Unit Converter
Convert between length, weight, and temperature units instantly.
Result
39.370079 in
100 cm = 39.370079 in
Understanding Unit Conversions
Unit conversion is a fundamental skill used across science, engineering, cooking, travel, and daily life. Our unit converter supports three major categories: length, weight, and temperature. It handles conversions between metric (SI) and imperial systems, making it invaluable for international communication and commerce.
The metric system, used by the vast majority of countries worldwide, is based on powers of 10, making conversions within the system straightforward. The imperial system, primarily used in the United States, uses less intuitive relationships between units (12 inches in a foot, 3 feet in a yard, 5,280 feet in a mile). Converting between these systems requires specific conversion factors.
Temperature conversion is unique because the scales do not share a common zero point. The Celsius scale sets 0 at the freezing point of water and 100 at the boiling point. Fahrenheit sets 32 at freezing and 212 at boiling. Kelvin starts at absolute zero (-273.15 C), which is the lowest possible temperature. The formulas are: F = C x 9/5 + 32 and K = C + 273.15.
Accurate unit conversion is critical in fields like science, medicine, and engineering where errors can have serious consequences. Even in everyday life, cooking with international recipes, understanding weather forecasts in different countries, or buying products sold in unfamiliar units all require reliable conversion tools.
Common Use Cases
- Cooking: convert recipe measurements between metric and imperial units
- Travel: understand distances, weights, and temperatures in foreign countries
- Science and engineering: convert between measurement systems for calculations
- Shopping: compare product sizes and weights when buying internationally
- Health and fitness: convert body weight and measurements between systems
Quick Conversion Tips
- ✓1 inch equals exactly 2.54 cm; 1 foot equals 30.48 cm
- ✓1 kg equals approximately 2.2 pounds; 1 pound is about 453.6 grams
- ✓To roughly convert Celsius to Fahrenheit, double the value and add 30
- ✓1 mile equals approximately 1.6 km; 1 km is about 0.62 miles
- ✓1 ounce equals approximately 28.35 grams
Frequently Asked Questions
How do I convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (or 1.8) and add 32. For example, 25C = (25 x 1.8) + 32 = 77F. For a quick estimate, double the Celsius value and add 30.
What is the difference between metric and imperial?
The metric system (used by most countries) is based on powers of 10 with units like meters, grams, and liters. The imperial system (used mainly in the US) uses units like feet, pounds, and gallons. The metric system is generally easier for calculations due to its decimal base.
Why does the US use the imperial system?
The US adopted the British imperial system during colonial times and has maintained it due to the high cost of conversion and public resistance to change. The US is one of only three countries that have not officially adopted the metric system, along with Myanmar and Liberia.
How accurate are these conversions?
Our conversions use standard conversion factors and are accurate to at least 4 decimal places. For most practical purposes, this level of precision is more than sufficient. Scientific or engineering applications may require additional significant figures.