Make the most
of your sun.

Solar position, the spectrum arriving now, and the dose it carries. Computed on your device, from published physics, with the radios off.

Android & iOS — coming soon
7 mintoward the vitamin D dose
21 minto the burn threshold
~50%of the ultraviolet still reaches you in open shade

Times are worked for Fitzpatrick type II at UV index 8. Yours depend on skin type, altitude, cloud, ground surface and how much skin is uncovered. The app shows the equation behind every figure and the source it came from.

Today screen: the sun's arc over the mountains, UV index 7.3, vitamin D dose, safe limit and burn threshold Sunbathe timer running: safe sun used, vitamin D produced, and the photons received by wavelength band Plan your day: morning and afternoon vitamin D windows, and the peak ultraviolet hours to be careful in The log: sessions, streaks and totals, stored on the device Night screen: stars over the ridge and a countdown to dawn