I am not normally a GIS developer, I am just helping out with a bug and I am stumped on what is going on here, could I get some help please.

I have two calculations, one in 4326 (WGS84) and one in 3857 (Google Mercator). The coordinates were converted from 4326 -> 3857 and I have confirmed those are correct with ArcGIS and various online site conversion tools. The results I have are…

```
-114.50,38.0=-12746081.696,4579425.813
-114.00,40.0=-12690421.950,4865942.280
```

If I do an estimate of the area for 3857 by calculating the difference in the x and y points then multiplying the differences and dividing by 1 mil to get sq km, I get the result just under 16,000 sq km. Running SqlGeometry.STArea on a polygon bbox using these points this gives me a similar number.

If I convert the lat long to UTM I receive the numbers …

```
-114.50,38.0=719510.335753775,4208764.46330096
-114.00,40.0=243900.352021924,4432069.05663229
Excel Calculations
Easting Northing sq m sq km
719,510.3358 4,208,764.4633
243,900.3520 4,432,069.0566
--------------------------------------------------------------------
475,609.9837 223,304.5933 106,205,894,001.5610 106,205.8940
```

Sites used to convert to UTM

http://www.latlong.net/lat-long-utm.html

http://www.rcn.montana.edu/Resources/Converter.aspx

http://www.earthpoint.us/Convert.aspx

Running the same calculation of the difference and the area gives me the result of 106,205 sq km.

The code currently calculates the lat long by doing the following on a polygon of the bbox …

```
SqlGeography geog = SqlGeography.STGeomFromWKB(aoi.STAsBinary(), (int)aoi.STSrid);
area = (double)geog.STArea();
```

This gives me about 9,600 sq km.

**What I need to know…**

I am trying to find out which calculation is correct. I am leaning toward 3857 being correct as I the calculations give me approximatly the same numbers no matter how I do them. Since I feel that 4326 is incorrect, I would need a better way to calculate this in the current application (uses C# and SQLGeometry). If someone sees an error in my calculations please let me know and how to do this better if so.