How to Measure Your Glasses Frames Before Buying Online

The single biggest hesitation people have about buying glasses online is fit. You cannot try them on, the photographs all look the same size, and a frame that looks generous on a model might sit halfway across your temples in real life. It is a fair concern, and it has a straightforward answer.

Your current glasses already know your size. Almost every frame carries its measurements printed on the inside of one of the arms, and once you can read those numbers you can size almost any pair online with confidence. Here is how to find them and what to do with them.

What you will need

• A pair of glasses or sunglasses that already fit you reasonably well
• Good light, since the printing is small
• A millimetre ruler, only if your frames carry no markings

Step 1: Find the numbers on your frames

Open your glasses and look along the inside of either arm, the part that runs towards your ear. On most frames you will find a short sequence of digits, often near the hinge or towards the end of the arm. Some manufacturers print them on the inside of the bridge instead, the section that crosses your nose.

You are looking for something in the order of 52 18 140. The numbers are separated either by a small square symbol, a dash, or simply a space.

Step 2: Understand what each number means

The sequence follows the same order on virtually every frame made.

1. Lens width. The horizontal width of one lens at its widest point, usually between 40 and 60 millimetres. This is the number that most affects whether a frame looks proportionate on your face.
2. Bridge width. The gap between the two lenses, typically 14 to 24 millimetres. This determines how the frame sits on your nose, and getting it wrong is what causes glasses to slide or to pinch.
3. Temple length. The length of the arm from hinge to tip, commonly 135 to 150 millimetres. This decides whether the frame reaches your ear comfortably or grips the sides of your head.

You may also see a fourth figure, and some frames print the lens height as well. Lens height matters more for multifocal wearers, since a shallow lens leaves less room for the reading portion.

Step 3: Measure manually if the numbers are missing

Older frames, and some fashion frames, carry no printing at all. You can get close enough with a ruler.

• For lens width, measure straight across one lens at its widest point, from the inner edge of the frame to the outer edge.
• For bridge width, measure the gap between the two lenses at the narrowest point.
• For temple length, run the ruler along the arm, following the curve down to the tip as best you can.

Round to the nearest millimetre. A millimetre either way will not change how a frame feels, but ten will.

Step 4: Compare against the frames you are considering

Every frame in our range lists its measurements in the product details. Put your numbers alongside them and look for a close match rather than an exact one.

As a working rule, staying within two millimetres of your lens width and bridge width will feel familiar. Temple length has more tolerance, since the arms can usually be adjusted slightly, and around five millimetres either way is generally fine.

What to do if you are between sizes

If a frame you like sits a millimetre or two outside your usual numbers, the shape matters as much as the measurement. A slightly wider lens on a thin metal frame will feel less noticeable than the same increase on a heavy acetate one.

If your current glasses have never fitted quite right, this is also the moment to correct it rather than to copy the problem. Frames that slide down your nose are usually a bridge that is too wide. Frames that leave marks behind your ears are usually arms that are too short. Frames that feel tight at the sides point to a lens width that is too narrow for your face.

A note on prescription and fit

Fit and prescription are separate things, and both need to be right. Your prescription may also include a pupillary distance measurement, which describes the distance between the centres of your pupils and is used to position the optical centre of each lens correctly. Not every prescription includes it, so ask your optometrist if yours does not.

Every order placed with us is reviewed by a qualified Australian optometrist or optical dispenser before it is dispatched, which is a check on the prescription rather than a check on the fit. Sizing is the