Wednesday, January 15, 2014

Conversión de temperatura

Conversion of Temperature


Quick Celsius (°C) / Fahrenheit (°F) Conversion:

Conversion Tool
Just type a value in either box:
°C:    <=>   °F: 


Or this method:
°F to °CDeduct 32, then multiply by 5, then divide by 9
°C to °FMultiply by 9, then divide by 5, then add 32

Typical Temperatures

°C°FDescription
100212Water boils
40104Hot Bath
3798.6Body temperature
3086Beach weather
2170Room temperature
1050Cool Day
032Freezing point of water
-180Very Cold Day
-40-40Extremely Cold Day (and the same number!)
(bold are exact)

Explanation

There are two main temperature scales:
  • °F, the Fahrenheit Scale (used in the US), and
  • °C, the Celsius Scale (part of the Metric System, used in most other countries)
They both measure the same thing (temperature!), but use different numbers:
  • Boiling water (at normal pressure) measures 100° in Celsius, but 212° in Fahrenheit
  • And as water freezes it measures 0° in Celsius, but 32° in Fahrenheit
Like this:
Looking at the diagram, notice:
  • The scales start at a different number (0 vs 32), so we will need to add or subtract 32
  • The scales rise at a different rate (100 vs 180), so we will also need to multiply
And this is how it works out:
To convert from Celsius to Fahrenheit, first multiply by 180/100, then add 32
To convert from Fahrenheit to Celsius, first subtract 32, then multiply by 100/180

Note: 180/100 can be simplified to 9/5, and likewise 100/180=5/9, so this is the easiest way:
°C to °FMultiply by 9, then divide by 5, then add 32
°F to °CDeduct 32, then multiply by 5, then divide by 9

We can write that as a formula like this:
Celsius to Fahrenheit
(°C × 9/5) + 32 = °F
Fahrenheit to Celsius
(°F - 32) x 5/9 = °C

Example: Convert 26° Celsius (a nice warm day) to Fahrenheit

First: 26° × 9/5 = 234/5 = 46.8
Then: 46.8 + 32 = 78.8° F

Example: Convert 98.6° Fahrenheit (normal body temperature) to Celsius

First: 98.6° - 32 = 66.6
Then: 66.6 × 5/9 = 333/9 = 37° C

 

Other Methods That Work

Use 1.8 instead of 9/5

9/5 is equal to 1.8, so you could also use this method:
Celsius to Fahrenheit:
°C × 1.8 + 32 = °F
Fahrenheit to Celsius:
(°F - 32) / 1.8 = °C
To make "×1.8" easier you can multiply by 2 and subtract 10%, but it only works for °C to °F:
Celsius to Fahrenheit:
(°C × 2) less 10% + 32 = °F

Example: Convert 20° Celsius (A nice day) to Fahrenheit

  • 20x2 = 40
  • less 10% is 40-4 = 36
  • 36+32 = 68° F

Add 40, Multiply, Subtract 40

Since both scales cross at -40° (-40° C equals -40° F) you can:
  • add 40,
  • multiply by 5/9 (for °F to °C), or 9/5 (for °C to °F)
  • subtract 40

Example: Convert 10° Celsius (A cool day) to Fahrenheit

  • 10+40 = 50
  • 50×9/5 = 90
  • 90-40 = 50° F
To remember 9/5 for °C to °F think "F is greater than C, so there are more °F than °C"

Quick, but Not Accurate

Celsius to Fahrenheit:
Double, then add 30
Fahrenheit to Celsius:
Subtract 30, then halve
Examples °C → °F:
  • 0° C → 0+30 → 30° F (low by 2°)
  • 10° C → 20+30 → 50° F (exact!)
  • 30° C → 60+30 → 90° F (high by 4°)
  • 180° C → 360+30 → 390° F (high by 34°, not good)
Examples °F → °C:
  • 40° F → 10/2 → 5° C (almost right)
  • 80° F → 50/2 → 25° C (low by about 2°)
  • 120° F → 90/2 → 45° C (low by about 4°)
  • 450° F → 420/2 → 210° C (low by about 22°, not good)