DMS Calc

This is a simple application to convert between decimal degrees (e.g. 27.125°) and degrees-minutes-seconds (e.g. 31° 8’ 15”).

Why This Even Exists

I encountered the need to perform this conversion when I was playing a lot of Kerbal Space Program using the MechJeb add on. Sometimes a required orbital element would be presented in one format but I’d need to enter the target orbital element in the other format.

The easiest way to do the conversion would be just to ask Google or any number of other online Javascript calculators to run the calculation. However, all of the calculators I found (including just asking Google) took the mathematically correct but computationally error-prone approach of ignoring the way computers do floating point math. The right way to go from decimal degrees to degrees-minutes-seconds is to take the fractional part, multiply it by 3600 to turn it into seconds, and then go from there. When I first looked around, I found everyone doing one floating point operation (either division or multiplication, depending on the direction of the conversion) and then passing the floating point result into another floating point operation (again, division or multiplication). This would lead to answers like 126.99999999999 degrees or 126 degrees, 60 minutes. It seems as though people have paid attention and nowadays, if you search for a calculator to do this, you’ll probably find one that gets it right. Still, you might find it handy to have a dedicated app just for this conversion that you can keep open, rather than having a browser tab.

Data Collected

If I collect data, then I have to store it, I have to secure it, I have to tell you about it, and I have to be prepared to delete it. That’s way too much work. Rather than do that, I don’t collect anything, and my life is better for it.

Support

I am not even sure what kind of support you might need for this app, but if you somehow do want to get in touch, everything you need is right here