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Ask HN: What Are You Working On? (June 2025)

439 points david927 | 1 comments | 29 Jun 25 20:21 UTC | HN request time: 0s | source

What are you working on? Any new ideas which you're thinking about?
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weepinbell ◴[30 Jun 25 16:57 UTC] No.44425496[source]▶
https://tinkerdeck.com/projects/rent-buy-growth

I've been basing one of the biggest financial decisions in my life - whether to buy a house - in large part on NYT/NerdWallet Rent-Buy calculators. But when I dig in, it seems that the model is both extremely sensitive to home/S&P500 growth assumptions, and that their defaults aren't well thought through.

This site is my attempt to organize my thoughts on what reasonable defaults should be, and provides an interactive tool to explore housing and S&P500 growth historical growth rates.

I'd appreciate feedback!

replies(2): >>44426427 #>>44426898 #
ashwinsundar ◴[30 Jun 25 19:23 UTC] No.44426898[source]▶

    On my own finances, plugging my "preferred" numbers into the NYTimes calculator along with a plausible house price and financing that I would buy, changes the rent/buy difference by more than $1.5M over 25 years (!!!!).
You're not doing anything wrong, you're just plugging in some more accurate knowledge about the local housing market that you have. The calculator had to use some sort of assumptions, so they seemed to have gone with medians or averages that made sense at the time.

I tried playing this game too when I bought my house. I ran Monte Carlo simulations which concluded that buying a house was a bad idea, based on historical data. Plus, this whole new "Covid" thing was surely to crash the housing market, right? I ended up buying a house anyway, and found out a little later that my projections were completely wrong. You can't predict the future, after all...

replies(1): >>44428826 #
1. weepinbell ◴[30 Jun 25 23:00 UTC] No.44428826[source]▶
I can definitely make this more clear, but this is specifically only changing the home appreciation and asset appreciation rates that produce that $1.5M change. I used the topline numbers at the beginning of the blog post, which is the national 20th percentile for housing growth and S&P growth. Everything else (local factors like price, rent, mortgage interest, property taxes) is held equal.