UnityCorrectLCID.cs

[System.Runtime.InteropServices.DllImport("KERNEL32.DLL")]
private static extern int GetSystemDefaultLCID();

private RegionInfo CurrentRegionInfo()
{
    var cultureInfo = new CultureInfo(GetSystemDefaultLCID());
    return new RegionInfo(cultureInfo);
}

// OR (it's preferable if Vista or higher)

[System.Runtime.InteropServices.DllImport("KERNEL32.DLL")]
private static extern int GetSystemDefaultLocaleName(byte[] buffer, int bufferSize);

private RegionInfo CurrentRegionInfo()
{
    var byteLength = 512;
    var bytes = new byte[byteLength];
    GetSystemDefaultLocaleName(bytes, byteLength);
    var currentCultureName = Encoding.Unicode.GetString(bytes);
    var cultureInfo = new CultureInfo(currentCultureName);
    return new RegionInfo(cultureInfo.LCID);
}

// OR (most correct way)

[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
private static extern int GetLocaleInfoEx(string localeName, Lctype lcType, byte[] buffer, int bufferSize);
[DllImport("kernel32.dll")]
private static extern int GetSystemDefaultLocaleName(byte[] buffer, int bufferSize);

public enum Lctype : uint
{
    LocaleImeasure = 0x0000000D,   // 0 = metric, 1 = inches (US)        
}

private int SystemMeasurmentCode()
{
    var buffer = new byte[128];
    GetLocaleInfoEx(GetCiLocale(), Lctype.LocaleImeasure, buffer, 128);
    return int.Parse(Encoding.Unicode.GetString(buffer));
}

private string GetCiLocale()
{
    var buffer = new byte[128];
    GetSystemDefaultLocaleName(buffer, 128);
    return Encoding.Unicode.GetString(buffer);
}