Specs Frame Size Chart: My Simple Breakdown
When I first looked at a specs frame size chart, I was confused by all the numbers and diagrams. Here’s how I finally made sense of it all.
The Basic Three Numbers
Every pair of specs has three key measurements printed inside, like “52-18-140”:
- 52 – Lens width in millimeters
- 18 – Bridge width in millimeters
- 140 – Temple length in millimeters
Why These Numbers Matter
Each measurement affects fit differently:
- Lens width – Determines if frames look proportionate on your face
- Bridge width – Affects comfort on your nose
- Temple length – Ensures arms reach properly behind ears
How I Use Size Charts
My process is simple:
- Find specs I own that fit well
- Write down their three numbers
- Look for new specs with similar measurements
- Stay within 1-2mm of my ideal size
Common Size Ranges
Most specs fall into these categories:
- Small: 48-50mm lens width
- Medium: 51-54mm lens width
- Large: 55mm+ lens width
My Key Takeaway
Once I understood what the numbers mean, size charts became incredibly useful. They’re not complicated – just three simple measurements that ensure proper fit.



