Which flags look alike

How this is measured

At build time, each of the 195 flag SVGs is rasterised to a small 64x48 bitmap, and two things are read from it. Every pair is then scored; the page only displays the result.

1. Colour.Each pixel’s colour is quantised into one of 27 buckets (3 levels per red/green/blue channel), giving the share of the flag in each bucket. Two flags’ colour similarity is the overlap of those shares. The buckets are deliberately coarse so slightly different shades — two reds, two blues — still count as a match.
2. Structure.From the same bitmap: the band orientation (horizontal, vertical, or neither), a 3×3 grid of average colours, and whether a busy central emblem is present. Structure similarity rewards matching orientation, close grid colours, and matching emblem presence.

The overall index is 0.55 × colour + 0.45 × structure, and structure is itself 0.4 orientation + 0.45 grid + 0.15 emblem. These weights are constants, shown here on purpose: change them and the neighbours change.

What it does not measure

This is a computed measure by the method above, not an objective fact. The number is our similarity index from 0 to 100 — never a claim that two flags are “X% identical”. It says nothing about a flag’s meaning, history, or symbolism, and it does not read exact colour codes: hex values are not verified anywhere on this site. A colour-weighted index like this one groups every red flag with a small emblem together; a structure-weighted one would pull them apart. There is no single right answer to “which flags look alike” — this is one disclosed, reproducible answer, and a different weighting would give different neighbours. More on how this site handles what it knows.