From http://nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html a lot more detail there
25 microgram = 1000 IU Assuming every other day exposure (so actually 2,000 IU every second day)
Baseline = August, grass, pale Caucasian, cloudless, 45 degrees latitude; hands+ face + arms exposed, every other day.
- Time to get an average of 1000 IU, but in the sun every second day = 4 minutes
| Change just one variable | Minutes |
| If Latitude 30 degrees* | 2 |
| If Latitude 60 degrees* | 7 |
| If Fall (Nov 1) | 25 |
| If Winter (Feb 1)** | 35 |
| If High Altitude (2.2 KM) | 3 |
| If Dark Skin (Middle Eastern) | 11 |
| If Overcast | 19 |
| If older than 70 | 12 |
| If in bathing suit (75% of skin exposed)*** | 1.3 |
Skin percentages: Face 3.5%, neck 2%, trunk 26%, hands 6%, arms 14%, legs 14%, thighs 18%.
Concerning hands - unsure if the palms generate any vitamin D since palms generally do not tan
Latitudes
30 degrees Florida, Cairo, Chongquing, Perth
45 degrees Seattle, Ottawa, Paris, Harbin, Tasmania
60 degrees Anchorage, Scotland, Oslo, Moscow
- Ignores the possibility of 'vitamin D winter' = too low intensity to make any vitamin D
See also VitaminDWiki
- Time in sun (in Spain) to get 4,000 IU of vitamin D: half hour in July , 2 hours in October – Sept 2016
- No – 30 minutes per week in sun is NOT enough – May 2011 which includes the following chart