LensFit

Understand Your
Lens Options

Compare how frame size and materials affect lens thickness. A calm, honest guide based on geometry—not sales.

Not medical adviceEstimation onlyEducational

Why this tool exists

Most optical shops focus on upselling—pushing high-index lenses when a smaller frame might work better, or ignoring how frame PD affects thickness. We believe you deserve transparent, physics-based information to make your own choices.

Frame Size > Material

Here's what they don't tell you: choosing a 4mm smaller frame can reduce edge thickness more than upgrading from 1.60 to 1.74 index.

The Hidden Factor

If your PD doesn't match the frame, you're paying for extra lens material you don't need—and getting thicker edges.

Know the Trade-offs

High-index isn't always better. 1.74 has more chromatic aberration than 1.60. Sometimes 'good enough' is actually optimal.

How it works

1

Enter your prescription

PD, sphere, and cylinder (if applicable). We'll explain what each means.

2

Add frame sizes

Compare up to 3 frames. Just need lens width and bridge—found on the temple arm.

3

See all materials

We calculate ALL material options at once—so you can see exactly where diminishing returns kick in.

4

Make an informed choice

See thickness, decentration, and trade-offs clearly. No sales pressure, just physics.

Frequently Asked Questions

Things your optician might not mention

Important Note

This tool provides geometric estimates only. It is not a medical device, does not generate prescriptions, and should not replace professional advice.