Health & Medical

Contact Lens Vertex Calculator

Convert spectacle prescriptions to contact lens powers by adjusting for vertex distance.

Spectacle Rx

Lens Power (Diopters)

Sphere (SPH)

Cylinder (CYL)

Parameters

Vertex (mm)

Axis (deg)

Standard vertex distance is usually 12mm - 14mm.

Calculated Power

-0.00 Sph

-0.00 Cyl

180 Ax

Effective Change: 0.00 D

No significant change required.

Glasses -5.00

Contacts -4.71

Vertex Formula

F_CL =

F_Glasses 1 - (d × F_Glasses)

Note: Powers under 4.00D typically don't need vertex adjustment. Consult an optometrist.