Convert RGB to CMYK Red Green Blue ↔ Cyan Magenta Yellow Black Free Online Secure
Type a value in RGB and read it in CMYK at once. The arithmetic happens in your browser, nothing is sent anywhere, and what the conversion depends on is written out below rather than assumed.
Nothing uploaded
Where these notations come from
Hex and RGB are the same thing written twice. A screen colour is three numbers — how much red, green and blue light to emit — each from 0 to 255, which is one byte; hex simply writes those bytes in base sixteen, so #FF8800 and rgb(255, 136, 0) are the same instruction to the same pixel. HSL was invented because neither is readable by a human: it gives hue as an angle around a colour wheel, with saturation and lightness as percentages, so a designer can make something lighter without recomputing three figures. CMYK belongs to a different world altogether — ink rather than light. It is subtractive, built from four printing plates, and it cannot reach every colour a screen can, because a screen emits light while paper only reflects it.
Where you meet them
Hex is what you type into a stylesheet and what a design tool hands you. RGB appears wherever a colour needs arithmetic — gradients, transparency, code that computes a shade. HSL is what you reach for when adjusting a palette by hand, because the changes you want are usually changes of one of its three numbers. CMYK is what a printer asks for, and converting into it is the moment a design stops being light and becomes ink.
Questions people ask
Why does my CMYK result differ from what my printer gives me?
Because there is no single correct conversion. The arithmetic on this page is the simple, device-independent one, which is the right answer when you need a starting point or a rough equivalent. A print shop converts through a colour profile that accounts for the specific ink, paper and press, and the same RGB colour will produce different CMYK values on glossy stock than on uncoated. For anything that must match, ask the printer for their profile rather than trusting a formula.
Why can't some screen colours be printed?
Because the two cannot reach the same colours. A screen makes colour by adding light and can produce a vivid, saturated cyan or green that ink simply cannot match; paper makes colour by absorbing light, and the brightest it can ever be is the white of the page. The set of colours each can reach is called its gamut, and where they do not overlap, a conversion has to choose the nearest available colour. That is why a bright screen colour often looks slightly dulled in print.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Why you convert RGB to CMYK
Everything you design on a screen is made of light, red, green and blue, and every printed page is made of ink, cyan, magenta, yellow and black. At some point a colour has to cross from one world to the other. A logo drawn for a website must appear on a business card. A brand colour picked on a monitor has to be written into a form for the print shop. A client who knows only the screen values asks what they are in CMYK. To convert RGB to CMYK is the first step of that crossing: it turns the three numbers of a screen colour into the four percentages that a printer's plates work with.
It is important to say at the start what this conversion is and is not. It is a standard formula, the one nearly every web tool uses, and it gives a sensible starting point. It is not a promise of how the printed colour will look. Ink on paper and light on a screen are different things, and converting faithfully between them needs the profile of the press, of the paper and of your monitor. Without those, the numbers are a place to begin, and the print shop, which knows its own press, should set the final values. This page is honest about that, and the sections below explain what the formula does, what it leaves out and how to use the result well.
The calculation happens in your browser, and nothing is uploaded. Below you will find how the four percentages are obtained, why there is no single correct answer, what a printer will do with your numbers, the cases the formula cannot cover, and a short guide to preparing a colour for print.
How the conversion works
Light becomes ink
A screen mixes light by adding: red, green and blue together give white. Ink works the other way. Each ink absorbs some of the light that falls on the paper, and the more you add, the darker the result. Cyan absorbs red, magenta absorbs green and yellow absorbs blue. So the amount of cyan needed is, roughly, how much red is missing from the colour, and likewise for the others. That is the idea behind the formula.
The black plate
In principle, cyan, magenta and yellow together would make black. In practice they make a muddy brown, and they use a lot of ink. So printers add a fourth plate, black, called the key plate and abbreviated K. The formula works out the black first, from whichever channel is darkest: K = 1 − the largest of R, G and B, each taken as a fraction of 255. The remaining three are then calculated from what is left. This is how ink actually saves ink: wherever the colour is dark, black does the work instead of three coloured inks.
The example
For rgb(90, 70, 50), the largest channel is red at 0.353, so K = 1 − 0.353 = 0.647, which is 65%. Cyan is (1 − 0.353 − 0.647) ÷ 0.353 = 0%. Magenta is (1 − 0.275 − 0.647) ÷ 0.353 = 22%. Yellow is (1 − 0.196 − 0.647) ÷ 0.353 = 44%. The result is cmyk(0%, 22%, 44%, 65%), which is what the page shows for the starting colour.
