# X, Y to GPS Coords... help a math dummy
**URL:** https://forum.kirupa.com/t/x-y-to-gps-coords-help-a-math-dummy/186010
**Category:** Uncategorized
**Created:** [April 18, 2006, 1:11pm UTC](https://forum.kirupa.com/t/x-y-to-gps-coords-help-a-math-dummy/186010 "2006-04-18T13:11:56Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@dragonfly](https://forum.kirupa.com/u/dragonfly)
#### Post date: [April 18, 2006, 1:11pm UTC](https://forum.kirupa.com/t/x-y-to-gps-coords-help-a-math-dummy/186010/1 "2006-04-18T13:11:56Z")
If im not mistaken, if I have a map of say, Wisconsin, and I know what the Latitude coords (degrees, hours, minutes) of the top and bottom of the map, and I know how many pixels tall the map is, then I should be able to convert, with math, degrees:hours:mins to pixels. (same thing with longitude, but lets just focus on one way first)
I would first find out how may hours (minutes would be over kill for my app) there are to a pixel. Thats pretty easy. But this gives me a decimal number. How do i convert a decimal value (like 10.25) back to degrees and hours (in other words, how do i make .25 a “60” based value)?
Ultimately, i want the user to be able to input coords in the form of degrees, hours, mins. Then convert that to X, Y (to place a marker on the map).
Has any one had experience with this or know how to do this? Probably just some easy math…right? :tb:
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### Author:  [@btibia](https://forum.kirupa.com/u/btibia)
#### Post date: [April 18, 2006, 1:24pm UTC](https://forum.kirupa.com/t/x-y-to-gps-coords-help-a-math-dummy/186010/2 "2006-04-18T13:24:14Z")
From what i now degrees, hours, minutes have this:
60" means 1’ and 60’ means 1\* so if you have 20.90 you have 21\*30’ ( i think it’s ok 🙂 )
U can use:
```auto
Math.round();
```
To transform the 20.90 to 21:) if a number it’s under x.50 it will change to x.00 and if its more then or equals with x.50 it will change to x+1.00
I hope i helped you.
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### Author:  [@dragonfly](https://forum.kirupa.com/u/dragonfly)
#### Post date: [April 18, 2006, 1:41pm UTC](https://forum.kirupa.com/t/x-y-to-gps-coords-help-a-math-dummy/186010/3 "2006-04-18T13:41:34Z")
good morning btibia (it’s morning here 🙂 )
Thank you for the reply, but I’m not sure how to follow what you replied with to a solution on my end. I understand Math.round… but i don’t understand how you’re converting a decimal number to degrees:hours:min (and in turn, converting a GPS coordinate into a X, Y position on an arbitrarily scaled map)
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### Author:  [@btibia](https://forum.kirupa.com/u/btibia)
#### Post date: [April 18, 2006, 2:23pm UTC](https://forum.kirupa.com/t/x-y-to-gps-coords-help-a-math-dummy/186010/4 "2006-04-18T14:23:31Z")
If you have an Atlas at home 🙂 take a small look, on every map they have a small SCALE. So you need to think like this (just a small exemple):
1degree = 10cm
Then if you have hours,minutes you go down with mm,etc.
And to change from cm to pixels use Adobe Photoshope 🙂
I found that 10cm = 283 pixels
I hope i helped you with something…i like this thread,so we can speak more here, until you finish the problem.
Good mornin!! 🙂