About UV Balance
Sun-exposure literacy for everyone — backed by peer-reviewed science, not medical opinions.
Our mission
Sunlight is neither purely beneficial nor purely harmful — the dose and context determine the outcome. UV Balance exists to give people the quantitative tools they need to make genuinely informed decisions about sun exposure: how long is safe for their skin type, how much vitamin D a session might yield, and how UV Index — not temperature — is the only number that matters for both burn risk and photosynthesis of vitamin D₃.
Most public guidance on sun safety collapses into two competing extremes: "avoid the sun entirely" or "get as much as possible." Neither serves the millions of people who are simultaneously at risk of vitamin D deficiency and photoaging or skin cancer. UV Balance is built on the conviction that the middle path — calculated, time-limited, deliberate exposure — is both safer and healthier than either extreme, and that the science to navigate it should be freely accessible to everyone, not locked behind a clinical consultation.
How the calculations work
UV Balance fetches real-time UV Index data from Open-Meteo, an open-source weather API that aggregates satellite and ground-station data. All burn-time and vitamin D estimates follow the WHO Global Solar UV Index Guide and the skin-dose models published by Holick (2004) and Webb & Engelsen (2006). The full reference list is in the footer of every page.
Key inputs are UV Index, Fitzpatrick skin phototype, exposed body-surface area (BSA), and session duration. The app calculates your estimated Standard Erythema Dose (SED) exposure and maps it against your skin type's Minimal Erythema Dose (MED) to produce a burn-risk estimate and a vitamin D₃ production estimate in IU. Both figures carry meaningful uncertainty — real-world UV exposure varies with cloud cover, altitude, reflective surfaces (snow, water, sand), prior tan, topical sunscreen, and individual biology. The tool shows this uncertainty explicitly rather than hiding it behind false precision.
Who built this
UV Balance was created by an enthusiast of sun, tanning and vitamin D. UV Balance is an independent project with no affiliation to any pharmaceutical company, sunscreen brand, or supplement manufacturer. Product links on the site are affiliate links that help cover server costs; they are clearly labelled. We do not use advertising networks or sell user data — see our Privacy Policy for details.
UV Balance is an independent project with no affiliation to any pharmaceutical company, sunscreen brand, or supplement manufacturer. Product links on the site are Amazon affiliate links that help cover server costs; they are clearly labelled. We do not use advertising networks or sell user data — see our Privacy Policy for details.
Contact
For questions about the science behind UV Balance, to report a calculation error, or for press enquiries, email:
We aim to respond within 3–5 business days. We are unable to provide individual medical advice by email — please consult your physician or dermatologist for personal health questions.