SPF effectiveness calculator
SPF blocks (1 − 1/SPF) of UVB. SPF 30 ≈ 97%; SPF 50 ≈ 98%.
⚠ Educational estimates only — not medical advice. Consult a healthcare professional.
About this tool
SPF effectiveness calculator is a single-purpose utility on instant.tw, a free toolbox of calculators, converters, generators, and quick lookups. Everything works in your browser — nothing is uploaded, nothing is stored on a server unless explicitly noted.
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