How to Combine Spreadsheets into One File (Excel, CSV and Google Sheets)

A spreadsheet is a table. A spreadsheet file is a container for tables. The word "spreadsheet" gets used for both, which is why combining spreadsheets can mean three different things: putting several files into one workbook, stacking several tables into one table, or turning several CSV exports into one Excel file. This guide covers all three, and it explains which one you need before you start — because picking the wrong one is the most common way to get a result that looks right and is wrong.

The files you are combining probably came from different places. One is an Excel workbook from a colleague. One is a CSV export from a survey tool. One is a Google Sheets export. One is an old .xls file from a system nobody maintains any more. That mix is normal. A good merge tool reads all of them the same way, and the result is always one clean .xlsx workbook.

What kind of "combine" do you need?

Start by looking at the files, not the tool. Ask one question: are these the same kind of table, or different kinds?

Different kinds of tables — a price list, a staff rota, a budget — belong in one workbook as separate sheets. Nothing is combined; everything is collected. Use Separate sheets mode. The result is one file you can send, with every table intact.

The same kind of table — branch reports, monthly returns, survey batches — belongs in one long table. Use Append rows mode. The tool lines the columns up by header, so it does not matter if the columns arrive in a different order, and the result is one table you can sort, filter and add up.

The same rows, different details — two lists of the same customers, one with phone numbers and one with order history — belongs in one row per ID. Use Merge by ID mode. The tool folds rows with the same ID together and keeps every distinct value.

If you are not sure, run Separate sheets first. It changes nothing, so you can look at the result and decide. Then run a second merge in the mode that fits what you saw. The files are never modified, so experimenting costs nothing but a minute.

Combining Excel, CSV and Google Sheets exports

The three formats behave differently, and the differences matter for a merge.

Excel (.xlsx). The modern format. It holds many sheets, typed values (numbers are numbers, dates are dates), and formatting. It is the best input format, because the tool can read the types directly. If a file is already .xlsx, leave it alone.

Old Excel (.xls). The format from Excel 2003 and earlier. It holds one sheet per file in practice, and fewer rows. MergeExcel reads it the same way as .xlsx, and the result is always a modern .xlsx file. If you have a folder of old .xls files, you do not need to convert them first — but do check the result, because very old files sometimes store dates as text.

CSV (.csv). A plain-text file with one row per line and commas between values. It holds one table, no formatting, and no types: every value is text until the tool reads it. CSV is the export format of almost everything — survey tools, online shops, bank statements, Google Sheets — so it is the most common input for a merge, and also the one with the most quirks. Our guide on merging CSV files covers those quirks in detail, including quoted commas and encoding.

Google Sheets. Google Sheets does not have a file of its own to upload. Export the sheet first: File, then Download, then Microsoft Excel (.xlsx) or Comma Separated Values (.csv). Export as .xlsx if the sheet has more than one tab you care about, or if the values include dates — CSV loses the date type and the tool has to guess it back. Then merge the exported file like any other.

How to combine spreadsheets step by step

Step 1: Export everything to a file. For Google Sheets, export each sheet you need as .xlsx. For a web tool, download the CSV export. Put every file in one folder. If a file is a PDF, it is not a spreadsheet — convert it first, or find the export that produces a spreadsheet.

Step 2: Open each file and check the header row. The first row should name every column. Fix two things now: headers that mean the same thing but are spelled differently, and blank header cells. A blank header becomes "Column 3" in the merged table, which is honest but not useful — give it a real name.

Step 3: Upload to MergeExcel. Drag the files onto the upload area. The tool shows the name and size of each file. Check that the right files arrived, and remove any that do not belong. The free plan merges up to 10 files at a time; if you have more, split them into batches and merge the batches, as explained in our guide to merging multiple files at once.

Step 4: Pick the mode. Separate sheets, Append rows, or Merge by ID — whichever matches what you decided at the start. For Append rows, consider the "Source File" column: it records which file each row came from, which is invaluable when a row looks wrong later. For Merge by ID, type the exact header name of the ID column.

Step 5: Read the audit report. Before you download, read the summary: rows in, rows out, duplicates removed, rows folded by ID, rows skipped. The arithmetic should balance. Then read the audit notes for header mismatches and empty sheets. A mismatch is information, not an error — decide whether it is expected or a spelling mistake.

Step 6: Download and verify. Open the merged workbook and check the row count, the first and last rows, three rows you know well, and the sum of one numeric column against the source files. Save your copy; the online copy is deleted after 72 hours.

