Unit Converter
Convert between metric and imperial units instantly. Length, temperature, weight, pressure, and area conversions.
Length Conversion Tips
1 inch = 25.4 mm (exact by international definition). This makes metric-imperial length conversions precise.
Quick Reference Tables
Length Conversions
| From | To | Factor |
|---|---|---|
| 1 inch | mm | 25.4 |
| 1 foot | cm | 30.48 |
| 1 yard | m | 0.9144 |
| 1 mile | km | 1.60934 |
Temperature Conversions
| Celsius | Fahrenheit | Kelvin |
|---|---|---|
| 0°C | 32°F | 273.15 K |
| 20°C | 68°F | 293.15 K |
| 25°C | 77°F | 298.15 K |
| 100°C | 212°F | 373.15 K |
Weight Conversions
| From | To | Factor |
|---|---|---|
| 1 oz | g | 28.3495 |
| 1 lb | kg | 0.453592 |
| 1 kg | lb | 2.20462 |
| 1 stone | kg | 6.35029 |
Pressure Conversions
| From | To | Factor |
|---|---|---|
| 1 PSI | kPa | 6.89476 |
| 1 bar | PSI | 14.5038 |
| 1 atm | kPa | 101.325 |
| 1 atm | bar | 1.01325 |
Understanding Unit Conversions
Metric vs Imperial Systems
The metric system (also known as SI - International System of Units) is the most widely used measurement system in the world. It's based on powers of 10, making conversions straightforward. The imperial system is primarily used in the United States and includes units like inches, feet, pounds, and Fahrenheit.
Why Unit Conversion Matters in Engineering
In engineering and manufacturing, accurate unit conversion is critical. Electronic components and hardware often have specifications in different measurement systems:
- Datasheets: May list dimensions in millimeters (metric) or inches (imperial)
- Thread sizes: Metric (M3, M4) vs Imperial (#4-40, 1/4-20)
- Operating temperatures: Listed in °C or °F
- Pressure ratings: PSI, bar, kPa, or atm
Common Conversion Formulas
Length Conversions
inches = mm ÷ 25.4
mm = inches × 25.4
feet = meters × 3.28084
meters = feet × 0.3048Temperature Conversions
°F = (°C × 9/5) + 32
°C = (°F - 32) × 5/9
K = °C + 273.15
°C = K - 273.15Weight/Mass Conversions
kg = lb × 0.453592
lb = kg × 2.20462
g = oz × 28.3495
oz = g × 0.035274Tips for Accurate Conversions
- Use precise conversion factors: Don't round conversion factors during intermediate calculations
- Verify units: Always double-check that you're using the correct starting and ending units
- Significant figures: Match the precision of your result to your input measurements
- Temperature is different: Temperature conversions involve both multiplication and addition, unlike most other conversions
Frequently Asked Questions
How many millimeters are in an inch?
There are exactly 25.4 millimeters (mm) in one inch. This conversion factor is internationally standardized. To convert inches to millimeters, multiply by 25.4. To convert millimeters to inches, divide by 25.4.
How do I convert Celsius to Fahrenheit?
To convert Celsius to Fahrenheit, multiply the Celsius temperature by 9/5 (or 1.8) and add 32. The formula is: °F = (°C × 9/5) + 32. For example, 25°C = (25 × 1.8) + 32 = 77°F.
How many grams are in a pound?
There are approximately 453.592 grams in one pound (lb). To convert pounds to grams, multiply by 453.592. To convert grams to pounds, divide by 453.592 (or multiply by 0.00220462).
What is the difference between metric and imperial units?
Metric units (SI system) are based on powers of 10 and include millimeters, centimeters, meters, grams, and kilograms. Imperial units (used primarily in the US) include inches, feet, yards, ounces, and pounds. Metric is used globally in science and engineering, while imperial is common in the US for everyday measurements.
How do I convert PSI to bar?
To convert PSI (pounds per square inch) to bar, divide by 14.5038. The formula is: bar = PSI ÷ 14.5038. For example, 100 PSI = 100 ÷ 14.5038 ≈ 6.895 bar. To convert bar to PSI, multiply by 14.5038.
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