Run your photo through three AI face shape detectors and there is a fair chance you will get three different answers. That is not a fault in any one of them — it is what happens when a tool measures a three-dimensional face from a two-dimensional image, with no fixed distance, angle or lighting to work from. This face shape detector takes a different route. It starts from four measurements you take yourself with a tape or a mirror, which removes the camera from the equation entirely, and it shows you the ratios behind the result so you can see why it landed where it did. A photo option exists if you would rather not measure, but the measurement mode is the one we would use.
Short answer: Your face shape comes from four measurements — forehead, cheekbones, jawline and face length. If all three widths are close and the length is about one and a half times the cheekbone width, that is an oval. If the length is close to the width, that is round or square depending on the jaw.
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How to know your face shape comes down to two comparisons: which of your three widths is largest, and how the length relates to the width. Everything else is naming. The six below are the standard set used across eyewear, hairdressing and makeup, each with its geometric alternative name. Read the ratios first and the name second — the ratio is what determines which frames sit level and which haircuts balance the line.
Face length about one and a half times the cheekbone width, with forehead slightly wider than the jaw and a softly rounded jawline.
All three widths sit close together with the cheekbones marginally widest, and the length gives the face a gentle vertical line. Oval is the shape most frame and haircut guides use as their reference point, which is why oval faces are so often told that everything suits them — the guides were drafted around this proportion in the first place.
Face length and cheekbone width close to equal, with a soft jawline and widths that are similar to one another.
The distinguishing feature is that length and width are nearly the same, and the jawline curves rather than angles. Round and square faces share that length-to-width ratio and are separated entirely by the jaw: a soft curve reads round, a defined corner reads square.
Length and width close to equal, with forehead, cheekbones and jaw all similar and a strong, angular jawline.
The three widths run almost parallel and the jaw is the defining feature — clearly corner-shaped rather than curved. Square and round faces are frequently confused by photo-based tools, because a camera flattens the jaw angle that separates them.
Forehead is the widest measurement, narrowing through the cheekbones to a noticeably narrower, often pointed chin.
The width decreases steadily from top to bottom. A widow's peak hairline is common but not required — the measurement that matters is forehead against jaw, and a heart shape has a clear difference between the two.
Cheekbones are the widest measurement, with both the forehead and the jaw noticeably narrower, and the face longer than it is wide.
The widest point sits in the middle rather than at either end. Diamond is the least common of the six and the one most often misidentified as heart or oval, because the difference lies in whether the forehead or the cheekbones lead.
Face length clearly greater than one and a half times the cheekbone width, with the three widths close to one another.
Essentially a lengthened square or oval: the widths are balanced but the vertical measurement dominates. This is the shape where the length measurement does all the work, and skipping it is the most common reason an oblong face is read as oval.
Most faces are not a clean example of one shape. Around a third of people sit between two categories, and the styling advice for neighbouring shapes overlaps almost entirely.
Short answer:
Photo-based detectors have no fixed scale. A camera flattens depth, lens distance changes proportions, tilt alters the jawline, and hair hides the hairline. Each tool also sets its own boundaries between shapes. The measurements remove all four problems at once.
This comes up constantly and nobody addresses it. Upload the same selfie to three face shape analyzers and you can get oval, heart and diamond back. People reasonably conclude that one of the tools is broken, or that their face is somehow unclassifiable. Neither is true. The tools are attempting something genuinely difficult, and the difficulty is structural rather than a matter of better software.
Start with scale. A photograph contains no unit of measurement. A face shape detector from photo can see that your cheekbones are wider than your jaw, but not by how much in absolute terms, so it works entirely in proportions inferred from the image. Change the distance between you and the lens and those proportions change with it — a phone held at arm's length compresses a face differently from one held close, which is the entire reason selfies distort noses. Two photos of the same person at different distances can genuinely produce different ratios.
Then add angle and light. A few degrees of head tilt shortens the apparent face length. A downward camera angle widens the forehead and narrows the jaw, which reads as heart. Overhead lighting casts shadow under the cheekbones and exaggerates their width, which reads as diamond. Hair covering the temples hides the forehead measurement entirely and the tool estimates it. None of these are exotic conditions — they describe most selfies.
Finally, there is no agreed boundary. Fashion has no standards body for face shape, so each tool decides for itself how close two widths must be to count as equal, and how long a face must be before oval becomes oblong. One tool's oval is another's oblong at exactly the same ratios. We publish ours in the methodology section below, which at least lets you see the rule that produced your result rather than taking a word on trust.
A photo has no unit of measurement, only proportions.
Arm's length and close-up produce different ratios.
Tilt shortens the face; shadow widens the cheekbones.
