Unit Converter Hub

Did you know? The meter was originally defined as one ten-millionth of the distance from the equator to the North Pole.

Quick Reference:

• • 1 mile = 1.609 kilometers (remember: "A mile is longer")
• • 1 inch = 2.54 centimeters (exactly)
• • 1 foot = 12 inches = 30.48 centimeters
• • Human height: typically 150-200 cm (5-6.5 feet)

Did you know? The kilogram was the last SI unit to be defined by a physical object (until 2019).

Quick Reference:

• • 1 kilogram = 2.205 pounds (about 2.2 lbs)
• • 1 pound = 16 ounces = 453.6 grams
• • 1 ton (metric) = 1,000 kilograms
• • Average adult: 60-80 kg (130-180 lbs)

Did you know? Fahrenheit set 0° as the coldest temperature he could create, and 100° as human body temperature (he was slightly off).

Quick Reference:

• • Water freezes: 0°C = 32°F = 273.15K
• • Water boils: 100°C = 212°F = 373.15K
• • Room temperature: ~20-22°C = 68-72°F
• • Body temperature: 37°C = 98.6°F

Did you know? The liter was originally defined as the volume of 1 kilogram of water.

Quick Reference:

• • 1 gallon (US) = 3.785 liters ≈ 4 liters
• • 1 cup = 236.6 milliliters (8 fluid ounces)
• • 1 liter = 1,000 milliliters = 1,000 cm³
• • Drinking: 2-3 liters (8 cups) water/day recommended

Did you know? An acre was historically the amount of land a yoke of oxen could plow in one day.

Quick Reference:

• • 1 hectare = 10,000 m² = 2.47 acres
• • 1 acre = 4,047 m² (about 208 × 208 feet)
• • 1 square mile = 640 acres = 2.59 km²
• • Soccer field: ~0.7 hectares (1.76 acres)

Did you know? The second is defined by the radiation of a cesium-133 atom, making atomic clocks the most accurate timekeepers.

Quick Reference:

• • 1 day = 24 hours = 1,440 minutes = 86,400 seconds
• • 1 year ≈ 365.25 days (hence leap years)
• • 1 week = 7 days = 168 hours
• • Human reaction time: ~200-300 milliseconds