Are spreadsheet add-ins trustworthy?

Pin versions and document assumptions; add-ins update silently and can change rounding.

Should I use CONVERT() in Excel?

It helps for built-in pairs, but document the Excel version—behavior differs across locales and versions.

Spreadsheet conversion QA

Spreadsheets hide unit mistakes inside formulas. Use separate columns for raw values, unit labels, and converted outputs; never embed unexplained constants like 1.8 or 25.4 inside nested IFs without comments.

Treat formula changes to conversion factors like code changes: diff review and pinned add-in versions.

Key takeaways

Columns: raw value, unit enum, SI storage, display.
Round only in presentation cells.
Dropdown unit lists prevent `kg` vs `kgs` typos.
Linked ranges > pasted values for regulated metrics.

How to convert

From

Result

From

Result

1 m = 3.28084 ft

Column contract

Name columns `value_si`, `unit`, `value_display` so conversions are traceable in audits.

Avoid mixing inputs in one cell

Do not type “12 kg (26 lb)” in one cell—parsers and pivot tables break.

Data validation lists for units

Dropdowns for allowed units prevent typos like `kgs` vs `kg`.

Round at the edge

Keep full precision internally; round only in presentation cells to avoid compounded rounding error.

Review diffs in shared sheets

Highlight formula changes that alter conversion factors—treat them like code review.

LAMBDA and LET for clarity

Name intermediate conversion factors once per sheet—`LET(ft_to_m, 0.3048, …)` beats inline magic numbers.

CSV export encoding

Decimal separators differ by locale; export UTF-8 with explicit units in headers to avoid Excel mis-parsing.

IMPORTRANGE vs manual paste

Linked ranges preserve formula lineage; pasted values hide unit drift—prefer links for regulated metrics.