I sometimes use the EO Calculator but it doesn't have a Tangerine Essential Oil listed. The IFRA from where I purchased the Tangerine Essential states for Category 9 that the maximum usage rate is 100%. Now this isn't the first time that a fragrance oil or essential oil has stated 100%. My question is since there is no maximum how do I know how much of it I can use? Maybe I'm over thinking this. The IFRA is stating that no matter how much I use it's safe on skin???? I'm going with 6% as this is my average I've used in the past.