At Araya, we want our scientific methods to be transparent, but never our visors! Here is our official UV transmission report from a third party lab, Solar Light.
How UPF ratings are calculated:
1. The transmission of ultraviolet through the material is determined using a calibrated ultraviolet transmission analyser.
2. The UPF result for each measurement is calculated.
3. The separate UPF values are averaged to determine the mean UPF.
4. The standard deviation is calculated.
5. The standard error is calculated.
6. The standard error is subtracted from the mean UPF.
7. This value is rounded down to the nearest multiple of five to determine the reported UPF rating. The UPF rating also determines the Protection Category assigned to the material.
UPF rating - rounding down: The calculated UPF value (or lowest measured value) is rounded down to the nearest multiple of five to give the reported UPF rating. One effect of this is that materials actually need to achieve a calculated UPF value of 55 or higher in order to be classified as UPF 50.
For the Good UV-protection category to be stated on the label, the UPF value must lie between 15 and 24
For the Very Good UV-protection category to be stated on the label, the UPF value must be between 25 and 39
For the Excellent UV-protection category to be stated on the label, the UPF value must be 40 or greater.