Frames and Face Shapes: Which of the Five Numbers the Label Moves

Five numbers size a frame, and three of them are stamped

A pair of glasses is sized by five numbers. Three are printed inside the temple: lens width, bridge width and temple length, normally as 54 □ 18 - 145. The other two are not printed anywhere. Total width runs from the outermost point of one end piece to the outermost point of the other. Lens depth is the vertical height of the opening at its tallest. A shop can measure both, and an online order often cannot.

The three stamped numbers have published adult bands: 40 to 60 mm for lens width, 14 to 24 mm for bridge width, 120 to 150 mm for temple length, with 140 to 145 mm the common run. None of those bands is written per outline. They are ranges for adult heads and noses, which is why the same 54 □ 18 - 145 can appear on a frame sold to a round face and on one sold to an oblong face without either page contradicting itself.

Table 1 puts the five rows beside the part of the body each one follows. Read the second column first: two of the five cannot be found on the frame at all, and those are the two a shape label has anything to say about.

Stamped means printed inside a temple arm, normally as lens width, bridge width and temple length. Total width and depth are measured, not stamped. The 130 – 145 mm width ladders are not one measurement: the same figures are used in the sources read for this page for a hinge-to-hinge span and for the front's full width, and at a 136 mm target the two readings sit 13 to 20 mm apart on the published medians. The depth row is this site's published ceiling at a 136 mm cheekbone line, not a shelf size; section three shows how the seven outlines spread inside it. Inches, where a table gives them, are the millimetre value divided by 25.4.

What the outline changes, and what it leaves alone

The outline enters the width row, but it does not enter as a number. It enters as a line: the front has to reach the widest line of the face. For six of the seven outlines that line is the cheekbone. Heart is the exception above a quotient of 0.97, where the forehead is as wide as the cheekbones or wider and the front has to clear the higher line. Triangle is the exception at the other end: its jaw is the widest point, and its published band puts the jaw at 0.96 to 1.20 of the cheekbone. The tape decides which line binds; the label only tells you where to put it.

Depth is different. It is the one row where the outline prints a different number, and the number is a ceiling: at a 136 mm cheekbone line, 44 mm for round and square, 47 for heart and triangle, 48 for diamond and oval, 51 for oblong. That is a 7 mm spread across the whole set.

Two comparisons keep that 7 mm in proportion. The first is your width. Hold the outline still and move the cheekbone line from 128 to 148 mm: the round ceiling goes from 41 to 48 mm, the oblong from 47 to 56. Your width moves the ceiling about as hard as your outline does. The second is the order form. The charts that print lens heights at all print them at 40, 43, 46 and 50 mm, so the seven ceilings buy three stocked heights: 43 mm for round and square, 46 for heart, diamond, oval and triangle, and 50 for oblong. The entire shape effect, spent at a counter, is one or two rungs.

What the outline does not change is the other four rows. Not one page in Table 3 attaches a different lens-width band, bridge band or temple band to an outline, and the total-width row is a line to measure rather than a number to copy. The shape word tells you which line of your face is the binding one. It does not tell you a millimetre.

Eyeglass frames for face types, in one table

That phrase usually introduces a list of styles: round frames for a square face, angular frames for a round one, cat-eye for a heart. That advice is about line and contrast, and this page does not repeat it. What can be tabulated is the fitting side: which line the front must reach, and how much vertical room the outline leaves for a lens.

Table 2 lays the seven outlines across those two columns. The fourth column says what the outline changes in the fitting numbers, and in five of the seven rows that is the depth ceiling and nothing else. The table is worked at one cheekbone line, 136 mm, a round figure chosen just inside this site's 128.2 to 148.8 mm adult band, whose midpoint is 138.5 mm; the depth column moves with width, so use it as a ceiling for that width rather than a universal number.

Read the first and last columns together. Heart and triangle are the two outlines whose width line can move off the cheekbone, and they move in opposite directions: heart up to the forehead, triangle down to the jaw. Diamond and oval share a ceiling of 48 mm and differ in why: diamond's forehead and jaw are both narrower than its cheekbones, while an oval face is simply a long outline with the cheekbones as its widest point. Round and square share 44 mm because their mean length-to-width ratios are identical in this site's rule set; the difference between them is a corner at the jaw, which no frame measurement on the inside of a temple arm records.

Depth is a ceiling, not a shelf size. The figures are this site's arithmetic from published mean ratios and a six-millimetre brow allowance this site sets itself, worked at 136 mm, a round figure just inside the 128.2 to 148.8 mm adult band; the band's midpoint is 138.5 mm. They are not measurements of any frame. Snapped to the heights the trade stocks, the seven ceilings buy three rungs: 43, 46 and 50 mm. Triangle's 47 mm sits on a rounding boundary and is quoted from the published table rather than re-derived here. Inches are the millimetre value divided by 25.4.

