Unit Conversion Reference 📏🔬

Comprehensive, accessible reference for all common unit conversions. Perfect for students, engineers, and anyone needing quick unit information.

Length / Distance 📐

UnitSymbolEquivalentCommon Use
Millimetermm0.001 m = 0.0394 inSmall measurements, rain
Centimetercm0.01 m = 0.394 inEveryday objects, height
Meterm1 m = 3.281 ft = 1.094 ydStandard SI unit, room dimensions
Kilometerkm1000 m = 0.621 miDistance between cities, roads
Inchin2.54 cm = 0.0254 mScreen size, imperial
Footft12 in = 30.48 cm = 0.305 mHeight, building dimensions
Yardyd3 ft = 0.914 mFootball field, fabric
Milemi5280 ft = 1.609 kmLong distances, roads (US)

Quick conversions: 1 m ≈ 3.3 ft | 1 km ≈ 0.62 mi | 1 in = 2.54 cm | 1 mi = 1.6 km

Temperature 🌡️

Celsius (°C)

  • • Water freezes: 0°C
  • • Room temperature: ~20-25°C
  • • Body temperature: 37°C
  • • Water boils: 100°C

°F = (°C × 9/5) + 32

Fahrenheit (°F)

  • • Water freezes: 32°F
  • • Room temperature: ~68-77°F
  • • Body temperature: 98.6°F
  • • Water boils: 212°F

°C = (°F - 32) × 5/9

Kelvin (K) - Scientific

Absolute temperature scale. 0 K = absolute zero (no molecular motion)

  • • Absolute zero: 0 K = -273.15°C = -459.67°F
  • • Water freezes: 273.15 K
  • • Room temperature: ~293-298 K
  • • Water boils: 373.15 K

K = °C + 273.15

°C°FKDescription
-40-40233Extreme cold
032273Water freezes
2068293Comfortable room
3798.6310Body temperature
100212373Water boils

Electrical Units ⚡

Voltage (V)

Electrical potential difference

  • • AA battery: 1.5 V
  • • Car battery: 12 V
  • • US household: 110-120 V
  • • Europe household: 220-240 V
  • • High voltage transmission: 500 kV

Current (A)

Flow of electrical charge (Amperes)

  • • USB charger: ~2 A
  • • Household circuit: 15-20 A
  • • Electric car charger: 32-80 A
  • • Lightning bolt: ~30,000 A

Power (W)

Rate of energy transfer (Watts)

  • • LED bulb: 8-15 W
  • • Laptop: 45-100 W
  • • Microwave: 1000-1200 W (1-1.2 kW)
  • • Electric car: 150-300 kW
  • • Power plant: 500-1000 MW

Power (W) = Voltage (V) × Current (A)

Energy (kWh, Wh, J)

Kilowatt-hour (kWh) - energy unit for electricity bills

  • • Smartphone battery: 10-20 Wh
  • • Laptop battery: 50-100 Wh
  • • Electric car battery: 50-100 kWh
  • • Average home/month: 800-1000 kWh

1 kWh = 1000 W for 1 hour = 3.6 MJ

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