At WeeFizz, measurement is our core skill. For workwear, a few answers are enough to recommend the right size, with no photo. We are now extending this expertise to equipment where a few millimetres change everything: safety glasses. Here, the reference cannot come from a size chart. It comes from measuring the face, using the camera. The method is being tested at WeeFizz, on a real range of frames.
Why the size of safety glasses matters
The same range of glasses often comes in several widths that look alike in a catalogue photo. Nothing on a product page tells a buyer which one is theirs, and they sometimes order for dozens of people they have never measured.
- A frame that is too wide slips and lets particles in from the sides.
- A frame that is too narrow presses on the temples and ends up pushed onto the forehead.
- In both cases, the equipment is worn, but it no longer protects as it should.
A photo has no scale: the iris provides one
In a photo, nothing tells you whether a face is large or simply close to the lens. To measure, you need an object of known size in the image. On a face, there is one: the iris, the coloured disc around the pupil. In adults its diameter is 11.7 mm, with very little variation from one person to another. It is our ruler: the radius of each iris gives the number of millimetres per pixel, and therefore the real size of the face.
This sets one condition: the eyes must be sharp and clearly visible. If the iris is too small in the image, the tool refuses to measure rather than return a wrong figure.
The measurement chain, step by step
The wearer faces the camera of their phone or computer. An oval guides the framing and the photo is taken automatically once everything is in place. The measurement then goes through five steps. Each one can refuse, none of them guesses.
- Detection: 478 landmarks are placed on the face, irises included, always on the full-resolution image.
- Scale: the average radius of each iris gives the millimetres per pixel. If the two eyes differ too much, the measurement is refused.
- Pose: head angles are checked. Beyond the tolerances, the measurement is refused.
- Burst: five images are taken in quick succession and measured, and the median is kept.
- Plausibility: a result outside the range of an adult face points to a wrong scale, and no figure is shown.
The output is four measurements in real millimetres: face width, face height, pupillary distance and nose width. It all takes less than a minute, with no app to install.
From face measurement to the right frame
Face width is compared with the overall widths published by the manufacturer for each frame, not with an S, M or L label. The rule is simple: a frame must not be narrower than the face. The tool selects the closest-fitting frame that meets this rule, and shows the resulting clearance in millimetres along with the reason for the choice. It is the same principle as for our workwear size charts: the person's measurements against the product's real dimensions.
Size comes from the face, the model comes from the job
Knowing your size does not tell you which frame to choose. A welder, an order picker and a quality inspector can have the same face and very different needs. So we separate the two decisions:
- the workplace decides the lens tint;
- the main risk decides the fit: temples, elastic strap or the lightest frame;
- constraints rule out certain models: prescription glasses, helmet, respirator, work at height.
The final screen shows the selected frame, its reasons in plain language, two alternatives and what was ruled out. These matches do not replace the employer's risk assessment, and the screen says so.
Photo and privacy
For glasses, measuring the face requires an image, unlike our workwear size recommendations, which use none. The photo is not stored: it only exists for the duration of the session, in the browser. The wearer can also see the frame on their own face with virtual try-on.
What we are still validating
The accuracy stated today is plus or minus 5 mm. The main source is not the calculation: it is the natural variation of iris diameter between people. The next step is validation on real faces, measured with a calliper alongside the tool. Missing data is reported as missing: the tool never makes it up.
Our measurement expertise, from garments to glasses
Size recommendation for workwear, allocation campaigns with WeeFizz PRO, and now face measurement for safety glasses: the question stays the same, which exact reference for this person? PPE manufacturers and distributors who want to test the method on their own frames can get in touch.
Frequently asked questions
How do you find your safety glasses size?
By measuring the width of your face and comparing it with the overall width of the frames. The method tested by WeeFizz measures the face to the millimetre with a phone or computer camera, then selects the closest-fitting frame that is not narrower than the face.
How can you measure a face from a simple photo?
You need a reference of known size in the image. WeeFizz uses the iris, whose diameter in adults is 11.7 mm with very little variation. It acts as a ruler to convert pixels into millimetres.
How accurate is camera-based face measurement?
The stated accuracy is plus or minus 5 mm, mainly due to the natural variation of iris diameter. Validation with a calliper on real faces is the next step.
Is the photo of the face stored?
No. The photo only exists for the duration of the session, in the browser, and is not stored.
Do you make or distribute safety glasses?
Let's test the method on your own frames and technical data sheets.
Write to us →
