FREE TOOL · ON DEVICE · NO MILLIMETRE SCALE
Pupillary distance: the ratio a photo can give you, and the millimetres it cannot
This tool compares the spacing between two detected iris centres with the width of your face. The photo stays in your browser. The result is a ratio, never an eyewear measurement.
LOCAL MEASUREMENT · NO MILLIMETRES
Read this first if you need PD for glasses
Glasses orders need pupillary distance in millimetres. A photo without a known-size object cannot convert pixels into millimetres. This ratio is not suitable for ordering lenses or any clinical decision.
How the ratio is calculated
The detector provides two iris centre landmarks. After straightening the face, we divide their distance by face width in the same image. Both values use the same pixel scale, so the units cancel out.
Why there is no reference band yet
The current reference mesh does not include the two iris centre points used by this tool. Without a comparable front-view reference measurement, printing an “ideal” value or ±5% band would be misleading. Your own ratio is shown without a beauty label or population ranking.
Privacy and limits
The photo, landmarks and ratio are processed locally and are not uploaded or stored on FaceGrader servers. A clear front view is needed; reflections, partly obscured eyes, head pose and image quality can affect detected points.
Questions about this measurement
Can this give me pupillary distance in millimetres?
No. A single photo has no physical scale. For an eyewear order, get a millimetre measurement from an optician or a method with a known-size reference.
What does this ratio mean?
It divides the distance between the two detected iris centres by face width in the same photo. It is a dimensionless geometric proportion.
Does this change my 0–100 FaceGrader score?
No. The composite score uses symmetry, facial thirds, facial fifths and golden ratio. This pupil spacing ratio is independent.
Will my photo or ratio be sent to FaceGrader?
No. This single-purpose tool processes the photo and displays its ratio in your browser. It creates no server result record.
Will the same photo give the same ratio?
The formula uses fixed iris landmarks and face-width coordinates. On the same device and engine version, the same image file returns the same displayed ratio. Different photos or browser environments can move detected points.
Why was my photo rejected?
The same quality gates as the main scan reject images with no face, multiple faces, a small face, excessive head tilt, a turned head or unreliable geometry. Rejected photos receive no ratio.