How to Estimate Celsius Temperatures in Fahrenheit

Most countries use Celsius as a unit of measurement for calculating the temperature. Many online applications will precisely convert Celsius into Fahrenheit but if you don’t have access to the Internet, use the following techniques to give you a good estimate.

Method 1
Method 1 of 3:

Estimating an Approximate Temperature

  1. Image titled Estimate Celsius Temperatures in Fahrenheit Step 1
    1
    Determine the temperature. Look for a temperature display. Many public clocks display the temperature below the time. Ask someone to tell you the temperature if you cannot locate a thermometer or temperature display.
  2. Image titled Estimate Celsius Temperatures in Fahrenheit Step 2
    2
    Multiply the temperature by 2. Use a calculator or simply multiply the numbers in your head. Either way, you want to double this number.
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  3. Image titled Estimate Celsius Temperatures in Fahrenheit Step 3
    3
    Add 30 to this number. Take the doubled number and add 30 to it. Make use of a calculator or perform the addition in your head. This will give you an approximate temperature in Fahrenheit.[1] For example:
    • Determine the temperature in Celsius: 20 degrees
    • Multiply this number by two: 20 x 2 = 40
    • Add thirty to this number: 40 + 30 = 70 degrees Fahrenheit
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Method 2
Method 2 of 3:

Estimating a Semi-Precise Temperature

  1. Image titled Estimate Celsius Temperatures in Fahrenheit Step 4
    1
    Determine the temperature. Find a temperature display. Look for a public clock on a building such as a bank. Many public clocks also display the temperature below the time. Ask someone to tell you the temperature if you cannot locate a thermometer or temperature display.
  2. Image titled Estimate Celsius Temperatures in Fahrenheit Step 5
    2
    Multiply the temperature by 2. Use a calculator or simply multiply the numbers in your head. Either way, you want to double this number.
  3. Image titled Estimate Celsius Temperatures in Fahrenheit Step 6
    3
    Subtract 10% from this number. Calculate 10% by multiplying the number by 0.1. For example, 100 x 0.1. = 10. Subtract this number from the number you doubled in the first calculation. Use a calculator to perform these operations for best results.
  4. Image titled Estimate Celsius Temperatures in Fahrenheit Step 7
    4
    Add 32 to this number. Take the doubled number and add 32 to it. Make use of a calculator or perform the addition in your head. This will give you a semi-precise temperature in Fahrenheit.[2] For example:
    • Determine the temperature in Celsius: 20 degrees
    • Multiply this number by two: 20 x 2 = 40
    • Determine ten percent of this number: 40 x 0.1 = 4
    • Subtract this number from your number in step two: 40 – 4 = 36
    • Add thirty-two to this number: 36 + 32 = 68 degrees Fahrenheit
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Method 3
Method 3 of 3:

Memorizing Key Numbers

  1. Image titled Estimate Celsius Temperatures in Fahrenheit Step 8
    1
    Learn rough comparable temperatures by heart. These numbers are easy to memorize and will allow you to make quick conversions. Memorize Celsius to Fahrenheit using multiples of 10:
    • 0 degrees Celsius equals 32 degrees Fahrenheit.
    • 10 degrees Celsius equals 50 degrees Fahrenheit.
    • 20 degrees Celsius equals 68 degrees Fahrenheit.
    • 30 degrees Celsius equals 86 degrees Fahrenheit.
    • 40 degrees Celsius equals 104 degrees Fahrenheit.
  2. Image titled Estimate Celsius Temperatures in Fahrenheit Step 9
    2
    Learn comparable temperatures by heart. These numbers are fairly easy to memorize and will allow you to make precise conversions. Memorize Celsius to Fahrenheit using multiples of 5:
    • -5 degrees Celsius equals 23 degrees Fahrenheit.
    • 5 degrees Celsius equals 41 degrees Fahrenheit.
    • 15 degrees Celsius equals 59 degrees Fahrenheit.
    • 25 degrees Celsius equals 77 degrees Fahrenheit.
    • 35 degrees Celsius equals 95 degrees Fahrenheit.
  3. Image titled Estimate Celsius Temperatures in Fahrenheit Step 10
    3
    Learn comparable temperatures by heart. Memorize Fahrenheit to Celsius using multiples of 10 to perform rough conversions:
    • 32 degrees Fahrenheit equals 0 degrees Celsius.
    • 40 degrees Fahrenheit equals 4.4 degrees Celsius.
    • 50 degrees Fahrenheit equals 10 degrees Celsius.
    • 60 degrees Fahrenheit equals 15.5 degrees Celsius.
    • 70 degrees Fahrenheit equals 21.1 degrees Celsius.
    • 80 degrees Fahrenheit equals 26.6 degrees Celsius.[3]
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Community Q&A

  • Question
    What's a quick method to convert Celsius to Fahrenheit?
    Donagan
    Donagan
    Top Answerer
    There's only one method. See Convert Celsius (°C) to Fahrenheit (°F).
  • Question
    C = 5/9 (F - 32). 113 F - 32 = 81 x 5/9 = 45 C. Is this correct, does 113 Fahrenheit = 45 degrees Celsius?
    Donagan
    Donagan
    Top Answerer
    Yes, that's correct.
  • Question
    If increase in Celsius is 23, what's the increase in Fahrenheit?
    Donagan
    Donagan
    Top Answerer
    Each Celsius degree is equivalent to 1.8 Fahrenheit degrees. 23 multiplied by 1.8 equals 41.4.
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Warnings

  • The quick method is a good estimate only within a range of temperatures normally felt by the human body. The estimation becomes less accurate the further from this range you go.
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References

  1. ↑ http://lifehacker.com/5917331/quickly-convert-between-fahrenheit-and-celsius-without-a-calculator
  2. ↑ http://www.aaamath.com/mea414x2.htm
  3. ↑ http://www.asknumbers.com/tables%5Ccelsius_to_fahrenheit_conversion_table.png

About This Article

wikiHow Staff
Co-authored by:
wikiHow Staff
wikiHow Staff Writer
This article was co-authored by wikiHow Staff. Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been viewed 154,817 times.
43 votes - 82%
Co-authors: 21
Updated: August 4, 2020
Views: 154,817
Categories: Meteorology | Conversion Aids
Article SummaryX

To estimate a Celsius temperature in Fahrenheit, multiply the temperature by 2, then add 30 to that number. This will give you an approximate temperature in Fahrenheit. If you need a more precise estimate, multiply the temperature by 2, then subtract 10% and add 32 to that number. The result will more closely represent the Celsius to Fahrenheit conversion. For help memorizing a few Celsius to Fahrenheit conversions, keep reading!

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