SPF tests sunburn, and water-resistant tests wet use. What closes the UVA gap?

Answer: Broad-spectrum protection

SPF 50+ number — A higher SPF number mostly strengthens the burn-protection side of the label. FDA guidance says SPF is primarily an indicator of UVB protection because it comes from a sunburn test. That still leaves a separate question: does the formula cover UVA too? The number can be high while the coverage-width word is still the thing to check.

Water-resistant claim — Water resistance answers a different question: whether the sunscreen film keeps working during wet use. It does not by itself say whether the product covers UVA as well as UVB. That matters because UVA is less tied to immediate redness, so a burn-focused number can miss part of the story. A sunscreen can be useful in water and still need the broad-spectrum label for coverage width.

Broad-spectrum protection ✓ — Right: broad spectrum is the label phrase that means coverage includes both UVA and UVB. SPF is primarily an indicator of UVB protection because the test is based on sunburn, where UVB dominates. UVA matters for skin aging and also contributes to skin cancer risk, so the label separates 'how high is the SPF?' from 'how wide is the coverage?' That split is easy to miss on a crowded bottle.