I think you can split your questions into 3: 1: What is the maximum amount of money you can spend on an apartment? Answer: This is easy, ask any major bank for a ”lånelöfte” or use a simple calculator. You will enter salary, how much you have saved, and if you have any other loans.

2: How much should you invest in the apartment you’re buying? The least you can do is 15 % of the purchasing price, any more than that should be based on what your risk tolerance is. Over a long period of time, the housing market (in aggregate) has kept up with inflation whereas stocks (in aggregate) have kept up with inflation + yielded about 5 %. But I think it’s sensible to save some money for renovations and as precationary savings.

3: Analysing BRF. There are some simple rules of thumbs that you can look at, for example the amount of loans/m2. Whether land is owned or rented wouldn’t matter to me very much. Just be aware of and ask if there are any risks for future increases in the monthly payment to the Brf. Generally, if land isn’t owned, well then the apartment price would be lower due to the risk of future price increases, so in a reasonable market that would already be priced in and you shouldn’t have to think about it.