Oval / Oblong Boundary Chart

The lines to put the tape on, all four published borders on one number line with the shared ground shaded, the denominator switch worked both ways, what each border means in centimetres for your own width, a centimetre-and-inch strip, and a two-method log. Four pages on A4, print it or keep it on your phone.

1. The lines to put the tape on

• 1 Face lengthCentre of the hairline to the tip of the chin, hair pushed fully back. cm  =   in
• 2 Cheekbone widthAcross the tops of the cheekbones, point to point. This is the denominator two of the three published borders use. cm  =   in
• 3 Jaw widthCorner to corner at the angle of the jaw, not around the chin. cm  =   in
• Forehead widthAt its widest. Used only to see whether the three widths step down or run level. cm  =   in

Convert with inches = centimetres / 2.54. One inch has been exactly 25.4 mm since 1959, so the division is exact arithmetic rather than an approximation, and a ratio is unchanged by it either way. Section 4 has both directions worked out.

2. The four borders, on one number line

The two bars are this site's rule set on the tape scale, each its centre plus or minus 0.18: oval 1.27 - 1.63, oblong 1.47 - 1.83. The darker block where they overlap, 1.47 - 1.63, is the shared ground - a ratio landing there is being labelled by choice of convention rather than by measurement. The four dashed markers are the published borders, and they are not the same thing as the bars: three of them are single numbers from guides, the fourth is this site's centre.

Four borders currently in print, and what one face reads as under each. The face is 22 cm long with widths of 14 cm forehead, 15 cm cheekbones and 13 cm jaw - the worked example printed by the guide that draws the 1.5 border. Each row uses that row's own denominator, which is the whole point.

Oblong starts at	Published	Divides length by	The 22 cm face reads as
1.5	16 July 2026	average of the three widths, here (14 + 15 + 13) / 3 = 14	22 / 14 = 1.57, oblong. Its own 1.45 - 1.5 band, the long oval, sits below that.
1.6	22 November 2025	cheekbone width, here 15	22 / 15 = 1.47, oval
1.75	14 August 2026	cheekbone width, here 15	22 / 15 = 1.47, oval, with the guide itself stating there is no hard cutoff
1.65	12 September 2026, this site	cheekbone width, on the tape scale	22 / 15 = 1.47, oval: 0.11 standard deviations above the oval centre and 1.00 below the oblong one

One face, one tape, no arithmetic error anywhere, and four verdicts. Divide the same face by the average width instead of the cheekbone width and the ratio is 1.57, which on this site's rule set is 0.67 standard deviations above the oval centre and 0.44 below the oblong one - inside both bands at once, which is the case where the result page names a second shape rather than picking one. Every figure of that kind on this sheet is (your ratio - the centre) / 0.18, against this site's two centres, oval 1.45 and oblong 1.65, and the 0.18 tolerance that goes with both. The 1.65 border is this site's own number, published with its tolerance and its method at /about; it is not a fourth guide's.

3. The denominator switch, worked both ways

Forwards, on the printed example. A face 22 cm long, widths 14 / 15 / 13 cm.

Backwards, from a border to a length in your own unit. Multiply your cheekbone width by the border you have chosen and you get the face length at which that border starts calling you oblong - no ratio to compute, nothing to divide.

The face length at which each of the four borders calls you oblong, for cheekbone widths from 12 cm to 16 cm. Find your width in the first column and read across; in inches, divide the length by 2.54 or use section 4.

Cheekbone width	At 1.5	At 1.6	At 1.65	At 1.75
12.0 cm / 4.72 in	18.00	19.20	19.80	21.00
12.5 cm / 4.92 in	18.75	20.00	20.63	21.88
13.0 cm / 5.12 in	19.50	20.80	21.45	22.75
13.5 cm / 5.31 in	20.25	21.60	22.28	23.63
14.0 cm / 5.51 in	21.00	22.40	23.10	24.50
14.5 cm / 5.71 in	21.75	23.20	23.93	25.38
15.0 cm / 5.91 in	22.50	24.00	24.75	26.25
15.5 cm / 6.10 in	23.25	24.80	25.58	27.13
16.0 cm / 6.30 in	24.00	25.60	26.40	28.00

Lengths in centimetres, rounded half up to two decimals. Holding an inch tape instead? The same multiplication works: at a 5.5 in cheekbone width the 1.6 border starts at 8.80 in of length. Read the spread in any one row before you read your own number - the four borders disagree by 3.50 cm of face length at a 14 cm width, which is more than the distance between two careful measurements of the same face.

Your own face, both ways. Fill it in and compare the two ratios; the gap between them is what the choice of denominator is worth on you.

• Face lengthCentre of hairline to chin tip.
• Average of the three widths(forehead + cheekbones + jaw) / 3.
• Ratio by the averageLength / average. The denominator the 1.5 border uses.
• Ratio by the cheekbonesLength / cheekbone width. The denominator the 1.6, 1.75 and 1.65 borders use.
• The gap between themSubtract. Anything over 0.05 is enough to move you across a border.

4. Centimetres and inches

Converting cannot move you across a border, because a ratio is one length over another in the same unit and the unit cancels. Worked on the 22 cm face: 22 / 14 = 1.57, and in inches 8.66 / 5.51 = 1.57. What moves you across a border is changing the denominator, not changing the unit.

5. Two-method log

Method A is the tape. Method B is the mirror, hair pulled back, lens or eye at eye level: the side line and the three widths, which need no arithmetic. Fill in both before you look at either verdict - the reason to keep both is that they answer different questions, and in the shared ground only one of them is about your face.

The order is the argument: side line first, ratio last, and the ratio only ever against one border you have named.

Step	A: tape	B: mirror	Do they agree?
Side line, temple to jaw corner		straight / curving in
The three widths: step down or run level
Jaw / cheekbone ratio
Length / cheekbone ratio, denominator written down
Border chosen by name: 1.5 / 1.6 / 1.75 / 1.65
Verdict under that one border
Second reading, tape moved 2 mm on the length
What you will change, keyed to the dimension not the word

The second reading row is not padding. Two millimetres on a 22 cm length moves 1.57 to 1.59, which is two places in the second decimal of a number whose published borders are stated to two decimals. If your two readings straddle a border, you are inside the shared ground and the border is not the instrument that settles it. If they do not, take the second reading as your number and write the date beside it.