Color 101 / Color fundamentals
HEX, RGB & CMYK: what they mean and when to use them
You have found a color you love. Now which number should you copy? Start with where the design will be seen.
For websites, use HEX or RGB. For social images and other screen graphics, work in RGB and export for sRGB. For a printed piece, ask the printer for the required color profile and file settings before converting.
Three labels, two different jobs
HEX and RGB can describe the same screen color. CMYK describes amounts of printing ink. The useful distinction is between a color you display with light and a color you reproduce on a material.
| Format | What it describes | Use it for |
|---|---|---|
| HEX | RGB channels written in hexadecimal | Website styles, digital palette handoffs |
| RGB | Red, green, and blue light | Screen graphics, photos, web and app design |
| CMYK | Cyan, magenta, yellow, and black inks | Print production using a specified output profile |
One blue, written two ways
Take the blue from our rose palette. In CSS, #348ABF and rgb(52 138 191) specify the same sRGB color. Changing the notation does not change its brightness or improve its quality.
Split the six digits into pairs
- Red
34→ 52- Green
8A→ 138- Blue
BF→ 191
Hexadecimal uses 0–9 and A–F. Each pair runs from 00 to FF, equivalent to 0–255.
How RGB works
In this common 8-bit notation, each channel has a value from 0 to 255. All three at zero make black; all three at 255 make white. Higher numbers add more light in that channel. These numbers need a color space to have a precise meaning: CSS HEX and ordinary rgb() use sRGB. The same RGB numbers assigned to another profile can look different.
How HEX works
The six-digit form is #RRGGBB. Some colors also have a three-digit shorthand: #ABC expands to #AABBCC. Eight-digit HEX adds transparency as the last pair, so #348ABF80 is roughly 50% opaque. Uppercase and lowercase letters are equivalent.
“Clear Sky Blue” is our descriptive palette name. Use the numeric value to reproduce the screen color; a custom name by itself is not a color specification.
Try your own HEX
Paste a three- or six-digit HEX value to see its RGB channels and a simple CMYK estimate. This tool runs in your browser.
Why CMYK is a different decision
CMYK values are commonly written as four ink percentages. In a simplified model, more ink absorbs more light from the paper. Actual results depend on the inks, press, paper, and color profile. Paper white also becomes part of the design.
Our blue has a basic CMYK estimate of C73 M28 Y0 K25. A profile-based conversion in your design software can produce different values. Neither the formula nor a screen preview guarantees a match on a printed sheet.
Some vivid screen colors fall outside the range a particular printing process can reproduce. Conversion can change their appearance. Choose the printer’s output profile, soft-proof when available, and request a physical proof when the color matters. Avoid repeatedly converting the same master between RGB and CMYK.
Choose a workflow for the thing you are making
Copy HEX into your design
Use #348ABF for a border or accent. In CSS, either color: #348ABF; or color: rgb(52 138 191); is valid. Check text contrast separately: a correct color value does not make every color pairing readable.
Keep the screen version in RGB
Build your thumbnail in an RGB document. For a conventional web export, convert to sRGB and embed the profile when the export format and software support it. Inspect the exported image, not only the working document.
Ask the printer before exporting
Confirm paper, output profile, PDF requirements, bleed, and any ink limits. Keep an editable master and prepare a separate print copy using the agreed settings. Some printers accept RGB PDFs and handle conversion themselves; follow their specification.
A practical handoff for the rose palette
For a digital project, send the HEX values with the note “sRGB.” Include the RGB values if the recipient’s application asks for channels. For print, send the artwork and agreed production requirements rather than treating the website’s CMYK estimates as approved ink recipes.
Explore the rose palette
See the colors in a website, a poster, and packaging.
View palette →Common questions
Is HEX better quality than RGB?
No. The equivalent HEX and RGB values describe the same sRGB color. Choose the notation that fits your tool or handoff.
Why does the same image look different on two screens?
Displays differ in brightness, calibration, gamut, and viewing conditions. Color management helps interpret profiles consistently, but it cannot make every display identical.
Should every black element be C0 M0 Y0 K100?
Not automatically. Small black text is often specified as black ink only to reduce registration problems; large dark areas may use a printer-approved rich black. Ask the printer for their recommended values and ink limits.
Can I use the CMYK numbers from this site for final printing?
Use them as an approximate reference. Final ink values should come from your production workflow and the printer’s output profile, with a proof when needed.
References & further reading
This guide explains a practical workflow; the references below describe the underlying formats and color management.