The end piece moves the width row more than the label does

The width row is the one a face label is supposed to govern, and it is also the row the record agrees about least. Total width is a sum: twice the lens width, plus the bridge, plus an end-piece allowance across both sides. Call the allowance R. The identity is T = 2A + DBL + R. The first two terms are stamped; R is not. It is the width of the rim and hinge outside the lens, and it is the term the record has rewritten.

Three published readings of R do not agree. A July 2026 fitting guide puts it at 3 mm per side, 6 mm across the front. A retailer's rule of thumb puts the two outer rims at 5 to 8 mm. A frame-specification comparison, reading 3,942 retailer records, published medians of 20 mm for acetate, 16 for plastic, 15 for titanium and 13 for metal in August 2026; a re-read of the same page in September 2026, over different samples for each material, returned 15, 14, 14 and 12 mm. The difference between the first reading and the last is 9 mm on the same 54 □ 18 stamp: 132 mm with 6 mm of allowance, 141 mm with 15.

Nine millimetres is more than the entire 7 mm depth spread across seven outlines. The construction of the front, its material and the width of its rim, moves the width row by more than the face label moves any row. That is not an argument that shape is useless. It is an argument about order: measure the front, read the stamp, and calculate R before choosing a label, because the label's contribution is smaller than a term that is not printed.

It also explains why two guides can give different width advice for the same face and both be describing real frames. One is measuring a hinge span, one a front, one the inside of the rim. Add a 6 mm allowance to one calculation and a 20 mm allowance to another and the difference compounds. The number a reader needs is not the guide's target; it is the one on the frame in their hand.

Measure the front you already own

The frame size calculator takes the stamp and your pupil distance and returns the per-eye decentration, the verdict against the published ceilings and the widest lens a stocked blank still covers. Open the frame size calculator ↓

The measurement takes about two minutes and needs one ruler. It is worth doing before any chart, because it produces the one number every other calculation is indexed to.

• Lay the frame front flat and measure straight across it, from the outermost point of one end piece to the outermost point of the other. Do not add the lens width to the bridge; that sum is the frame's pupillary distance, not its total width.
• Read the stamp inside one temple. It is lens width, bridge width and temple length, usually separated by a square and a dash: 54 □ 18 - 145.
• Double the lens width and add the bridge. Subtract that from the total width. The remainder is the frame's end-piece allowance, both sides together, the number section four showed to be the least stable in the record.
• Measure the depth of the opening vertically at its tallest point. Compare it with the ceiling for your outline in Table 2, not with the lens width.
• Put your pupil distance from the prescription beside the frame's own: frame PD minus your PD, halved, is the per-eye decentration. Five millimetres per eye is the published ceiling; three is the tighter target this site uses.

Eleven dated numbers, and what each was attached to

Table 3 orders eleven published positions by date, from January 2019 to September 2026, with the undated one last. The third column is the number each source printed. The fourth is the part of the world that number was indexed to: a sex, a pupil, a lens blank, a material, a face width, a frame, or an outline.

Only one row attaches a millimetre to a face outline, and it does so for one outline and one dimension: a July 2026 fitting page puts a round face's lens depth under about 40 mm. Every other millimetre in the table is attached to something else. That is the finding the table exists to show. The shape advice in the fourth column is not absent; it is present in words, and it is not carrying a number.

The table also shows how the record behaves. The three stamped bands hold for seven years and eight months. The pupil range widens. The end-piece allowance is rewritten within five weeks. Laboratory numbers reach consumer pages only in the last ten months of the window. What did not happen in the window is a per-outline row for lens width, bridge or temple.

One position per row, in publication-date order; the undated row is last because there is nothing to sort it by. The third column is what each source published as a number, not this page's estimate; where a source gave a worked example, the example is reproduced. The fourth column is this page's reading of what the number was indexed to. Row ten's page was read twice: the row carries the August 2026 publication, and a September 2026 re-read returned 15, 14, 14 and 12 mm over different samples. Only row nine attaches a millimetre to an outline. Where a source carried an update date but no publication date, the row says so. Inches are the millimetre value divided by 25.4.

What changed, what did not

Three things held. Lens width 40 to 60 mm, bridge 14 to 24 mm and temple 120 to 150 mm were published in January 2019; the same page still carried them at its April 2026 update, and no row in Table 3 attaches a different band to an outline. The square-versus-round distinction held in the fitting numbers too: the two outlines share a 44 mm ceiling at 136 mm, and the difference between them is a jaw corner that no stamped number records.

Three things moved. The pupil range widened from 60 to 65 mm in August 2025 to 50 to 70 mm, average 63, in April 2026. The end-piece allowance was rewritten from assumption to measurement, then rewritten again within five weeks. And laboratory constraints entered consumer pages: minimum blank size in November 2025, stock blank diameters in September 2026. Before that, a shape recommendation had nothing to be checked against.

What would change this page is narrow. A fitting source would have to publish different lens-width, bridge or temple bands for different outlines, or publish a per-outline depth ladder rather than a single ceiling. Until one does, the honest summary is the one in the first table: three stamped adult bands, one width row that is measured rather than printed, and one depth ceiling that the outline moves by 7 mm.

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