How much sunscreen is enough? The two-finger rule
The most common sunscreen mistake is not which one you bought. It is using a quarter of what the test used.
Short answer: about two finger-lengths of product for face and neck, fifteen minutes before you go out, again every two to three hours.
Where the rule comes from
SPF is measured under ISO 24444 at a fixed thickness: 2 mg of product per square centimetre of skin. Everything the number claims is claimed at that thickness. Squeeze less and the protection falls away faster than most people expect — and application studies routinely find people using roughly a quarter of the tested amount.
The two-finger measure is simply a way of getting to that thickness without weighing anything: a line of product along the length of your index finger and another along your middle finger, for face and neck together.
Timing
Apply about fifteen minutes before sun exposure so the film has settled. Reapply every two to three hours through the day, and immediately after swimming, sweating or towel drying — towelling removes product mechanically, whatever the label says about water resistance.
The bits everyone misses
- Ears, and the rim of the ear especially.
- The back and sides of the neck.
- The hairline and any parting.
- The tops of the hands, which age visibly and get the most sun of anywhere.
Comfort is a protection feature
A formula you dislike is a formula you will under-apply and skip reapplying. Texture is not vanity here — it is the difference between the protection you bought and the protection you wear. That is the argument for a light gel over something heavy, and it is why we made one product rather than a range.
More on how each batch is tested is on the proof page.
