How to Convert Between Measurement Units
Unit conversion is needed constantly in science, engineering, cooking, and daily life. Learn conversion factors for length, weight, temperature, and more.
Key Takeaways
- Most of the world uses the metric system (SI units), while the US primarily uses imperial/customary units.
- Temperature is the trickiest conversion because it involves both scaling and offset.
- Chain conversions by multiplying by conversion factors as fractions.
- Conversions introduce rounding errors.
- ## Essential Conversion Factors | Conversion | Factor | |-----------|--------| | inches → cm | × 2.
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Metric vs Imperial
Most of the world uses the metric system (SI units), while the US primarily uses imperial/customary units. Converting between them requires memorizing a few key factors or using conversion tools.
Essential Conversion Factors
| Conversion | Factor |
|---|---|
| inches → cm | × 2.54 |
| miles → km | × 1.609 |
| pounds → kg | × 0.4536 |
| gallons → liters | × 3.785 |
| °F → °C | (°F - 32) × 5/9 |
Temperature Conversion
Temperature is the trickiest conversion because it involves both scaling and offset. Celsius to Fahrenheit: multiply by 9/5 then add 32. Kelvin is Celsius + 273.15 (no scaling needed).
Dimensional Analysis
Chain conversions by multiplying by conversion factors as fractions. To convert miles per hour to meters per second: mph × 1609m/mi × 1hr/3600s. Units cancel mathematically, leaving the desired unit.
Precision and Rounding
Conversions introduce rounding errors. Keep at least 2 more significant figures than needed during calculation, then round only the final result.
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