The working matters.
Independent calculation modules
Each calculator uses a registered input schema and an independent calculation branch. Tests cover known examples and important edge cases, including zero interest, invalid denominators, leap days, and unit conversions.
Precision and display
Calculations use JavaScript double-precision numbers. Financial displays use USD with two decimal places, rounded to the nearest cent. Other numeric displays use up to four decimal places, while underlying calculations retain greater precision. This is an estimate engine, not a banking ledger.
Dates and units
Date-only tools use UTC calendar arithmetic so daylight-saving changes do not alter elapsed days. Unit converters use international definitions. US customary units are available alongside metric measurements.
Sources and review
Health equations cite primary research or CDC guidance. Statistical explanations reference NIST. Elementary formulas are stated directly on their tool pages. Formula review date: October 23, 2026.
Editorial automation
The optional generation pipeline retrieves approved reference material, drafts original text, checks example values against calculator code, and requests a second model review. These automated checks do not equal expert fact-checking. High-risk or insufficient-quality output stays unpublished. The API and unattended schedule require configuration.