A buyer asked for “bulletproof polycarbonate, 25 mm”. That number is not a specification. UL 752 defines eight levels, and 25 mm can satisfy Level 1 while failing Level 3 badly. The level is the spec; the thickness is the consequence.
The levels that matter commercially
- Level 1 — 9 mm handgun, two shots. Clear polycarbonate commonly 19–25 mm.
- Level 2 — .357 Magnum. Roughly 25–32 mm.
- Level 3 — .44 Magnum. Roughly 32–38 mm.
- Level 4 and above — rifle rounds; a monolithic PC sheet is no longer practical and laminated or glass-clad builds take over.
The thickness bands overlap because the panel’s performance also depends on the mounting. A sheet tested free-standing and one clamped in a steel frame do not produce the same result.
The trap: buying a thickness, not a rating
Suppliers quote “25 mm ballistic PC” because thickness is easy to compare. But UL 752 is a test protocol: the panel has to stop a specified round at a specified velocity for a specified number of shots, with no penetration and limited spall. A 25 mm sheet from a supplier without test backing may pass informally and still fail an insurance or code review.
Ask for the level, the test report reference and the test laboratory. If the answer is a thickness and a photo of a shot panel, that is not a rating.
Spall is the other half of the job
Stopping the round is only part of the requirement. On the protected side, fragments must not become projectiles. Polycarbonate is better than glass here because it deforms rather than shatters, but a thin PC sheet on a heavy round can still spall. Level 2 and above normally calls for a laminated build or an anti-spall liner on the safe side.
The level-to-thickness relationship is set out in bulletproof polycarbonate sheet UL 752, and the certified glazing case in UL 752 ballistic glazing.
Frequently Asked Questions
Q: What thickness of polycarbonate meets UL 752 Level 1?
A:Commonly 19–25 mm clear polycarbonate for the 9 mm handgun test, two shots. The exact figure depends on the mounting, so the rating should be confirmed by test report rather than taken from a thickness table.
Q: Is there a single “bulletproof” thickness?
A:No. UL 752 has eight levels from handgun to rifle, and the required thickness changes with each. A sheet that stops a 9 mm round at 25 mm will not stop a .44 Magnum at the same gauge.
Send the threat level, opening size and fixing condition to oversales@rpplexiglass.com for a rated polycarbonate panel quotation with UL 752 test backing.