Combine CSV Files with Matching Columns

Combine CSV files by matching their column names, even when the columns appear in different orders. CombineSheets can also combine UTF-8 CSV with XLSX, XLS, XLSM, and ODS inputs. Choose one table for CSV output, check the mapping report, and download the combined values without uploading your files.

Try sales-february.csv alongside sales-january.xlsx. They contain the same core order fields, but February changes their order and adds Sales Rep. This makes a small, inspectable example of a mixed-format run.

Combine CSV files by header name

The first non-empty row is treated as the header. Matching ignores capitalization and spaces at the beginning or end of a name. It does not match by position, so a Revenue column can move without being placed under Units in the result.

Prepare each input so that its actual column labels are the first non-empty row. A report title above the labels can interfere with that assumption. Blank or duplicate header names stop the merge and need correcting in the source.

The first table sets the output column order. New names in later inputs are appended to the end, while missing columns produce empty cells. Matching names does not standardize their meaning. If one file calls a field Revenue and another calls it Sales, decide whether they represent the same thing and edit the headers before combining.

Check the report's new and missing columns for every input. An unexpected extra column may be a spelling difference rather than a genuinely new field. For workbook-specific selection advice, see how to combine Excel sheets.

Mix CSV reports and workbook sheets

Select January and February, use One table, and review the columns. January has Order ID, Date, Region, Product, Units, and Revenue. February has Region, Order ID, Date, Product, Revenue, Units, and Sales Rep.

With January first, Sales Rep appears after Revenue in the combined result. January records have empty cells in that column. The two samples contain 12 data rows altogether. One February row repeats a January order exactly, including an empty Sales Rep value after alignment.

Enable duplicate removal to keep the first copy and produce 11 data rows. Comparison uses the whole business row, ignoring the optional source column. An order with a changed amount is not an exact duplicate, even if its Order ID matches.

Add Source file when you need a way to trace an output row. For workbooks with multiple sheets, that field includes the workbook and worksheet names. If Source file already exists in your data, the added field is named Source file (2).

Export Excel sheets as one CSV table

Choose the worksheets to include and append their records with One table. A CSV output contains one table only. If you want selected worksheets to remain separate inside one file, choose Separate sheets and export XLSX instead.

CSV output contains values, not live formulas. A formula contributes its last saved value. When no saved value exists, the tool stops and asks you to recalculate and save in your spreadsheet app. Recalculate before merging if totals depend on recent changes.

Formatting, column widths, merged-cell layout, conditional formatting, data validation, comments, charts, images, pivot objects, macros, and external links are not preserved. A CSV is suitable for moving records between systems; keep the workbook for its original structure and appearance.

Encoding and leading-zero checks

Use UTF-8 CSV input. Exported CSV can include an optional UTF-8 byte order mark, or BOM, which helps some spreadsheet apps recognize the encoding. Choose it according to the app that will read your output, then open a small result to check the text.

Leading zeros in text IDs are kept. A value such as 000101 should still be treated as an identifier, not an amount. When importing the downloaded CSV into a spreadsheet app such as Excel, explicitly import that column as text. Opening a CSV directly may let the receiving app reinterpret it as a number.

Empty cells remain different from zero. Include both cases in your checks if the next system treats a blank as unknown and zero as a measured quantity.

Can I use a different input extension?

Supported inputs are XLSX, XLS, XLSM, ODS, and UTF-8 CSV. Detection examines the contents, not just the extension. Renaming an unsupported file does not convert it. Password-protected and encrypted files are rejected.

How many files can I combine?

Free batches allow 50 MB total and 30 files, with 1,000,000 non-empty cells for merge and split. A pass raises those to 100 MB, 300 files, and 2,000,000 cells. Phone limits are 20 MB and 300,000 cells for every tier. Browser memory can still limit a run.

What should I check after downloading?

Verify the header order, output row count, a text ID, a blank, and a zero. Compare the duplicate count with your expectations. Use the monthly report guide for a fuller before-and-after review.