What length of a single lens should you account for the bevel?

• A. 0.5 mm
• B. 1.5 mm
• C. 1 mm
• D. 2 mm

Answer: (C)

Bevel allowance around the lens edge is the extra material you factor in so the lens can be edged and seated smoothly in the frame. For a standard single lens, about 1 mm should be accounted for this edge bevel. This provides a clean, finished edge and enough clearance to fit into most frames without removing too much material. A smaller bevel, like 0.5 mm, risks an inadequate edge finish or seating, while larger bevels such as 1.5 or 2 mm can interfere with frame fit or weaken the edge. So, 1 mm is the appropriate length to account for the bevel.