Testing the best way to measure #sunscreen using the #twofingerrule VS the quarter teaspoon method. Spoiler Alert. Both are identical PROVIDING you do proper thick lines. I see far too many people promoting the 2-finger rule for sunscreen who use either very thin or broken lines of product. Less product = Less protection. Simple. Done correctly 1 finger length is roughly a quarter teaspoon, so 2 fingers equally roughly half a teaspoon. The amount needed for full face & neck application.