The five-second face-shape test
Tie your hair back, face a mirror and trace the outline of your face with a bar of soap or your finger in the fog. Compare width at the forehead, cheekbones and jaw, and the length-to-width ratio.
Roughly equal width everywhere plus a length about 1.5× the width reads oval. Wide cheekbones with a narrow forehead and jaw reads diamond. Wide jaw with a square hairline reads square. You are looking for the widest zone — that is what the shape name describes.
What each shape wants from a haircut
Round faces want vertical lines and height: side parts, high volume on top, off-the-face lengths. Square faces want softness: waves, curls and layered fringes round out strong angles.
Oval faces are the universal donors — most cuts work, so the decision becomes taste. Heart faces benefit from weight at the jaw: chin-length bobs and side-swept fringe. Oblong faces want width: waves, curtain bangs, never a towering top with shaved sides.
Where the classic advice fails
Rules of thumb assume average hair density, a straight parting and neutral lighting. Your reality includes cowlicks, a receding hairline, glasses, your typical camera angle and how your hair behaves on day three without washing.
That is why a static "best styles for your shape" list is only the first filter — the second filter should always be your own face, with the style actually rendered on it.
The two-filter method
Filter one: shape logic. Shortlist three or four candidates using the guide above. Filter two: photorealistic try-on. Render each candidate on your selfie, compare them side by side in the editor, and keep the one your eyes — not the article — believe.
3xrun exists precisely for filter two. It takes the abstract rules and turns them into a picture of you, which is the only picture that ever mattered.