Why combining spreadsheets is harder than it looks

Three problems make this job harder than "just put the files together," and all three come from the files, not the tool.

Different column orders. One file puts "Total" in column B, another puts it in column D. A person pasting by hand lines columns up by eye and gets it wrong sooner or later. A merge tool lines them up by header text, so order does not matter. This is the single biggest reason to use a tool instead of copy-and-paste.

Different header spellings. "Customer ID", "Cust ID", "CustomerID" — three spellings, one column. A tool treats them as three columns unless you fix the spelling first. The audit report lists the mismatch, so you can see it and fix it. Public datasets avoid this by publishing a data dictionary with every file: the National Center for Education Statistics documents the exact column names in its data files, and every file in a release uses the same names. Copy that habit for your own files.

Different types for the same column. One file stores amounts as numbers, another stores them as text. The merged column contains both, and a sum ignores the text. The total looks plausible and is wrong. Convert text to numbers in the source files before you merge, and check the sum afterwards.

Combining spreadsheets from different systems

Files from different systems are the hardest case, because each system has its own idea of a good export. A survey tool exports one row per response, with a column for every question. A shop exports one row per order, with a column for every product field. A bank exports one row per transaction. These are all tables, but they are not the same table, and they should not be stacked into one.

When the files come from different systems, ask whether they share an ID. If they do — a customer ID in the survey and the same customer ID in the shop export — Merge by ID can combine them into one row per customer, keeping every distinct value from both files. That is the most powerful use of the tool, and also the one that needs the most care: the ID must mean the same thing in both files. A customer ID that is unique in one system and reused in another will fold two different people into one row. Check the ID column first: it should be unique within each file, and it should have no blanks.

If the files do not share an ID and are not the same kind of table, use Separate sheets. One workbook, one sheet per file, nothing combined. That is still combining spreadsheets — into one file — and it is the right answer for files that should not be stacked.

Checking a combined spreadsheet

A combined file is only done when it has been checked. The checks are the same whatever the mode, and they take about five minutes.

1. Row count. The merged row count should equal the source rows minus duplicates, minus rows folded by ID, minus rows skipped. The report shows all four numbers.
2. Known rows. Find three rows you know — a big order, an unusual name, the first row of each file — and check every value.
3. Edges. Look at the first five and last five rows. Errors cluster at the edges.
4. One sum. Add up a numeric column and compare it with the source files. If the totals differ, a column was misaligned or a value is stored as text.
5. Blanks. Filter on a column that should never be blank, like the ID. Blank rows came from a file that lacked that column.

If you are combining files for someone else — a manager, a client, an auditor — keep the audit report with the merged file. On Starter and Pro plans it downloads as a CSV. It is the record of what was merged and what was left out, and it answers the question "where did this number come from?" without a meeting. The U.S. Census Bureau publishes change notes with its data releases for the same reason: a number without a record is a number nobody can defend.

Frequently asked questions

How do I combine spreadsheets into one file? Upload the files to an online merge tool, pick Separate sheets for one workbook with many sheets, or Append rows for one long table, and download the result. No account is needed to try, and the files are never modified.

Can I combine a CSV file with an Excel file? Yes. The tool reads .xlsx, .xls and .csv files in the same merge, and the result is always a .xlsx workbook. See our guide on merging CSV files for the details.

Can I combine Google Sheets? Export each sheet from Google Sheets as .xlsx or .csv first (File, then Download), then merge the exported files. Export as .xlsx when the sheet has dates or more than one tab.

Will combining spreadsheets keep my formatting? Values are combined; cell formatting is not carried over. The result is a clean data table. Add formatting to the merged file afterwards — it is faster to format one table than many.

What if the spreadsheets have different columns? Append rows uses the union of all headers. A column that exists in only some files stays blank for the other files' rows, and the audit report lists every missing column per file.

Is it free to combine spreadsheets online? The free plan merges up to 10 files at a time, 10 times a month. Starter ($9 a month) merges 50 files per run and adds Merge by ID, deduplication and the downloadable audit report. Pro ($19 a month) is unlimited with 200 files per run. The full comparison is on the pricing page.

References

• National Center for Education Statistics, data files and documentation: https://nces.ed.gov/
• U.S. Census Bureau, data documentation: https://www.census.gov/
• U.S. Bureau of Labor Statistics, published datasets: https://www.bls.gov/
• Microsoft Support, Excel help and how-to articles: https://support.microsoft.com/