SPF Lies? BASF calculator VS. the label

I understand that as a simulator, it won’t be 100% accurate. But the SPF being a whole 30 points lower seems too extreme to just attribute to inaccuracy. If the BASF calculator is so terribly wrong all the time is it even worth using?

Thanks for the point about the ingredients in the emulsion effecting the SPF, I didn’t know that
I do know that Vitamin C with Vitamin E can also have UV blocking properties, but very negligible. Coconut oil for example only blocks 20% of rays (Pharmacogn Review), with an SPF of around 7 (Pharmacogn Research).

But are the ingredients in the emulsion so effective that they can boost the SPF by a whole 30 points? If so, you would think such potent UV blockers would be considered active sunscreen ingredients!

But it’s not just Anthelios, I was curious about how the BASF would rate other sunscreens. I found that the label is consistently higher for almost all sunscreens.

Badger SPF35 Sport Sunscreen Cream is rated as SPF10 and PPD 11 by BASF.
It only contains: sunflower oil, beeswax, jojoba oil and tocopherol (vitamin E), plus the 22.5% zinc oxide active ingredient.
Badger SPF30 Unscented Sunscreen Cream is rated as SPF 10 and PPD 9 by BASF.
It only contains: sunflower oil, beeswax, tocopherol and seabuckthorn extract, plus 18.75% zinc oxide.

Both of these sunscreens have sunflower oil as the main emollient, so I tried doing some research as to whether the sunflower oil could be providing all of the additional SPF protection.
I couldn’t find anything that told be the SPF of sunflower oil, the closest is this table from a study that concludes the SPF of non-volatile oils are between 2-8, and between 1-7 for volatile oils. In this study a 1% v/v solution of oil, water, and ethanol was used. I guess the SPF would increase as the concentration does, so maybe because the sunscreen has sunflower oil as the carrier it does provide quite a bit of SPF protection. I’m doubtful though.

Curiously enough, I found a sunscreen that contains less zinc oxide but is rated as higher SPF. Thinksport SPF50+ Sunscreen only contains 20% zinc oxide yet is higher than Badger Sunscreen. Even weirder, Thinksport has two products both with 20% zinc oxide and almost the same ingredients, but different SPF!

Thinksport SPF25 Every Day Sunscreen: WATER, ALOE BARBADENSIS LEAF JUICE, CAPRIC CAPRYLIC
TRIGLYCERIDES, SORBITAN STEARATE, PINE WOOD RESIN, VEGETABLE GLYCERIN, CETYL DIMETHICONE, HYDROGENATED CASTOR
OIL, MAGNESIUM SULFATE, SUNFLOWER OIL, JOJOBA OIL, ASCORBIC ACID, TOCOPHEROLS, OLIVE
OIL, RASPBERRY SEED OIL, CRANBERRY SEED OIL, HYALURONIC ACID, CURRANT, CITRUS PARADISI, IRON OXIDE.

Thinksport SPF50+ Sunscreen: WATER, ALOE BARBADENSIS LEAF JUICE, CAPRIC CAPRYLIC
TRIGLYCERIDES, SORBITAN STEARATE, PINE WOOD RESIN, VEGETABLE GLYCERIN, CETYL DIMETHICONE, HYDROGENATED CASTOR
OIL, MAGNESIUM SULFATE, SUNFLOWER OIL, JOJOBA OIL, ASCORBIC ACID, TOCOPHEROLS, OLIVE
OIL, RASPBERRY SEED OIL, CRANBERRY SEED OIL, HYALURONIC ACID, GLUCOSE & GLUCOSE OXIDASE AND LACTOPEROXIDASE, CURRANT GRAPEFRUIT.  

I really don’t understand how some trace amounts of glucose oxidase and iron oxide can mean the difference between SPF 25 and 50.