Just pulled up some old data from September 2023 on mortgage interest rates and found it pretty interesting to see where things were at. The 30-year fixed was sitting around 8.04% back then, with the 15-year coming in at 7.19%. Jumbo mortgages were at 7.85%. Obviously things have shifted a lot since, but it's wild to look back at what mortgage interest rates september 2023 actually looked like.

What caught my attention was how the APR differed from the base rate. Like, the 30-year mortgage interest rates showed 8.04% but the APR was 7.99% when you factored in all the fees. For someone borrowing $100k on a 30-year fixed, monthly payments were running about $737 just for principal and interest. That's a chunk of change and adds up to over $165k in total interest by the end.

The 15-year option was higher at 7.19%, which meant around $910 monthly per $100k borrowed. People always ask me which is better, and honestly it depends on your situation. Faster payoff with 15-year but bigger monthly hit, versus spreading it out over 30 years. The september 2023 mortgage interest rates showed this tradeoff pretty clearly.

What determines these rates anyway? Basically the Fed's decisions, inflation, overall economy health, plus your personal credit score and debt situation. Better credit score means better rates. Keeping your debt-to-income ratio under 43% helps too. And if you can throw down 20% upfront, you skip the PMI which saves money over time.

There's different loan types depending on your situation too. Conventional loans are solid if you've got decent credit. FHA loans let you put down less. VA loans have no required down payment if you qualify. For expensive markets, jumbo loans get you past the standard limits. Anyway, the historical mortgage interest rates data from september 2023 shows how much all these factors matter when you're shopping around.