Measuring eyeglasses size starts with the pair you already wear. Those little numbers on the inner arm describe its fit, and matching them is the easiest way to order frames that fit the first time.
Poor sizing shows up as small indents on the sides of your nose or an ache behind your ears. This guide explains each number, how to measure without them, and which quick checks confirm comfort.
Eyeglass Frame Measurements And Sizing Numbers
Look inside of the temple to find a sequence of 3 numbers like 52 18 135, sometimes with a small rectangle between the first two. All three are measured in millimetres, each describing one part.
Lens Width
The first number is lens width, or eye size, measured at the widest point. Most fall within 40 mm to 60 mm; 50 mm or less reads small, while wider than 55 mm reads large.
Bridge Width
The middle number is bridge width, the gap above your nose, usually 14 mm to 24 mm. Too tight and frames pinch your nose; too loose and they slide. Close-set eyes suit a narrow bridge.
Temple Length
The last number is temple length, measured from the hinge to the temple tip. Most sit at 135 mm, 140 mm, 145 mm or 150 mm, and should rest along the sides of your head.
Lens Height
Some frames show a fourth number, the lens height, measured at the tallest parts of the lens. It rarely matters for single vision, but it decides whether bifocal segments and reading zones actually fit comfortably.
Progressive lenses need the most depth, because a shallow lens squeezes the corridor and crops reading power. Shoppers moving into multifocals should favour deeper frames and check the frame size and fit guide before choosing.
How To Measure Glasses And Face Width At Home
Measuring at home needs only a measuring tape or ruler, a mirror and a few minutes. The checks below cover frames with missing numbers and the face measurement that shows which total width feels comfortable.
Unmarked Frames
Older frames often lose their numbers. Lay the glasses on a level surface, then use a metric ruler to measure each lens from inner rim to outer edge of the lens, plus the bridge gap.
For temples, measure to the bend first, then add the length of the drop for the total temple length. Arms can stay open or closed, and opticians use this exact millimetre method when checking frames.
Total Frame Width
Total frame width is not printed, but estimating is easy: add lens width twice to the bridge, so 52, 52 and 18 give roughly 122 mm. Including hinges and design features pushes it slightly wider.
To size the face, stand in front of a mirror with a ruler in line with your temple and note the distance between your temples. Frames within +/- 3mm of that figure fit most comfortably.
Glasses Fit Guide For Nose, Brow, Temples And Ears
Numbers get the size close, but the face gives the final verdict. A few quick mirror checks, done within the first hour of wear, reveal whether the frame needs adjusting, exchanging or some breaking in.
Nose and Brow
The top rim should sit no higher than the line of your eyebrows, with eyes centered in each lens. Seeing no red marks after an hour confirms the bridge design and position suit the nose.
Temples and Cheeks
Frames shouldn’t be wider than the width of your face at the temples, and the lower edge must clear the cheeks to avoid rubbing. Arms should fit horizontally, curving around the outside of your ear.
Face Size Ranges
Across the front, as a rough rule, small or narrow faces suit total frame widths less than 129 mm, medium size faces wear 130 mm to 139 mm, and wider faces go over 139 mm.
Brand Differences and Returns
Sizing varies between different models, so a little trial and error is normal. Buy where a clear return policy exists, and small fit issues often need only minor adjustments, explained in this frame adjustment guide.
Finding The Right Eyeglasses Size And Frame Fit
Good fit comes down to three numbers, one face measurement and a quick mirror check. Get those right and new glasses distribute pressure evenly across nose, head width and ears, so they disappear all day.
For a step-by-step reference, the how to measure frame size page keeps everything in one place. Then browse eyeglasses collection by size, comparing measurements on product pages against the numbers already saved from a favourite pair.
Frequently Asked Questions
Where Else Can Frame Measurements Be Found?
Besides the arm, numbers appear on the back of the bridge or the nose piece, written with dashes like 48-19-140. If nothing is printed inside of your glasses, the retailer’s product listing usually shows them.
Which Frame Size Suits a Small or Petite Face?
A small face looks best in smaller glasses frames kept in proportion, with lens widths around 48 mm or below. Brands group these within a family of sizes labelled XS or S, especially in petite ranges.
What If the Arms Feel Too Short or Too Long?
Arms should sit comfortably over your ears without pressing. Most range from 120 mm to 150 mm, and the tip of the arm can be reshaped, though frames with straight sides rely on correct length.
Do Sunglasses Use the Same Sizing?
Yes, the same three-number system applies, though sunglasses often run wider for extra coverage. Comparing lens width and bridge against a trusted favourite pair works just as well for prescription sunglasses as for everyday eyeglasses.
Is Frame Size the Same as PD?
No. Frame size describes the glasses, while pupillary distance measures the gap between pupils for accurate lens centring. Both matter equally when ordering online, so always use this PD measuring guide alongside the frame numbers.