Mineral vs Chemical Sunscreen: The Honest Comparison
No tribalism, just what each type actually does well.
Sunscreens are tested at 2 mg/cm²; most people apply only 0.5-1.0 mg/cm².
Lab Muffin's Michelle Wong notes most people apply only a quarter to half the tested amount of sunscreen.
Frequently asked questions
How often do I need to reapply sunscreen?
Reapply about every two hours of sun exposure, and immediately after swimming, heavy sweating or toweling off. Indoors and away from windows you generally don't need to reapply, but a single morning application also wears off — so reapply if you're near windows or heading back outside.
Is mineral or chemical sunscreen better?
Neither is universally better. Mineral (zinc/titanium) sits on the skin, is photostable and often suits sensitive skin, but can leave a white cast. Chemical filters are usually lighter and more cosmetically elegant. The best sunscreen is a broad-spectrum one you'll wear daily and apply generously.
How much sunscreen should I actually apply?
Most people apply far too little. Sunscreen is tested at 2 mg/cm², but typical use is a quarter to half that — which can drop an SPF 50 to real-world SPF 15 or lower. Aim for about a quarter to half teaspoon for the face and roughly a shot glass (1 oz) for the whole body.
r/SkincareAddiction: 'How much sunscreen is the two-finger rule actually?'
Sources & citations
- Taylor S & Diffey B, 'Simple dosage guide for suncreams,' BMJ 2002;324:1526 (PMC1123459)
- labmuffin.com ↗