About the RGB to CMYK Converter
This converter changes a colour from RGB to CMYK. You type the RGB value into three number boxes for red, green and blue, and the CMYK value appears at once, together with a swatch so you can see the colour. Black (K) is 1 minus the largest channel, and each of cyan, magenta and yellow is worked out from its channel and K, then shown as a percentage. Out-of-range values are explained instead of being silently changed. The result can be copied with one tap. Everything is calculated in your browser, so nothing you type is uploaded.
Updated October 2026
How to use the RGB to CMYK Converter
- 1Enter the RGB value in the boxes.
- 2Watch the colour swatch change.
- 3Read the CMYK value in the large result box.
- 4Check the second line for the matching value in another notation.
- 5Press Copy result to keep it.
Why convert RGB to CMYK
Screens mix red, green and blue light, while printers mix cyan, magenta, yellow and black ink. When a colour from a screen design has to go to print, you need CMYK numbers. This conversion gives the standard starting values.
The same colour can be written in several notations, and each tool or file format prefers one. Having a quick converter means you do not have to guess or repeat the sum by hand when you move a colour from one place to another.
How the RGB to CMYK conversion works
Black (K) is 1 minus the largest channel, and each of cyan, magenta and yellow is worked out from its channel and K, then shown as a percentage.
For rgb(255, 136, 0) the largest channel is 255, so K is 0; cyan is 0, magenta is 1 − 136 ÷ 255 which is 47 percent, and yellow is 100 percent: cmyk(0%, 47%, 100%, 0%).
- Pure black is 0, 0, 0, 100 in CMYK.
- White is all zeros.
- Printed colours depend on the paper and inks.
Limits and good habits
Values outside the allowed range, such as an RGB channel above 255 or a percentage above 100, are rejected with a message. Round-trip conversions can drift by one unit because of rounding. If you need a colour to match exactly in print, use the profile supplied by your printer.
The Color Converter on this site shows HEX, RGB, HSL, HSV and CMYK together for one colour, and the Color Contrast Checker tells you whether two colours are readable together.
Phone and computer
On a phone, tap each box and type; the swatch and the CMYK value update as you go. On a computer the boxes sit on the left and the result on the right. The page works the same on both, and the Copy button gives you the value to paste into your design tool or style sheet. For the reverse use the CMYK to RGB Converter, and RGB to HEX Converter for web codes.
Features
- RGB to CMYK as you type
- Colour swatch
- Clear messages for values out of range
- Copy the result
- Private: nothing is uploaded
- Works on phone and computer
Frequently asked questions
How do I convert RGB to CMYK?
Black (K) is 1 minus the largest channel, and each of cyan, magenta and yellow is worked out from its channel and K, then shown as a percentage. For rgb(255, 136, 0) the largest channel is 255, so K is 0; cyan is 0, magenta is 1 − 136 ÷ 255 which is 47 percent, and yellow is 100 percent: cmyk(0%, 47%, 100%, 0%).
What is the RGB to CMYK formula?
Black (K) is 1 minus the largest channel, and each of cyan, magenta and yellow is worked out from its channel and K, then shown as a percentage.
What is rgb(255, 136, 0) as CMYK?
cmyk(0%, 47%, 100%, 0%). For rgb(255, 136, 0) the largest channel is 255, so K is 0; cyan is 0, magenta is 1 − 136 ÷ 255 which is 47 percent, and yellow is 100 percent: cmyk(0%, 47%, 100%, 0%).
Are the RGB to CMYK results exact?
The calculation is exact, but the values are rounded to whole numbers or whole percentages for display, so converting back and forth can differ by one unit.
Why does the colour look different on my screen and on paper?
Screens emit light and paper reflects it, and every screen and printer has its own profile. The converter gives the standard mathematical values; for print jobs, check a printed proof.
Is my input uploaded?
No. The conversion is done in your browser, and nothing is sent to a server.