<p>I got this formula for calculating-</p>
<p>100x(EXP.((17.625x32)/(243.04+32)/EXP.((17.625x54)/(243.04+54)))=?</p>
<p>The answer should be 43, but I Keep getting 65. Please, can anyone calculate this correctly?</p>
<p>Thank You!</p>

CC BY-SA 4.0
2021-10-04T15:51:26.300Z
Thanks, but no since I got the right formula, but I am having trouble doing math. I really need help to calculate with correct steps to get 43.
Rena
CC BY-SA 4.0
2021-10-04T16:51:26.123Z
I get 64. Are you sure you have the equation correct?
Fred
CC BY-SA 4.0
2021-10-04T17:25:39.907Z
Yes, the equation is correct. I use Exponential function incorrectly. I know that it is 2.71828 constant, but still get the wrong answer.
Rena
CC BY-SA 4.0
2021-10-04T18:49:49.543Z
@Jean I think the best link would really be [this one](https://earthscience.stackexchange.com/questions/20577/relative-humidity-approximation-from-dew-point-and-temperature)
JeopardyTempest
CC BY-SA 4.0
2021-10-04T18:50:51.413Z
It'd be best to say where you got the formula, so it's correctness can be better verified and mistakes more easily noticed?
JeopardyTempest
CC BY-SA 4.0
2021-10-04T19:01:29.097Z
Guessing from the numbers you use (32 and 54?), multiple RH calculators show that RH should be 44% if in Fahrenheit, or 31% if in Celsius, so it does seem the formula\usage is in err.
JeopardyTempest
CC BY-SA 4.0
2021-10-04T19:06:39.420Z
If your source was indeed [Relative Humidity approximation from Dew Point and Temperature](https://earthscience.stackexchange.com/questions/20577/relative-humidity-approximation-from-dew-point-and-temperature), I'm a bit suspicious of the author's "update", as it's not explicitly given in the paper.  However, it appears from skimming the paper that the formula likely should be using Celsius, so if you're in Fahrenheit, that may be a source of issues
JeopardyTempest
CC BY-SA 4.0
2021-10-04T19:07:40.743Z
If your issues are using their equation, next time please post a comment to their question (I'm not sure if you can with no reputation, but if you keep using StackExchange, you will be able to soon) or in [Chat](https://chat.stackexchange.com/?tab=site&host=earthscience.stackexchange.com).
JeopardyTempest
CC BY-SA 4.0
2021-10-04T19:18:56.163Z
Your parentheses above look wrong, it would put the second EXP inside the first, rather than doing two separately.  It does look like if you follow the layout of the linked RH question just above, it gives the correct answer (32% for the given numbers in Celsius).  (Convert to Celsius before using the equation if in F to get right answer)
JeopardyTempest
CC BY-SA 4.0
2021-10-04T20:04:31.280Z
@JeopardyTempest Actually the oldest seems to be this one: https://earthscience.stackexchange.com/q/14899/18081 Anyway, the question has been asked (and answered) multiple times.
Jean-Marie Prival
CC BY-SA 4.0
2021-10-04T21:30:06.887Z
But he wants to calculate RH not temp/dew point, so although they're related my link is a lot more direct... plus the formula looks to come from the question I link to  :-)
JeopardyTempest
CC BY-SA 4.0
2021-10-04T23:30:27.790Z
Solved it already in a different way! Thanks for responding though!
Rena
CC BY-SA 4.0
2021-10-05T02:18:40.077Z
@Rena the goal of the site is to provide one's learning for the next person to benefit from. So if it was something useful, perhaps post it as an answer here or on the [Relative Humidity approximation from Dew Point and Temperature](https://earthscience.stackexchange.com/questions/20577/relative-humidity-approximation-from-dew-point-and-temperature) question so others can benefit. Generally questions with a user-centric bug is being made get closed and no answers because they aren't of use to a larger group... but I tried to be of help. Seems the least you could do is tell us what changed :)
JeopardyTempest
<geography><mathematics>
How to calculate relative humidity with temperature and dew point?
Rena
# How to calculate relative humidity with temperature and dew point?

(Asked by: username_0 on 2021-10-04)

I got this formula for calculating-

100x(EXP.((17.625x32)/(243.04+32)/EXP.((17.625x54)/(243.04+54)))=?

The answer should be 43, but I Keep getting 65. Please, can anyone calculate this correctly?

Thank You!

**Tags:** geography, mathematics

> **Comments:**
> **username_0**: Thanks, but no since I got the right formula, but I am having trouble doing math. I really need help to calculate with correct steps to get 43.  
> **username_1**: I get 64. Are you sure you have the equation correct?  
> **username_0**: Yes, the equation is correct. I use Exponential function incorrectly. I know that it is 2.71828 constant, but still get the wrong answer.  
> **username_2**: @Jean I think the best link would really be [this one](https://earthscience.stackexchange.com/questions/20577/relative-humidity-approximation-from-dew-point-and-temperature)  
> **username_2**: It'd be best to say where you got the formula, so it's correctness can be better verified and mistakes more easily noticed?  
> **username_2**: Guessing from the numbers you use (32 and 54?), multiple RH calculators show that RH should be 44% if in Fahrenheit, or 31% if in Celsius, so it does seem the formula\usage is in err.  
> **username_2**: If your source was indeed [Relative Humidity approximation from Dew Point and Temperature](https://earthscience.stackexchange.com/questions/20577/relative-humidity-approximation-from-dew-point-and-temperature), I'm a bit suspicious of the author's "update", as it's not explicitly given in the paper.  However, it appears from skimming the paper that the formula likely should be using Celsius, so if you're in Fahrenheit, that may be a source of issues  
> **username_2**: If your issues are using their equation, next time please post a comment to their question (I'm not sure if you can with no reputation, but if you keep using StackExchange, you will be able to soon) or in [Chat](https://chat.stackexchange.com/?tab=site&host=earthscience.stackexchange.com).  
> **username_2**: Your parentheses above look wrong, it would put the second EXP inside the first, rather than doing two separately.  It does look like if you follow the layout of the linked RH question just above, it gives the correct answer (32% for the given numbers in Celsius).  (Convert to Celsius before using the equation if in F to get right answer)  
> **username_3**: @username_2 Actually the oldest seems to be this one: https://earthscience.stackexchange.com/q/14899/18081 Anyway, the question has been asked (and answered) multiple times.  
> **username_2**: But he wants to calculate RH not temp/dew point, so although they're related my link is a lot more direct... plus the formula looks to come from the question I link to  :-)  
> **username_0**: Solved it already in a different way! Thanks for responding though!  
> **username_2**: @username_0 the goal of the site is to provide one's learning for the next person to benefit from. So if it was something useful, perhaps post it as an answer here or on the [Relative Humidity approximation from Dew Point and Temperature](https://earthscience.stackexchange.com/questions/20577/relative-humidity-approximation-from-dew-point-and-temperature) question so others can benefit. Generally questions with a user-centric bug is being made get closed and no answers because they aren't of use to a larger group... but I tried to be of help. Seems the least you could do is tell us what changed :)  

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