How is the nearest name chosen?

Every entry in the 141-name table is compared against your colour by Euclidean distance in RGB, and the smallest distance wins. The search is exhaustive, so nothing is skipped.

Why does the default blue come back as royalblue rather than a closer-sounding name?

Because royalblue #4169E1 really is the closest table entry by RGB distance — 33 units away. No name in the list is closer, which is a limit of the table rather than of the match.

Is the distance a measure of how different the colours look?

No. It is raw RGB arithmetic, which ignores perception: a small distance can still look like a different colour, and a large one across two dark values can be hard to see. Use it to rank candidates.

Why do some grey colours come back with a different name?

The table carries the gray spelling only, so grey and darkslategrey are not candidates. A greyish value therefore settles on whichever gray-spelled or neighbouring entry is numerically closest.

Can it tell me whether the named colour is readable as text?

No. Naming and contrast are separate jobs here; send the foreground and background pair through the contrast checker for that answer.

Color Name Lookup

Color

#3B82F6

Nearest CSS named color

royalblue

#4169E1

RGB distance: 33

You Might Also Need

CSS Named Colors Reference

Browse and search the full CSS named-color list

Color Distance Calculator

Compute perceptual distance between two colors

The color name lookup finds the CSS name closest to any color you pick, shows that named swatch beside your value, and reports how far apart the two are in RGB distance.

What is Color Name Lookup?

The color name lookup answers one question — what is this color called? A colour goes in, either picked or typed into the field, and one answer comes back: the nearest css named color, drawn as a labelled swatch, with the rgb distance between your value and that name printed underneath it. It is a one-question page with a one-line answer, which is the point: naming a colour is a lookup rather than a judgement call.

The table it searches is the 141-name CSS list this domain uses everywhere else, aliceblue through yellowgreen.
Matching is nearest-neighbour by RGB distance: the red, green and blue channels are compared, squared and summed, and the smallest total wins.
The readout is three things at once — the name, the named colour's own hex value, and the distance rounded to a whole number.
The comparison is exhaustive, so the answer is the true nearest entry rather than an approximate one, and it is stable between visits and browsers.

Two details make the number worth reading. First, the metric is Euclidean in raw RGB, which is cheap but not perceptual: the default blue #3B82F6 snaps to royalblue #4169E1 at a distance of 33, while the pale grey-blue #E0E5EC snaps to lavender #E6E6FA at 15 — a smaller number, and a name that feels less accurate, because RGB distance does not know how eyes work. Second, the input is quantised before the search begins: a colour that arrived from a screenshot or a design export has already been rounded to whole 8-bit channels, so the comparison starts from that rounded value rather than the original.

Naming is also a translation step between teams. A developer reading the name of a color in a ticket has a roughly shared picture of what it means, while the same value written as hex is exact and unreadable at a glance; that trade — shared vocabulary against precise value — is the reason both spellings often end up in the same document, with the name for discussion and the hex for code.

The distance is a ranking device, not a measure of how different two colours look. Treat small numbers as a hint that the name is close, not as proof.
The table holds 141 names. British spellings such as grey and darkslategrey are absent, so a greyish value comes back as a gray-spelled name or as a different colour entirely.
Two values carry two names each: aqua and cyan share #00FFFF, fuchsia and magenta share #FF00FF. Either spelling can be returned for those values.
It names colours only. There is no readability check, no print accuracy and no transparency handling on this page.

Use it when a colour needs a human name — a ticket, an asset description, a note in a review — and treat the name as shorthand rather than as a value. Where the destination is code, copy the hex; where an exact name matters, read it from the named-colour table instead of trusting a snap; and where the real question is how far apart two chosen colours are, the distance calculator answers it directly rather than as a side effect of naming.

How to use Color Name Lookup

Set the colour with the picker field, or type a hex value and let the field normalise it.
Read the result card: the named swatch, its label and its hex value.
Check the RGB distance underneath to judge how close the match actually is.
Copy the hex for code, or quote the name when a human-readable label is what is needed.

When to use Color Name Lookup vs related tools

Use this when a colour needs a name for humans rather than a value for a compiler. The nearest named colour finder is the same lookup framed as a snapping step, the CSS named colours reference is the table to read from when the exact name matters, and the colour distance calculator measures the gap between two chosen colours instead of naming one.

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.