Film that allows 1% UV transmission would have an SPF of 100 at 1.5% UV transmission, the SPF would be approximately 66.66 and with a UV transmission of 2%, the SPF would be 50 (Calculation must include full range of UVA and UVB radiation 290-400 nanometers*IWFA education guide). Sun protection factor numbers are officially determined according to established testing protocols. No claims can be made about actual SPF numbers without having these tests performed by a qualified laboratory.