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Unit Converter

Convert between units instantly. Length, weight, temperature, volume, area, speed, time, and more.

Complete Unit Conversion Guide

Unit conversion is essential for everyday life, science, cooking, travel, and international communication. Our comprehensive converter handles all common conversions between metric and imperial systems, temperature scales, and specialized units.

Common Conversions Quick Reference

Length: 1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 yard = 0.914 m, 1 mile = 1.609 km, 1 meter = 3.281 feet, 1 km = 0.621 miles.

Weight: 1 oz = 28.35 g, 1 lb = 0.454 kg, 1 kg = 2.205 lbs, 1 ton = 907 kg, 1 stone = 6.35 kg.

Temperature: °F = (°C × 9/5) + 32, °C = (°F - 32) × 5/9, Water freezes: 32°F = 0°C, Water boils: 212°F = 100°C.

Volume: 1 tsp = 5 ml, 1 tbsp = 15 ml, 1 cup = 237 ml, 1 pint = 473 ml, 1 quart = 946 ml, 1 gallon = 3.785 L, 1 liter = 1000 ml = 33.814 oz.

Metric vs Imperial Systems

The Metric System (SI Units)

Used by 95% of countries worldwide. Base-10 system making calculations simple: 1 km = 1000 m = 100,000 cm = 1,000,000 mm. Units include: Length (meter), Mass (gram/kilogram), Volume (liter), Temperature (Celsius). Advantages: logical base-10, easy mental math, scientific standard, international communication.

The Imperial System

Used primarily in United States. Non-uniform conversions: 12 inches = 1 foot, 3 feet = 1 yard, 5,280 feet = 1 mile. Units include: Length (inch, foot, yard, mile), Weight (ounce, pound, ton), Volume (cup, pint, quart, gallon), Temperature (Fahrenheit). Advantages: human-scaled (foot ≈ actual foot length), familiar to Americans, traditional measurement in some industries.

Frequently Asked Questions

How do you convert units?
Multiply value by conversion factor. Example: convert 10 miles to km. Factor: 1 mile = 1.609 km. Calculation: 10 × 1.609 = 16.09 km. Our calculator handles this automatically—just select units and enter value. For complex conversions (like miles per hour to meters per second), calculator applies multiple factors correctly.
Why does the US use imperial units?
Historical reasons. When metric system developed (1790s France), US was newly independent and already established with British imperial units. Switching would require massive infrastructure changes (road signs, construction standards, manufacturing). Several attempts to metricate failed due to cost and public resistance. Most US industries use metric internally (science, medicine, military), but consumer products remain imperial. This creates ongoing need for conversion tools.