Every face shape guide reads like maths homework. Measure your forehead. Divide by your jaw. Show your working. No one has the time or energy for that, so we skipped all the fluff. All you need is a mirror and two minutes.

STEP ONE: WORK OUT YOUR FACE SHAPE

Pull your hair back off your face. Stand close to the mirror, look straight ahead and keep your chin level. If you have a lipstick or a whiteboard marker you don't care about (and you don't mind cleaning your mirror after), trace the outline of your face on the mirror, from hairline to chin. Step back and look at the shape you drew. It's easier to judge a shape on glass than on your own face. No marker, or can't be bothered messing up your mirror? Take a selfie, front on, hair back, phone held at eye level. Not above your head. That's a different kind of photo. Now answer these three questions.

1. Is your face about as long as it is wide, a bit longer, or clearly longer?

Look at the distance from hairline to chin, then across your face at its widest point.

2. Where is your face widest?

Your forehead, your cheekbones, or about the same all the way down?

3. What does your jaw do?

Does it curve softly, have corners you can see just below your ears, or narrow to a small chin?

What your answers mean

Round | About as long as it is wide. Widest at the cheekbones, with full cheeks. Jaw curves softly.

Square | About as long as it is wide. Same width all the way down. Jaw has corners.

Oval | A bit longer than it is wide. Widest at the cheekbones, only just. Jaw curves softly.

Heart | A bit longer than it is wide. Widest at the forehead. Jaw narrows to a small chin.

Diamond | A bit longer than it is wide. Widest at the cheekbones, clearly. Jaw narrows to a small chin.

Oblong | Clearly longer than it is wide. Same width all the way down. Jaw can go either way.

Still not sure? Most people are a mix of two. Pick the two shapes you're closest to and look for a frame that shows up in both. Or ask the friend who always tells you the truth. Everyone has one.

STEP TWO: UNDERSTAND THE ONE RULE

Frames work by contrast. Your face has a shape, and the frame should balance it, not copy it.

Soft, round face: a frame with angles adds structure.
Sharp, angular face: a frame with curves softens it.
Long face: a tall lens or a wide front interrupts the length.
Wide at the forehead: weight at the bottom of the frame evens it out.
Wide at the cheekbones: curves that follow them, or a stronger brow to add width up top.
Balanced face: almost anything works. Good for you.

That's it. Everything below is that rule applied to six faces.

Full cheeks, no strong angles, width and length about the same. Round frames just repeat it. This face needs contrast, not more of the same.

Reach for Boston. Structured, and it has the longest temple in the range, so it suits larger heads. On a smaller head, or if Boston isn't your fave, Ryker does the same job. Vincent and Roux both work too. Or go square with Harlow. Paloma brings a flat brow and a tall lens. Outer Limits and Kinetic do it with sharper angles.

Forehead, cheekbones and jaw all roughly the same width. A strong, defined jawline. This face doesn't need more structure. It needs softening.

Aura rounds off what's already sharp. Orion does the same with a shorter lens height. Want more presence, try Bobbi or Siena. Or commit fully and go round with Elio. Orion and Siena have shorter temples, so they sit best on smaller heads.

Balanced proportions, face a touch longer than wide. The wildcard shape. This is where the rules loosen, because almost everything works. Lucky you.

Aura is the safe pick. Balanced front, standard lens height, nothing to correct. Want more angle, go Kinetic or Diamond. Want more structure, Boston adds it without overwhelming anything. Prefer something slimmer, Odessa has one of the shortest lens heights in the range. Want something with more edge, Rogue is the only wrap in the range.

Forehead widest, narrowing to a smaller chin. The goal is to put weight low on the face, not add more up top.

Bobbi is the strongest match. A teardrop aviator, fullest at the bottom of the lens, which is exactly where this face wants the width. Orion, Lourdes and Stevie work too. Soft ovals and rounds, nothing that cuts a hard line across the brow.

Narrow forehead, wide cheekbones, narrow jaw and chin. The widest point is the cheekbones, not the forehead. Not the same as heart shaped. Don't mix the two up.

Orion or Siena both follow the natural curve of the face instead of fighting the cheekbone width. Want something stronger, a heavier brow adds width where this face is narrowest. The Void, Boston, Atlas and the new Paloma all do it.

One thing worth knowing. This isn't a pitch for our style literally named Diamond. That one's geometric, all straight lines and hard angles, which is the wrong direction for a diamond face. Easy mix up, given the name.

Longer than it is wide, with the forehead, cheekbones and jaw all similar widths and straight sides. This face has length to spare. The frame's job is to interrupt it, not add to it.

The Void or Bobbi bring width across the middle of the face. Harlow does the same job differently, with a tall lens that breaks up the length. Paloma goes taller again, with a 49mm lens height. Rogue pairs a tall lens with the most curved lens in the range. Paloma and Rogue both have shorter temples, so they sit best on smaller heads.

Can round faces wear round sunglasses?

Generally, no. Round on round doubles down on the shape instead of balancing it. Square and rectangle frames suit better.

Do aviators suit every face shape?

Depends which one. Bobbi, the teardrop, suits square, heart and oblong faces. Atlas suits round, oval and diamond. The Void and Paloma suits round, diamond and oblong. Check the shape, not the category.

What's the difference between a heart shaped and diamond face?

Heart shaped is widest at the forehead. Diamond is widest at the cheekbones. Different widest point, different frame, check which one's actually yours before you shop.

Rules are a starting point. Not a life sentence.

Try them on. You'll know.