18 degrees Fahrenheit equals approximately 263.15 kelvin.
To convert a temperature from Fahrenheit to kelvin, you first convert it to Celsius, then add 273.15, which is the absolute zero offset in kelvin. This method ensures temperature values are shifted from the Fahrenheit scale to an absolute scale used in science.
Conversion Tool
Result in kelvin:
Conversion Formula
The formula to convert Fahrenheit (°F) to kelvin (K) is:
K = (°F – 32) × (5/9) + 273.15
This formula works by first converting Fahrenheit to Celsius using (°F – 32) × 5/9, because Celsius and Fahrenheit scales are offset by 32 and differ by a factor of 9/5. Then, 273.15 is added to convert Celsius to kelvin, since kelvin starts at absolute zero, which is -273.15°C.
For example, converting 18°F:
- Subtract 32: 18 – 32 = -14
- Multiply by 5/9: -14 × 5/9 = -7.7778
- Add 273.15: -7.7778 + 273.15 = 265.3722 K
Conversion Example
-
Convert 50°F to kelvin:
- Subtract 32: 50 – 32 = 18
- Multiply by 5/9: 18 × 5/9 = 10
- Add 273.15: 10 + 273.15 = 283.15 K
-
Convert 0°F to kelvin:
- Subtract 32: 0 – 32 = -32
- Multiply by 5/9: -32 × 5/9 = -17.7778
- Add 273.15: -17.7778 + 273.15 = 255.3722 K
-
Convert 100°F to kelvin:
- Subtract 32: 100 – 32 = 68
- Multiply by 5/9: 68 × 5/9 = 37.7778
- Add 273.15: 37.7778 + 273.15 = 310.9278 K
Conversion Chart
| Fahrenheit (°F) | Kelvin (K) |
|---|---|
| -7.0 | 263.706 |
| 0.0 | 255.372 |
| 5.0 | 258.706 |
| 10.0 | 262.039 |
| 15.0 | 265.372 |
| 18.0 | 266.483 |
| 20.0 | 267.039 |
| 25.0 | 270.372 |
| 30.0 | 273.706 |
| 35.0 | 277.039 |
| 40.0 | 280.372 |
| 43.0 | 282.039 |
The chart helps to quickly find kelvin values without calculation by matching Fahrenheit values in the left column, then reading corresponding kelvin results on the right. Use it when approximate conversions needed fast.
Related Conversion Questions
- What is 18°F in kelvin with decimal precision?
- How to convert 18 degrees Fahrenheit to kelvin step-by-step?
- Is 18 Fahrenheit above or below freezing in kelvin?
- How does 18°F compare to room temperature in kelvin?
- What formula converts 18°F into kelvin properly?
- Why does 18°F convert to about 266 kelvin?
- Can 18°F be negative in kelvin scale?
Conversion Definitions
Fahrenheit: Fahrenheit is a temperature scale, mostly used in the United States, where water freezes at 32 degrees and boils at 212 degrees under standard atmospheric pressure. The scale divides the temperature range between freezing and boiling into 180 degrees increments.
Kelvin: Kelvin is the SI unit of temperature used in science, based on absolute zero, the coldest possible temperature. It starts at zero kelvin (-273.15°C), where atoms stop moving. Unlike Celsius and Fahrenheit, kelvin does not use degrees symbol.
Conversion FAQs
Can kelvin temperatures be negative when converting from Fahrenheit?
No, kelvin scale starts at absolute zero, which is zero kelvin. Any temperature converted from Fahrenheit to kelvin will never be negative, because absolute zero is the lowest physical temperature possible.
Why add 273.15 after converting Fahrenheit to Celsius?
The 273.15 is added because kelvin is based on the absolute zero point, which is -273.15°C. After converting from Fahrenheit to Celsius, adding 273.15 shifts the scale so that zero kelvin represents absolute zero.
Is the conversion formula always accurate for scientific use?
The formula provides exact mathematical conversion between Fahrenheit and kelvin scales, suitable for scientific and everyday purposes. However, precision depends on using correct constants and decimal places, and rounding might cause small differences.
How does the Fahrenheit scale relate to kelvin physically?
Fahrenheit is a relative temperature scale based on water’s freezing and boiling points, while kelvin is absolute, starting at absolute zero. The physical meaning behind kelvin reflects molecular motion, unlike Fahrenheit which is arbitrary.
Can this conversion be used for weather temperatures?
Yes, converting Fahrenheit to kelvin can be used for weather data, but kelvin is mostly used in scientific contexts. Weather temperatures are usually reported in Celsius or Fahrenheit for public understanding.