appears in the first line; header matching ignores letter case.
Output column names collide.
The group column already has the name row_count, or it matches the generated sum header. Rename that column in the source file, then run the summary again.

Frequently asked questions

Can I group by two columns at once?

Not in one run. Build a combined key column first, for example country and city joined with a spreadsheet formula, then group by that new column.

Does the sum column accept decimals or negatives?

Yes. Totals are written with toPrecision(12), so 88.00 is shown as 88 and 0.1 + 0.2 as 0.3.

For more background on data formats and conversion workflows, read our format guides.