Contact Lens Power Conversion Guide | IVALens
Wearing contact lenses requires a slightly different prescription than your glasses. This page helps you understand how to convert your spectacle power into contact lens power — safely and accurately.
⚠️ Note: This tool is for general guidance only. Always confirm your lens prescription with an optometrist.
Conversion Table: Sphere (SPH) Only
📌 Use this table only if your glasses prescription includes just SPH (no CYL or AXIS)
| Glasses Prescription (SPH) | Estimated Contact Lens Power |
|---|---|
| 0.00 to -3.25 | Same as glasses |
| -3.50 | -3.25 |
| -3.75 | -3.50 |
| -4.00 | -3.75 |
| -4.25 | -4.00 |
| -4.50 | -4.25 |
| -4.75 | -4.50 |
| -5.00 | -4.75 |
| -5.25 | -5.00 |
| -5.50 | -5.25 |
| -5.75 | -5.50 |
| -6.00 | -5.75 |
| -6.25 | -6.00 |
| -6.50 | -6.25 |
| -6.75 | -6.50 |
| -7.00 | -6.75 |
| -7.25 | -7.00 |
| -7.50 | -7.25 |
| -7.75 | -7.50 |
| -8.00 | -7.75 |
⚠️ Notes:
- This table is a general guide for spherical prescriptions only (no CYL or AXIS)
- Works best for lenses worn at 13–15mm vertex distance (standard for contacts)
- For astigmatism (CYL > -0.75) or multifocal needs, a different lens type like toric lenses is needed
- Always confirm with a certified optometrist before ordering lenses.
When NOT to Use This Table
- You have Astigmatism (CYL or AXIS in your prescription)
- You need Toric Lenses
- You have Multifocal / Progressive needs
- Your power is above -8.00
