Reference Libraries
Curated reference tables for measurement, time, finance, and more — designed to give you quick access to the data you need without digging through a textbook.
Measurement Reference Library
Metric prefixes, paper sizes, wire gauge, drill bit sizes, thread sizes, and common unit reference tables.
- Metric Prefixes
- Paper Sizes
- Wire Gauge
- Drill Bit Sizes
- Thread Sizes
Date & Time Reference Library
Federal holidays, week number lookup, day of year, calendar reference, and time zone reference.
- Federal Holidays
- Week Numbers
- Day of Year
- Calendar Reference
- Time Zone Reference
Finance Reference Library
Retirement contribution limits, IRA limits, HSA limits, tax brackets, and US inflation history.
- Retirement Limits
- IRA Limits
- HSA Limits
- Tax Brackets
- Inflation History
Printable Resources
Print-ready conversion charts, metric reference, kitchen conversions, and time references.
- Conversion Charts
- Metric Chart
- Kitchen Conversions
- Time References
Authoritative Sources
The content and formulas on Apex Conversion are validated against the following authoritative references. For methodology details, see our Methodology page.
Conversion Standards
- NIST — National Institute of Standards and Technology
U.S. metric and SI unit definitions
- BIPM SI Brochure
International System of Units (SI) official publication
- NIST Special Publication 811
Guide for the Use of the International System of Units
Financial Sources
- U.S. Federal Reserve
U.S. monetary policy and financial data
- European Central Bank (ECB)
Euro area monetary policy and exchange rates
- Internal Revenue Service (IRS)
U.S. tax brackets, contribution limits, and tax rules
- U.S. Bureau of Labor Statistics
CPI data and inflation history
Health Sources
- Centers for Disease Control and Prevention (CDC)
BMI standards, body measurement guidelines
- National Institutes of Health (NIH)
Health measurement standards and caloric guidelines
- World Health Organization (WHO)
International health and body mass index standards
- USDA — Dietary Guidelines
Nutrition data, cooking measurements, food safety
Time Standards
- NIST Time Services
Official U.S. time standard
- IANA Time Zone Database
Authoritative global time zone definitions
- BIPM — International Time Bureau
Coordinated Universal Time (UTC) standards
Measurement Standards
- ASTM International
Sizing standards for clothing, footwear, and rings
- ISO — International Organization for Standardization
Global measurement and sizing standards
- NIST Weights and Measures
U.S. weights, measures, and unit standards
- U.S. Government Publishing Office — CFR
Regulatory definitions for U.S. measurement units