Three Axes · Five Hairline Shapes

Forehead ratio test

RealSmile Research Team · Facial Analysis Specialists
Updated May 19, 2026
Based on 5 peer-reviewed sources
→ See our methodology

Height, width, hairline shape. Three axes scored against the Farkas anthropometric reference band.

The 0.30 to 0.36 height ratio band defines the published reference range. The test returns where your forehead sits and which axis is the deviation.

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The three axes the test measures

Height ratio. Vertical distance from hairline to brow ridge divided by total face length (hairline to chin tip). The published reference band sits at 0.30 to 0.36, meaning the forehead is one-third or less of total face length. Above 0.36 reads as tall; below 0.30 reads as compressed.

Width ratio. Horizontal distance between the two temple landmarks divided by cheek width. The reference band sits at 0.92 to 1.05. Below 0.92 narrows the upper face toward diamond classification; above 1.05 widens toward heart or oblong.

Hairline shape. Classification into one of five categories: straight, rounded, widow\'s peak, M-shaped, or asymmetric. The shape interacts with the height ratio: an M-shaped hairline adds 0.02 to 0.04 to the perceived height ratio depending on recession depth.

The five hairline shapes

Straight

Near-horizontal line across the forehead. Reads as defined and balanced. Most common in adolescent and young-adult faces; can shift with age.

Rounded

Gentle convex curve. Common feminine-coded hairline. Pairs well with most cuts. Hairstyle goal is usually to maintain visible boundary rather than hide it.

Widow's peak

Central downward point. Genetic, present from birth or adolescence. Reads as distinctive. Can be styled with center part or fringe depending on the face shape.

M-shaped

Front-corner recession on both sides. Usually a sign of progressive recession. Pharmacological intervention (finasteride, minoxidil) can slow or partially reverse early stages.

Asymmetric

One side measurably higher than the other. Most common cause is hair growth pattern; some asymmetry is normal. Hairstyle goal is usually to balance with a side part on the higher side.

The levers that change visible forehead read

Hairstyle. The single largest free lever. A fringe, undercut with volume on top, or middle part each shifts the apparent height by 10 to 20 percent. The right cut for a 0.38 height ratio is different from the right cut for a 0.32 height ratio; the report ranks options against your specific number.

Brow shaping. The brow defines the lower boundary of the forehead. A higher, thinner brow line increases visible forehead height; a fuller, lower brow line reduces it. Brow shaping is the second-largest free lever, often producing a 5 to 10 percent shift in apparent height ratio.

Recession reversal. If the hairline is M-shaped or has progressed beyond the published reference, evidence-based treatments (finasteride, minoxidil, low-level laser therapy, PRP) can slow or partially reverse early-stage recession over 6 to 12 months. The recession reversal lowers the hairline measurably and reduces the height ratio.

Honest limits

Forehead ratio test FAQ

What does a forehead ratio test actually measure?+
A clean forehead test measures three axes. First, height ratio: the vertical distance from hairline to brow ridge, expressed as a fraction of total face length. The published reference band sits at 0.30 to 0.36 (Farkas anthropometric norms). Second, width ratio: the horizontal distance between the two temple landmarks, expressed as a fraction of cheek width. The reference sits at 0.92 to 1.05. Third, hairline shape classification: straight, rounded, widow's peak, M-shaped (front-corner recession), or asymmetric. The combination of the three returns a forehead score and a hairline category.
What counts as a "big forehead" on the actual ratio?+
On the published norms, a forehead is "high" when the height ratio exceeds 0.36 (the top of the reference band, equal to one upper third that is taller than the other two). Above 0.40 reads as visibly tall. The casual perception of "big forehead" usually combines a height ratio above 0.36 with either a receded hairline or a narrow temple width that increases the apparent height. The ratio matters more than the absolute centimeter measurement because the same height reads very different on a small face versus a long face.
Does forehead size affect attractiveness?+
On the published research, forehead height interacts with facial-thirds proportion rather than mattering on its own. Cunningham (1986) and Perrett, Lee, Penton-Voak et al. (1998) found facial thirds at approximately equal heights (each third within 0.30 to 0.36 of total face) correlated with higher attractiveness ratings. Outside that band, the forehead being either visibly taller or visibly shorter than the middle and lower thirds reduced ratings. The effect is not large in isolation; it is one input into the overall facial harmony signal that drives larger downstream rating effects.
Can I change my forehead size?+
Bone structure (frontal bone height, supraorbital ridge projection) does not change in adults. Three soft-tissue and grooming levers shift the visible forehead read. First, hairline framing: a fringe, undercut, or middle part changes the apparent height by a measurable amount (often 10 to 20 percent of visible height). Second, brow shaping: a higher brow line increases apparent forehead height; a fuller, lower brow line reduces it. Third, in cases of frontal hair recession, treatments that slow or partially reverse the recession (finasteride, minoxidil, low-level laser therapy, PRP, transplant) can lower the hairline and reduce the height ratio. The bone does not change; the visible boundaries change.
What about forehead width specifically?+
Forehead width below 0.92 of cheek width shifts the face shape classification toward diamond (narrow forehead, widest at cheeks, narrow jaw). Forehead width above 1.05 shifts toward heart (wider forehead than jaw with pointed chin) or oblong (similar widths top to bottom). The width is structural and stable; what changes is the perceived width through hairstyle volume. A side part with volume on top increases perceived forehead width; a tight cut with low volume reduces it.
How does the hairline shape classification work?+
The test classifies the hairline into one of five categories. Straight: a near-horizontal line across the forehead. Rounded: gentle convex curve. Widow's peak: a central downward point. M-shaped: noticeable front-corner recession on both sides. Asymmetric: one side measurably higher than the other. The shape interacts with the height ratio: a straight hairline with a height ratio at 0.35 reads as proportional; an M-shaped hairline at the same height ratio reads as recessed and adds 0.02 to 0.04 to the perceived height ratio depending on the recession depth.
Why does my forehead look different in different photos?+
Three photo variables shift apparent forehead size by a measurable amount. Camera height above eye level extends the apparent forehead and shortens the chin (the classic "long-forehead selfie"). Hair styled forward versus back changes the visible hairline boundary. Lighting from above casts shadow on the brow ridge and increases the apparent height. The 17-metric scan normalizes for camera pose using facial landmark geometry. Casual selfie comparisons will mislead you about real change; the scan does not.
What does the $14.99 PDF unlock for forehead ratio?+
The free test returns the three axis values with percentile against population norms plus the hairline shape classification. The $14.99 report adds a written interpretation of how the forehead interacts with the middle and lower thirds, ranked hairstyle picks for your specific height and width configuration with examples, brow-shaping recommendations for the brow-to-forehead boundary, and a 30-day action plan for the levers that move the visible read on your specific configuration.

Three axes. Five hairline shapes. Hairstyle picks calibrated to yours.

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$14.99 unlocks the full 17-metric PDF: height and width values with percentiles, hairline classification, ranked hairstyle picks, and 30-day action plan.

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