What the conversion keeps and what it cannot
It keeps the colour as close as a formula can
The result is the colour as close as a formula can put it, and the four plates in the order a printer expects them: cyan, magenta, yellow and the black that carries the shadows. The black is worked out from whichever channel is darkest, which is how ink actually saves ink.
The honest limit: there is no single correct answer
This is the honest limit of the whole page. Ink on paper and light on a screen are different things, and converting faithfully between them needs the profile of the press, of the paper and of your monitor. Without those, what you get is the standard formula every web tool uses: good enough to pick a colour on screen, not good enough to send to a printer. Treat the numbers as a starting point and let the print shop set the final values.
Two more things the formula cannot carry
A rich black mixed from several inks comes back as plain K, because the formula does not know that you wanted four inks stacked. And a spot colour, one of the premixed inks such as those in the Pantone range, has no CMYK equivalent at all; the best a conversion can do is imitate it with four inks, and the imitation is only close.
Whole percents
Because the four numbers are written as whole percents, a colour taken across and back can land one step away: #5A4632 returns as #594632. The difference is invisible, but it means that the round trip is not exact. Keep the original RGB or hex as the master.
Why screens and printers disagree
Gamut
A screen can show some colours that no printer can reproduce, bright saturated blues, greens and oranges in particular, and a printer can reach a few tones, certain deep cyans, that a screen cannot. The overlap is large, but not total. When you convert RGB to CMYK, a vivid screen colour is moved to the nearest colour the inks can make, which is duller. This is called gamut mapping, and it is the reason a neon green on screen turns into a sober green on paper.
Paper
Coated paper gives bright, saturated colours; uncoated paper soaks up ink and makes the same numbers look softer and darker. Newsprint is more extreme. The same cmyk values are printed on all of them and look different on each, which is why the press profile matters.
Light
A screen shines; paper reflects whatever light falls on it. The same page looks different under daylight, an office tube and a warm lamp. Print professionals judge colour under standard lighting for exactly this reason.
Total ink
Each press has a limit on how much ink can be laid down in one place before the paper becomes too wet. Four inks at 100% would be 400%, far beyond most limits. The conversion's black keeps the total moderate, but dark colours, especially rich blacks, still need attention.
How to convert RGB to CMYK here
Type the three numbers
Enter the colour in the first field in the form rgb(90, 70, 50). Numbers from 0 to 255 are expected.
Read the four percentages
The answer appears at once in the form cmyk(0%, 22%, 44%, 65%), as cyan, magenta, yellow and black. They are whole percents, and the page shows the sentence so you can check it.
Use it as a starting point
Give the numbers to the print shop or enter them in your layout program as a first guess, and ask for a proof. If the proof differs from what you want, adjust the numbers, not the screen colour.
Where these notations come from
Hex and RGB are the same thing written twice
A screen colour is three numbers, how much red, green and blue light to emit, each from 0 to 255, which is one byte. Hex simply writes those bytes in base sixteen. If you start from a hex code, HEX to CMYK does both steps at once.
HSL and CMYK
HSL was invented because neither is readable by a human: it gives hue as an angle around a colour wheel, with saturation and lightness as percentages, so a designer can make something lighter without recomputing three figures. CMYK belongs to a different world altogether, ink rather than light. It is subtractive, built from four printing plates, and it cannot reach every colour a screen can, because a screen emits light while paper only reflects it.
Preparing a colour for print
Decide early
If a design will be printed, choose the colours with print in mind from the start. Colours that are in the gamut of both screen and press survive the crossing without surprises. Very bright neon tones do not.
Ask the printer for its profile
Most print shops publish an ICC profile for their presses and papers. Converting with the profile gives numbers tuned to that press, which are better than anything a web formula can produce. Use this page for orientation and the profile for the file you send.
Always ask for a proof
A printed proof, made on the real paper with the real press or a close simulation, is the only way to see the real colour. It costs a little and saves reprinting a thousand copies. Check it in daylight.
Mind small text in four colours
Fine black text should be printed in the black plate alone, not as a mix of four inks, because slight misalignment between plates would make the edges look coloured and fuzzy. A conversion that returns K only for black does the right thing here.
Traps when you convert RGB to CMYK
Believing the screen shows the print
It does not. The numbers are the same on any screen; the printed result depends on the press. Do not approve a colour from the monitor alone.
Converting twice
Going from RGB to CMYK and back loses information each time. Convert once, from the original RGB, and keep the original.
