Convert a lens surface between radius, tooling power, true surface power and sag. Enter any one value with the material and diameter, and the calculator fills in the rest.
Labs describe the same curve in different ways depending on the equipment. This calculator converts between them for any lens material.
- Radius of curvature (mm): a shorter radius means a steeper curve and more power.
- 1.530 surface power: the tooling reference most lab tools and lens clocks use.
- Actual surface power (D): the real power of that curve in the chosen material, such as CR-39, polycarbonate or high index.
- Sagitta (mm): the depth of the curve across the chosen diameter. It's key for thickness and for making sure a lens fits the eyewire without bulging.
Use it during surfacing and quality checks to confirm tool curves and true power.
