Millimeters can be tricky to visualize! Use this converter to figure it out. 8mm converts to about 0.31 inches, which is roughly 5/16 of an inch. To give you a better sense: that's about the thickness of two stacked quarters, or slightly thicker than a pencil. For a phone case, 8mm is actually pretty substantial - it would provide good protection but definitely adds noticeable bulk to your phone. Most slim cases are around 1-2mm, standard protective cases are 3-5mm, and heavy-duty cases are 6mm or more. At 8mm, you're definitely in the "rugged protection" category. Your phone is going to feel noticeably chunkier in your hand and pocket. If you want a protective case, that's great! But if you're going for sleek and minimal, 8mm might be too bulky for your taste. For reference: a credit card is about 0.76mm thick, a dime is 1.35mm, and a US quarter is 1.75mm. So 8mm is roughly 4-5 quarters stacked. That helps put it in perspective! I'd suggest checking reviews with photos to see how it looks on actual phones before committing.