Each tool sets its own cut-off between shapes.
A tape measure has none of these problems.
Short answer:
Measure the widest point of your forehead, the widest point across your cheekbones, the width of your jaw from angle to angle, and the length from hairline to chin. A soft tape or a piece of string against a ruler both work.
Measure across the widest part of the forehead, which is usually halfway between the eyebrows and the hairline. Pull your hair back first — this is the measurement most often guessed at, and guessing it is what separates a heart result from an oval one.
Measure from the pointed bone just below the outer corner of one eye, straight across to the same point on the other side. Keep the tape flat against the face rather than following the curve, since a curved reading will be too large.
Measure from the angle of the jaw below one ear to the same point on the other side, passing under the chin. If you cannot find the jaw angle, clench lightly — the corner becomes obvious. This is the measurement that separates round from square.
Measure straight down the centre from the hairline to the tip of the chin. If your hairline is uneven or receded, measure from the point where it sits at the centre of the forehead. This is the measurement that identifies an oblong face, and the one most often left out.
Take each twice. A quarter of an inch changes the result more often than people expect, which is also why photo-based tools disagree so readily.
Use a piece of string or a phone charging cable, mark each measurement with your thumb, then lay it against a ruler. Or skip measuring entirely and use the quiz — it asks four questions about what you see in a mirror and gets most people to the same answer.
Short answer:
Pull your hair back, stand in front of a mirror, and answer four questions about which part of your face is widest, how your jaw is shaped, and whether your face reads longer than it is wide. It takes under a minute and lands most people in the right category.
A face shape quiz will never be as precise as four measurements, and anyone claiming otherwise is overselling. What it does have going for it is that your own eyes have none of the problems a camera does — you see your face at a fixed distance, in three dimensions, from the angle you actually look at it. For a great many people that is enough to get to the right answer, and it is considerably more reliable than uploading a selfie.
Answer what you see rather than what you have been told. A surprising number of people have carried around a face shape they were assigned once by a hairdresser or a filter and never checked. Pull your hair fully back, face the mirror straight on rather than at an angle, and take each question at face value.
Forehead · Cheekbones · Jaw · They look about the same
Softly rounded · Angular with clear corners · Narrow or pointed · Somewhere between
Clearly longer · Slightly longer · About the same · Wider than it is long
Pointed · Rounded · Square or flat · Not especially defined
Four questions, no photo, no email, nothing stored.
Short answer:
The photo mode exists because plenty of people would rather not measure. It is the least accurate of the three methods for the reasons set out above. Your image is processed and discarded, never stored, and no account is required.
A face shape detector online that asks for an upload is the format most people expect, so we have built one. We have also put it third in the list rather than first, because it is the method most likely to give you an answer that changes when you try again. If you use it, the conditions matter more than the tool does: face the camera straight on, hold the phone at eye level rather than above, pull your hair completely back from the temples and jaw, use even light from the front, and keep a neutral expression with a closed mouth.
Two photos taken under different conditions will frequently disagree, and when they do, the measurements are the tie-break. If a photo result surprises you, take the four measurements before accepting it.
Your image is used to detect the four facial proportions and is then discarded. It is not stored on our servers, not added to any training data, not linked to you, and no account is created. Nothing about your face is retained after the result is returned. If you would rather not upload anything at all, the measurement and quiz modes reach the same answer with no image involved. Our privacy policy sets this out in full.
Short answer:
The working principle is contrast. Angular frames on a round or oval face, rounded frames on a square or oblong face, and frames no wider than the widest part of the face. Fit matters more than shape: a frame that sits level and does not slide is doing most of the work.
Choosing glasses is the single most common reason people look up their face shape, and the advice given is usually reduced to a lookup table. The table is not wrong, but the principle underneath it is more useful than the table: frames read best when their line contrasts with the line of the face. A softly curved face takes a defined frame; a strongly angular face takes a softer one. That is the whole rule.
Proportion is the second half. A frame wider than the widest part of your face will make everything below it look narrower, and a frame that sits above or below your brow line will cut the face horizontally in a place it does not naturally divide. Both of those matter more than whether the shape is technically suited to your category.
The practical caveat is that frame fit beats frame shape every time. A frame that slides down, sits crooked or pinches at the temple will look wrong regardless of how well its shape matches your face on paper. Bridge width and temple length are measured in millimetres and printed inside the arm of every pair — those three numbers are worth knowing before the shape is.
This chart sets the six face shapes side by side so the differences are visible in one place. The comparisons are the same ones the tool uses.
The difference between round and square is the jawline. The difference between oval and oblong is the length. Those two comparisons separate four of the six shapes.
Frame silhouettes, brow line alignment, and the contrast principle.
