XLSX (Microsoft Excel Open XML Spreadsheet)

XLSX is the default spreadsheet format for Microsoft Excel since 2007. It stores tabular data, formulas, charts, pivot tables, and cell formatting in a ZIP-compressed collection of XML files. XLSX is the most widely used format for business data analysis and reporting.

MIME Type

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Type

Binary

Compression

Lossless

Advantages

+ Supports complex formulas, pivot tables, and conditional formatting
+ Smaller files than .xls due to ZIP compression
+ Open standard readable by LibreOffice, Google Sheets, and programmatic tools
+ Handles over one million rows per worksheet

Disadvantages

− Heavy files with many formulas can be slow to open and recalculate
− Complex macros require .xlsm and may not work outside Excel
− Not suitable for simple data exchange — CSV is often better

When to Use .XLSX

Use XLSX for spreadsheets that need formulas, charts, or multiple worksheets — financial models, data analysis, inventories, and reports.

Technical Details

An XLSX file is a ZIP archive with XML for worksheets, shared strings, styles, and calculation chains. Cell references, formulas, and data types are encoded in SpreadsheetML markup.

History

Microsoft introduced XLSX alongside the Office Open XML standard in 2006. It replaced the binary .xls format and was standardized as part of ECMA-376 and ISO/IEC 29500.

Convert from .XLSX

.xlsx → .arrow .xlsx → .avro .xlsx → .csv .xlsx → .docx .xlsx → .html .xlsx → .json .xlsx → .keynote .xlsx → .ndjson .xlsx → .numbers .xlsx → .ods .xlsx → .pages .xlsx → .parquet .xlsx → .pdf .xlsx → .pptx .xlsx → .tsv .xlsx → .txt .xlsx → .xls .xlsx → .xml

Convert to .XLSX

.arrow → .xlsx .avro → .xlsx .csv → .xlsx .docx → .xlsx .html → .xlsx .json → .xlsx .keynote → .xlsx .ndjson → .xlsx .numbers → .xlsx .ods → .xlsx .pages → .xlsx .parquet → .xlsx .pdf → .xlsx .pptx → .xlsx .tsv → .xlsx .txt → .xlsx .xls → .xlsx .xml → .xlsx

Related Formats

.doc .docx .epub .html .keynote .md .mobi .numbers .odp .ods

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Use Cases

B Building a Client Proposal from Mixed Document Sources B Streamlining Employee Onboarding Packet Preparation