Tools · Professional education
Spectacle to Contact Lenses
Convert spectacle power to an estimated contact lens power at a fixed vertex distance of 12 mm.
Estimated contact lens power
+0.00 D
Rounded to the nearest 0.25 D, as in the iPhone app.
About this calculation
FCL = Fspectacle / (1 − 0.012 × Fspectacle)
This converts a single optical power. It does not calculate a complete toric prescription or determine lens fit. Final contact lens selection requires an eye-care professional’s assessment.
Source cited by the GCEO iPhone app: 2020–2021 Basic and Clinical Science Course, Section 03: Clinical Optics. ISBN: 978-1681043593.
Calculations stay in your browser. No values are saved or sent to a server.