5 min readUpdated for 2026NIST SP 811 Standards

Weight Conversion Formula Guide: Master Mathematical Formulas for All Units

The ultimate cheat sheet for every weight conversion equation across metric, imperial, US customary, and SI units.

⚡Key Takeaways & Quick Summary

  • Master formula list covering kg, lbs, g, oz, st, tonnes, short tons, and long tons
  • Exact multipliers standardized by the International System of Units (SI)
  • Scientific notation guide for micro and macro weight scales

Master Conversion Table of Factors (Relative to 1 Kilogram)

Every mass measurement can be converted precisely through the SI kilogram base standard:

  • 1 Kilogram (kg) = 1.0 kg (Base SI)
  • 1 Gram (g) = 0.001 kg
  • 1 Milligram (mg) = 0.000001 kg
  • 1 Pound (lb) = 0.45359237 kg
  • 1 Ounce (oz) = 0.028349523125 kg
  • 1 Stone (st) = 6.35029318 kg
  • 1 Metric Ton (t) = 1,000 kg
  • 1 US Short Ton = 907.18474 kg
  • 1 Imperial Long Ton = 1,016.0469088 kg

Measurement Standards & Accuracy

Standard Multipliers

Factors based on the 1959 International Yard and Pound Agreement and NIST SP 811.

Sources
  • BIPM International System of Units
  • NIST SP 811 Guide
  • ISO 80000-4
Accuracy & Policy
Standard Exact Multipliers (e.g., 1 lb = 0.45359237 kg)
Reviewed: October 2026 • About our methodology →

Official Government & Scientific Citations

Sources

Verified measurement documentation from NIST, BIPM, and ISO: