Because that is the range of each channel in the eight-bit colour values the web uses. Two hundred and fifty-five of each gives white, and zero of each gives black.

Can I enter a hex value and adjust from there?

Not here — the sliders are the only input, so an existing colour is reproduced by setting its three channel values. The hex output lets you confirm you reached it.

Are the sliders relative or absolute?

Absolute. Each sets the channel's value rather than an amount to add, so adjustments are made by repositioning a channel and watching the swatch.

Why does raising green lead to yellow?

Because this is additive mixing. Red and green together produce yellow, green and blue produce cyan, and red and blue produce magenta — the secondary colours of a screen.

Why do the sliders move the colour so unevenly?

Because the sliders are absolute rather than relative and the channels are not perceptually even: green carries most of the brightness, so equal steps on the three sliders do not look like equal steps, and some colour changes are easy to hit this way while others, such as a pure hue rotation, are not.

RGB Channel Adjuster

R: 59G: 130B: 246

Result

#3b82f6

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The RGB channel adjuster sets a color by its red, green and blue values with three sliders from 0 to 255, showing the resulting hex value as you move them.

What is RGB Channel Adjuster?

The RGB channel adjuster is three sliders and a swatch.
Red, green and blue each run from zero to two hundred and fifty-five, the numbers used by every eight-bit colour value on the web, and the swatch beside them updates as they move, carrying its hex value and a copy button.
The starting point sits at a mid blue, with the channels at their corresponding values.

Working in channels rather than with a colour picker is not simply a slower way to do the same thing — it exposes different information, and it is the only way to adjust rgb values that have been specified as numbers. A picker encourages you to hunt for a colour by eye; three numeric sliders let you see the structure of a colour directly. Raising red while the other two stay fixed shows exactly how much of the final appearance that channel is responsible for, and because the three are independent, the effect of each is isolated. That makes the tool useful for learning as much as for producing.

It is also the right interface when the numbers are the requirement. Matching a value that has been specified channel by channel — from a hardware colour profile, a firmware configuration, a serialised settings file, or a colleague's specification — is a matter of typing three integers here rather than trying to land on them with a picker. Whether a colour appeared in a screenshot slightly off, or a device needs an exact channel triple, sliders set to whole numbers give exact control where dragging in a colour field gives approximate control.

The sliders are absolute rather than relative, which is the main thing to understand about the tool's behaviour.
There is no way to say add twenty to red; you set red's new value.
That means adjustments are made by repositioning each channel and watching the swatch, which is a different mental model from the lightness, saturation and hue tools in this domain where a slider expresses a change rather than a value.

A related limitation follows from working in channels: some things are easy to see and hard to name. Increasing green from a hundred and thirty to a hundred and eighty moves the colour clearly towards yellow-green, but nothing in the interface tells you what hue or saturation that represents. For calibration and matching, that is fine. For choosing a colour by intent, an HSL or perceptual tool expresses the adjustment more directly, and the format converter or the playground is the better starting point. There is also no hex input, so an existing value has to be re-created by reading its three channels and setting them — and the output shows the hex, so it is easy to check you landed on the right one.

Where it earns its place is precision work: reproducing an exact specification, debugging a colour that renders differently from the design, or teaching what each channel contributes. As an rgb color mixer it is the clearest of the mixing tools, because additive mixing of red, green and blue is literally what the three sliders are doing — pushing all three to the top gives white, pushing all three down gives black, and each pair in between produces one of the secondary colours. When the task is to set rgb channels to an exact triple, or to convert a known rgb value to hex, three sliders and a swatch do the job without any interpretation, and the channel numbers stay visible while you work rather than being hidden behind a hex field.

How to use RGB Channel Adjuster

Move the red, green and blue sliders, each from 0 to 255.
Watch the swatch change and check the hex value against the specification you are matching.
Copy the hex value once the channels are correct.

When to use RGB Channel Adjuster vs related tools

Use this when a colour is specified as channel values, or when you need to see how each channel contributes. Use the OKLCH playground or an HSL tool when you want to adjust by intent — lightness, vividness or hue — rather than by number. The CMYK channel mixer edits the same colour through the ink channels, and the HSL channel adjuster works the lightness and saturation axes instead of the raw channels.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.