Birdie XLSX to XLS Converter: Fast & Reliable File Conversion

Best Settings for Accurate Output

1. File compatibility

• Input check: Ensure source files are valid XLSX (open in Excel/LibreOffice once to confirm no corruption).
• Target format: Choose XLS (BIFF8 / Excel 97–2003) if you need widest legacy compatibility; use BIFF8 to preserve more features than older BIFF versions.

2. Workbook and sheet options

• Preserve workbook structure: Enable the setting that keeps sheet order and hidden sheets.
• Sheet selection: If converting partially, select only necessary sheets to avoid exceeding XLS row/column limits.

3. Cell limits & layout

• Truncate/Map cells: Turn on automatic handling for XLS limits — XLS supports 65,536 rows × 256 columns. Set the converter to:
  • Split large sheets into multiple sheets or files, or
  • Truncate with warning (if you prefer a single-sheet output).
• Wrap/merge handling: Preserve merged cells where possible; set a fallback to unmerge and replicate values if preservation fails.

4. Data types & formulas

• Formula preservation: Enable formula conversion; where formulas use functions unavailable in XLS, enable an option to convert formulas to values.
• Date/time mapping: Use explicit date system mapping (1900 vs 1904) to avoid 1–2 day offsets.
• Number formats: Preserve custom number formats; set a fallback to closest built-in format.

5. Formatting & styles

• Cell styles: Preserve fonts, fills, borders, and alignment. If XLS style limits are exceeded, enable style consolidation (merge similar styles).
• Conditional formatting: If full conversion isn’t supported, convert conditional formatting results to static values or recreate simpler rules.

6. Embedded objects & external links

• Embedded content: Extract and attach embedded files (images, charts) where possible; otherwise choose to embed as images.
• External links: Convert or remove external data connections; prefer converting linked data to values to prevent broken links.

7. Images & charts

• Images: Set image quality (e.g., 96–150 DPI) to balance file size and clarity. Use PNG for lossless content, JPEG for photos.
• Charts: Prefer converting charts to native XLS chart objects; if unsupported, export as images and place them on sheets.

8. Encoding & localization

• Text encoding: Use UTF-8/Unicode to preserve non‑ASCII characters.
• Locale settings: Match source locale for decimal separators, thousands separators, and list separators to avoid parsing errors.

9. Batch conversion settings

• Concurrency: Limit parallel jobs to avoid memory spikes; test and adjust based on available RAM/CPU.
• Error handling: Set retry logic, logging verbosity, and an option to skip problematic files while reporting issues.

10. Verification & testing

• Checksum/size compare: Use file checksums and spot-checks on converted files.
• Automated validation: Run key tests: row/column counts, sample formulas, date sanity, and visual inspection of critical sheets.
• Backup originals: Always keep originals until verification completes.

Quick recommended profile (balanced)

• Target format: BIFF8 (XLS)
• Preserve workbook structure: ON
• Large-sheet handling: Split into multiple sheets/files (preferred)
• Formula handling: Preserve where possible; fallback to values for unsupported functions
• Images: PNG @ 150 DPI
• Encoding: UTF-8/Unicode
• Error handling: Log + skip problematic files

If you want, I can turn this into a one‑page checklist or provide exact setting names for a specific version of Birdie if you tell me which one you have.