Expecting a spot colour
A brand colour defined as a Pantone ink will not be matched exactly by four process inks. Ask the printer whether to print it as a spot colour or to simulate it in CMYK.
Using the web conversion for a final file
The formula is for orientation. For a file that goes to a press, let the layout program convert with the printer's profile.
Questions people ask before converting
What is rgb(255, 255, 255) in CMYK?
cmyk(0%, 0%, 0%, 0%), no ink at all: the white of the paper.
What is rgb(0, 0, 0) in CMYK?
cmyk(0%, 0%, 0%, 100%), black ink only.
Why is there no single right answer?
Because the printed colour depends on the press, the paper and the light, and a formula knows none of them.
Will my screen colour print exactly?
Rarely. Bright saturated colours especially are duller in print.
Is my colour uploaded?
No. The arithmetic runs in your browser and nothing is sent anywhere.
How do I go back?
With CMYK to RGB, which turns the four percentages back into screen numbers.
Good practice when you convert RGB to CMYK
Convert RGB to CMYK once, at the end
Design in RGB as long as the work is on screen, and convert RGB to CMYK only when you prepare the file for print. Each conversion moves colours toward the printable gamut and cannot move them back. If you convert early and then edit, you carry the dull colours into every later version, including the web one.
Keep two masters
A brand with both web and print needs two reference sets: the RGB or hex values for screens and the agreed CMYK values for print. Keep them side by side in the brand sheet, with a note of which press and paper the CMYK was proofed on. Then nobody has to convert RGB to CMYK again for each new leaflet.
Watch the dark colours
Deep, saturated darks such as navy or forest green can come out of a naive conversion with a high total of ink, which dries slowly and may smudge. A good profile limits the total. If you convert RGB to CMYK for a dark colour by hand, ask the printer about their ink limit and keep the sum of the four percentages below it.
Use the black plate for neutrals
Greys and blacks should be built mostly from K, with little or no cyan, magenta and yellow. A grey made of three coloured inks drifts in colour when the press shifts slightly, while a grey made from black alone stays neutral. The formula on this page gives pure K for any true grey, which is what you want.
Check logos separately
A logo is the colour most likely to be scrutinised. Convert it, get a proof of the logo alone, and compare it with the screen version and with any previously printed material. Small differences that no one notices on a leaflet become obvious when the logo is placed next to an old one.
Related converters
The same family of tools covers the neighbouring conversions. To go back, use CMYK to RGB. For hex codes, there are HEX to CMYK and CMYK to HEX, and for the screen notations themselves, RGB to HEX, HEX to RGB and HEX to HSL. If your print job includes documents rather than colours, compress PDF and PDF to PNG help prepare files for sending.
A worked example
Say your brand colour on screen is rgb(30, 122, 92), a deep green, and you need to brief a printer. You type the numbers and read cmyk(75%, 0%, 25%, 52%). You write that on the job sheet as a starting point and add a note that the green must read as a deep, slightly cool green on uncoated stock. The printer prepares a proof with their own profile, the green comes out a little flatter than on the monitor, and you agree on cmyk(80%, 10%, 40%, 45%), which they save for future jobs. The screen number remains your master for the web; the agreed CMYK becomes the master for print.
A short checklist
Before converting
Know the paper and the press. Ask the printer for a profile if you can. Decide whether the colour is a process colour or a spot colour.
While converting
Type the three numbers, read the four percentages and note them as a starting point.
After converting
Order a proof, look at it in daylight and adjust the CMYK values rather than the screen colour.
Common mistakes
Approving colour on the monitor
Only a proof shows the real result.
Sending web-converted numbers as final
Use the printer's profile for the file you send.
Forgetting the black rule for text
Small black text belongs on the black plate alone.
Your colours stay on your device
The calculation happens locally. Your values are used by your own browser and nothing is sent anywhere. There is nothing to delete afterwards and no account to create. That is the plain way to convert RGB to CMYK.
Summary
To convert RGB to CMYK here, type the three numbers and read the four percentages at once. The result is the colour as close as a formula can put it, and the four plates in the order a printer expects them: cyan, magenta, yellow and the black that carries the shadows. There is no single correct answer, because ink on paper and light on a screen are different things, and converting faithfully needs the profile of the press, of the paper and of your monitor. Treat the numbers as a starting point and let the print shop set the final values. A rich black comes back as plain K, a spot colour has no CMYK equivalent, and whole percents mean a round trip can land a step away. Nothing is uploaded.