GIMP

• 1). Launch GIMP. Click the "Foreground Color" box, and the Change Foreground Color guide opens in its own window.
  
  
• 2). Click the "Printer" tab located at the top of the window; this tab corresponds to the CMYK color model and shows you each of the four value percentages.
  
  
• 3). Click inside the R field, which is on the right side of the window, and insert the first value you have for your RGB color code. Input the G and B values you have as well. The CMYK value percentages automatically changes when you adjust the RGB values. Write down the CMYK percentages for archival purposes.
  
  
• 4). Adjust the RGB values again, as desired, to convert a different RGB color code into a CMYK value.
  
  

JavaScripter Color Converter

• 1). Visit JavaScripter.net, click on "JavaScript FAQ" and then on "Colors."
  
  
• 2). Click on the question "How do I convert RGB color values to CMYK representation of the same color?" You are taken to the color converter page.
  
  
• 3). Insert R, G and B values into the corresponding fields and click on the "Convert to CMYK" button. The C, M, Y and K fields auto-complete based on the RGB equivalent.
  
  

Forret Color Conversion

• 1). Visit Web.Forret.com and click on "Color Converter." The conversion tool page loads, containing fields for CMYK and RGB values.
  
  
• 2). Double-click within the R field and enter your first value, and then double-click in the G and then B fields to replace those values with the codes of the color you want to convert.
  
  
• 3). Click the "RGB to CMYK" icon, and the page reloads with corresponding value percentages in the CMYK fields.