Vitamin D and Sunbathing Time Calculator

https://fastrt.nilu.no/VitD_quartMEDandMED_v2.html

 

If you don't want to sunbathe (due to concerns about skin cancer), you could get your hands on canned cod liver. Consuming a can or two every week ought to be enough to keep your vitamin D (and A) levels where they ought to be.

This is what how Eskomos and Vikings had been able to live above the Arctic Circle and not suffer from rickets.

 

Or you can buy Vitamin D3 5,000 IU pills and pop one a day.

 

When it comes to improving health outcomes, taking vitamins and supplements in pill form is notoriously ineffective:
https://www.medscape.com/viewarticle/915337

https://www.livescience.com/65186-vitamins-minerals-food-supplements.html

 

That's why you take them with food.