Thread: Convert Dew Point formula to Excel?

Hi,

I have been struggling to get the attached formula to calculate correctly in Excel - I'm sure its dumbo issue - any help is much appreciated :-)

The aim is to use a temperature value (C) and a Relative Humidity value (%) to give Dew Point Temperature.

For example:

T RH Dew
17.38 66.54 11.08

Thanks Martin - I will have a go at this - much bigger formula - perhaps more accurate.

The given expression looks pretty straightforward. When you say it doesn't calculate correctly, what do you mean? Is it giving you an error value? An incorrect, but close value? An incorrect value that has nothing to do with reality?

If it helps, when I'm building an equation like this, I like to put each element of the function in its own cell. So, I would have input cells for a, b, T, and RH. Then a cell for gamma. And a final cell that calculated Td. by breaking the expression up into smaller "bites," each cell is easier to program, and easier to debug.

Of course, what we all seem to want is a single cell that contains the whole function. When this is the case, having broken it up into pieces, I find it easier to then combine pieces until I get the whole function into one cell.

Hi, sorry, you're quite right - not enough info. The value I'm getting is not right - I have broken the equation down into three parts as follows:

C3 = Temp value
D3 = RH value

K3 =237.7*(SQRT(C3*D3))
L3 =17.271-(SQRT(C3*D3))
M3 =K3/L3

Got it - I wasn't reading the formula correclty - thanks and sorry :-)