Cuts that balance vertical lines, soften angles, and frame proportions.
Face shape has no standards body behind it, and the tools that classify it almost never publish their rules. Here are ours, and their limits.
Three comparisons produce the result. First, which of the three widths is largest — forehead, cheekbones or jaw — and by how much, with a difference under five per cent counted as balanced. Second, the ratio of face length to cheekbone width, where about 1.5 is the centre of the oval range and clearly above it moves into oblong. Third, the jawline, which separates round from square at equal length and width. Those boundaries are conventions rather than standards, and a tool using different cut-offs is not wrong — it is simply using a different convention without saying so.
Our calculation model evaluates bilateral symmetry across the upper, middle, and lower thirds of the facial contour. By comparing cheekbone breadth against forehead spread and jawline angle within five per cent intervals, the ratios reflect classical geometric balancing points used in European styling and millinery traditions.
Because it is the only mode with a fixed scale. A photo contains proportions but no units, and those proportions shift with lens distance, head angle, lighting and hair. Four measurements taken with a tape have none of those variables. The photo mode uses the same facial landmark approach the detector tools are built on, which is well-documented technology, but the limitation is not in the landmark detection — it is in what a single two-dimensional image can tell you about a three-dimensional face.
Focal length distortion in smartphone cameras commonly magnifies central features and narrows peripheral edges, introducing artificial variance that calipers or tape measures completely eliminate.
Four situations. Faces sitting within a couple of percentage points of a boundary, which is roughly a third of people and is why we name the neighbouring shape rather than pick one. Receded or uneven hairlines, where the length measurement has no clean starting point. Photo mode under any of the conditions described above. And any use of the result beyond choosing frames, haircuts and earrings — a face shape category describes proportions and carries no information about anything else.
Natural human facial asymmetry also means one cheekbone or jaw corner may sit marginally higher, which is why averaging two passes across the facial planes yields the most repeatable result.
For a plain editorial explanation of the six shapes with no tool attached, Byrdie's guide to identifying your face shape is among the clearest available. For the technology underneath photo-based detection, MediaPipe Face Landmarker documentation describes the facial landmark model most of these tools are built on, including what it can and cannot resolve.
THE SIX SHAPES
How to Know Your Face Shape: The Six Categories
Oval
Round
· Also called: Circle
Square
Heart
· Also called: Inverted triangle
Diamond
Oblong
· Also called: Rectangle, long
THE PART NOBODY EXPLAINS
Why Three AI Face Shape Detectors Give You Three Different Answers
No scale
Lens distance
Angle and light
No agreed boundary
HOW TO MEASURE
Taking the Four Face Measurements
All four lines labelled on line-drawn face
01 Forehead width
02 Cheekbone width
03 Jawline width
04 Face length
No tape measure?
NO TAPE MEASURE?
Face Shape Quiz: Four Questions in a Mirror
Take the quiz
Pulling your hair back, which part of your face looks widest?
How would you describe your jawline?
Does your face look longer than it is wide?
How does your chin look?
THE PHOTO OPTION
Using a Photo, and What Happens to It
What happens to your photo
EYEWEAR
What Is My Face Shape for Glasses?
Four Primary Frame Silhouettes
Round
Rectangular
Cat-eye
Aviator
FACE SHAPE
FRAMES THAT SUIT
WHY
Oval
Most shapes
Balanced proportions take contrast in either direction
Round
Rectangular, square, angular
Straight lines contrast with curves
Square
Round, oval, rimless
Curves soften a strong jaw line
Heart
Bottom-heavy, rimless, cat-eye
Weight lower down balances a wider forehead
Diamond
Cat-eye, oval, rimless
Detail at the brow draws the line upward
Oblong
Deep frames, oversized, decorative temples
Height breaks up the vertical line
AT A GLANCE
Face Shape Chart: The Six Types Compared
SHAPE
WIDEST POINT
LENGTH VS WIDTH
JAWLINE
ALSO CALLED
Oval
Cheekbones, slightly
About 1.5×
Softly rounded
—
Round
Cheekbones
About equal
Curved, soft
Circle
Square
All three similar
About equal
Angular, defined
—
Heart
Forehead
Longer than wide
Narrow, often pointed
Inverted triangle
Diamond
Cheekbones, clearly
Longer than wide
Narrow
—
Oblong
All three similar
Clearly over 1.5×
Varies
Rectangle, long
STYLE GUIDES
How to Use Your Result
EYEWEAR
Glasses for Your Face Shape
HAIR
Hairstyles by Face Shape
METHODOLOGY
How This Detector Works
What this face shape detector is built on
Why the measurement mode is the default
Where this detector is least reliable
