XLSX Format Guide & Converter

Office Open XML Spreadsheet is a Microsoft Excel Open XML workbook for spreadsheets, formulas, and charts, introduced by Microsoft (2007). XLSX is the business default for spreadsheets: multiple sheets, formulas, pivot-friendly data, and formatting. Use CSV when you only need raw values for import, and PDF when you need a non-editable snapshot of a report.

Full name

Office Open XML Spreadsheet

Kind

spreadsheet

File extension

.xlsx

MIME type

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

Developer / standard

Microsoft · 2007

Compression

none or container

Quality model

Lossless / not lossy

Container

No / single bitstream typical

Common codecs

—

Technical sources

—

Transparency

Not supported

Animation

No (still / non-animated typical use)

Typical size

Small to large depending on data and embedded images

Browser support

Edit via Sheets/Excel online; not a native browser grid format

Compatibility

Opens in Excel, Google Sheets, LibreOffice Calc, and Numbers with occasional formula quirks — the spreadsheet exchange default

XLSX compression: none or container. Lossless (or non-destructive packaging) keeps reconstructable data — size savings come from packing efficiency, not throwing detail away. Typical size profile: Small to large depending on data and embedded images. Quality note: Full spreadsheet fidelity in Excel-compatible apps

Quality: Full spreadsheet fidelity in Excel-compatible apps

Typical size: Small to large depending on data and embedded images

XLSX does not support an alpha channel. Convert to PNG, WebP, AVIF, or SVG when you need transparent backgrounds.

XLSX is a still-media or non-animated format in typical use. Use GIF, APNG, video, or animated WebP when you need motion.

Workbook properties and sometimes defined names/comments; not a substitute for proper data lineage docs.

• Financial models
• Operational trackers
• Formatted reports
• Data analysis in Excel/Sheets
• Sharing workbooks with businesses

• Huge raw dumps better left as CSV/database tables
• Final legal records that must not change (use PDF)
• Simple lists that do not need formulas
• Binary storage of unrelated documents

• Industry spreadsheet standard
• Formulas and multiple sheets
• Formatting and charts
• Huge add-in ecosystem
• Familiar to finance and ops teams

• Formula compatibility quirks across apps
• Easy to corrupt with bad generators
• Macros can be risky
• Unwieldy for massive data

Opens in Excel, Google Sheets, LibreOffice Calc, and Numbers with occasional formula quirks — the spreadsheet exchange default

Browsers: Edit via Sheets/Excel online; not a native browser grid format

• Microsoft Excel
• Google Sheets
• LibreOffice Calc
• Format Convertly

• Desktops and office mobile apps
• Modern desktops
• Phones and tablets with compatible apps

Open in Excel or upload to Google Sheets. For stubborn imports, save a CSV values copy as a fallback.

Convert XLSX to CSV for database imports or to PDF for read-only reports using Format Convertly’s private in-browser tools.

• Pick a target format from popular conversions or the full list below.
• Your file is read into browser memory — not uploaded to a server.
• Download the result when conversion finishes.

Incoming conversions strengthen the XLSX cluster — e.g. JPG → XLSX, PNG → XLSX.

Compare XLSX with related formats to pick the right container for quality, size, and compatibility.

Decision pages that cite XLSX — the next hop after a vs comparison.

Tools extend the format graph beyond one-off conversion — compression, metadata, and utilities for real workflows.

Uploading sensitive XLSX files to a random converter creates a third-party copy you cannot control. Format Convertly keeps processing on-device so photos, contracts, and exports stay private.