How much of take home pay is reasonable to put towards mortgage?

I think percentages are a poor way of measuring what’s right for an individual situation. Percentages work for general guidance.

What matters most is free cash flow after mortgage, taxes, insurance, and utilities. Find a number you are comfortable with for all your other expenses in life…

I think white coat investor says not to go over 3 times your salary (I assume he means total not take home).

That doesn’t really work for all cases

If you make 200k a year, you can manage more then 20%

If you make 50k a year, 20% is too much

It just all depends, do you have car notes? Do you have kids in private schools?

We have no car notes and a kid in daycare. We save 30% pretax in Roths and brokerage, and still have around 32% take home going to mortgage and it’s fine.

Really depends on situation.

My wife and I are in our mid/late 30s. Our current home’s total price (when purchased in Nov 2021) was right at our combined gross income. Total monthly payments are about 17% of monthly net income after 401k contributions and tax withholdings. We can easily manage payments and save a bit for upgrades and repairs while maxing our 401ks and putting away some cash in a 529 plan for our daughter. It’s an older house with “old house” issues (so there is always that risk of a major repair), but it’s far more house than what we’ll ever grow out of and we’ll stay so long as the neighborhood remains safe. And I can live with a house that has older style fixtures in a couple of rooms. We could have afforded a more expensive home but I am glad we didn’t go that route (although almost nothing else was for sale at the time anyways).

Our previous house when we lived in Memphis was sold for an amount roughly equal to 3x our annual gross income. Our mortgage was closer to 35% of our total net after 401k contributions. It was also an older house that needed some repairs, but we got lucky that it appreciated significantly while we owned it and nothing major happened to it. That note was still difficult to handle for us but we made it work, especially since we both drove a couple of older, unfashionable but reliable domestic cars without notes. And we also didn’t have state income tax there. Those numbers are possible if you don’t have kids, but absolutely not recommended unless you are certain your income will grow quickly or if you otherwise play excellent defense against the consumption lifestyle. Looking back on that, I am very surprised we made it work and still put away a few bucks. We ate a lot or cheap food and rarely went out. I might have preferred to buy a cheaper flat and spent some more money traveling in those days.

If you want an overly simplistic rule of thumb - I would stick to 1.5x gross as a general rule for total mortgage, but there is a huge asterisk by that because everyone’s situation is different. And not every US city is equally safe/risky when it comes to real estate downturns either. And not every home buyer has to worry about kids coming into the picture and changing everything or may already have high debt service obligations for things like student loans.