How-To
Beginner
1 min read
253 words
Unit Conversion Fundamentals: A Complete Reference
Converting between units is essential in science, engineering, cooking, and everyday life. This guide covers dimensional analysis, common conversion factors, and techniques to avoid errors.
Key Takeaways
- Dimensional analysis uses conversion factors as fractions where the numerator and denominator are equivalent quantities.
- Temperature conversions use formulas, not simple factors:
- When no direct factor exists, chain multiple conversions.
- Forgetting to square or cube conversion factors for area and volume
The Dimensional Analysis Method
Dimensional analysis uses conversion factors as fractions where the numerator and denominator are equivalent quantities. Multiply your value by the factor so that unwanted units cancel out.
Example: Convert 5 miles to kilometers.
5 mi * (1.60934 km / 1 mi) = 8.047 km
The mi units cancel, leaving km.
Common Conversion Factors
Length
| From | To | Factor |
|---|---|---|
| inches | centimeters | × 2.54 |
| feet | meters | × 0.3048 |
| miles | kilometers | × 1.60934 |
| nautical miles | kilometers | × 1.852 |
Weight / Mass
| From | To | Factor |
|---|---|---|
| ounces | grams | × 28.3495 |
| pounds | kilograms | × 0.453592 |
| tons (US) | metric tonnes | × 0.907185 |
Temperature
Temperature conversions use formulas, not simple factors:
- Celsius to Fahrenheit:
F = C * 9/5 + 32 - Fahrenheit to Celsius:
C = (F - 32) * 5/9 - Celsius to Kelvin:
K = C + 273.15
Chaining Conversions
When no direct factor exists, chain multiple conversions. To convert square feet to square meters: convert feet to meters first (× 0.3048), then square the result: 1 ft² = 0.3048² m² = 0.0929 m².
Common Mistakes
- Forgetting to square or cube conversion factors for area and volume
- Mixing up US gallons (3.785L) and Imperial gallons (4.546L)
- Using troy ounces (31.103g) when standard ounces (28.35g) are needed