Excel Price History to CSV for Backtesting

Price histories are often kept in Excel, but a backtest or script reads CSV. A careless save can change dates and decimals.

Open the Excel to CSV converter

Open the Excel to CSV converter and drop the workbook. Only the first sheet of an .xlsx file is read, and old .xls files must be saved as .xlsx first. Put the price table on the first sheet, with one header row and no merged cells or totals row.

Check the result, not just the file. Dates should keep one format, ideally ISO. Prices should keep their decimals, and symbols should stay text. A date that Excel stored as text and one stored as a date number can sit in the same column, so sort by the date column and look at the first and last rows.

Run the Data Profiler to count blanks and duplicate dates, and compare the row count with the sheet. Remember Excel holds up to 1,048,576 rows, so a longer history was already cut before it reached you.

Everything runs in your browser and nothing is uploaded.

Open the Excel to CSV converter

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How to use the Excel to CSV converter: step by step

  1. Put the price table on the first sheet.
  2. Open the Excel to CSV converter and drop the workbook.
  3. Check the first and last rows and the date format.
  4. Download CSV and profile it for blanks and duplicates.

When to use the Excel to CSV converter

  • Feed an Excel price history to a script
  • Prepare data for a backtest
  • Hand a clean file to a developer
  • Check dates and decimals before loading

Example

Input: A Excel file with the columns id, name and age.

Output: id,name,age 1,Ada,36 2,Alan,41

Frequently asked questions

How do I convert Excel to CSV?

Drop your Excel file (or paste the data), check the options, click Convert and download the CSV result.

How big can a file be?

It depends on your device. A few hundred MB usually works.

Which conversions does the Format Converter support?

Any direction between JSON, CSV, Parquet and Excel (.xlsx), for one file or a whole folder. Nested JSON is flattened into columns such as address.city. For Excel, the first sheet is read; old .xls files are not supported.

Why did my number or date change after converting?

Types are detected from the values. Turn off "Detect types" to keep everything as text, which also keeps leading zeros in IDs and phone numbers.

Tip: Sort by date and check the first and last rows. Mixed text and number dates show up there.