Convert Excel Serial Number to Date in Power Query M

Notes

Date.From treats a plain number as an Excel-style serial date automatically, using the same epoch Excel uses.

Requirements

• A number column holding Excel date serial numbers.

How to use this snippet

1. In Power BI Desktop, choose Transform data to open Power Query, then open the Advanced Editor on a query (or start from a blank query).
2. Paste the snippet and replace the placeholder names (tables, columns, file paths) with your own. Check the requirements above first.
3. Run it through the Power Query M Formatter to tidy the layout.

Related Power Query M snippets

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• Convert Unix Timestamp to DateTimeConverts a Unix epoch timestamp (seconds since 1970-01-01) into a proper DateTime value.
• Month-Year Sort Column (e.g., 2026-03)Adds a sortable text column combining year and month so month names sort chronologically instead of alphabetically.
• Week Start and Week End DatesAdds columns for the Monday (week start) and Sunday (week end) of the week each date falls in.
• Days Between Two DatesCalculates the number of whole days between two date columns.
• Relative Date Labels (Today, Yesterday, Last 7 Days)Adds a text column that labels each date relative to today, such as Today, Yesterday or Last 7 Days.

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