Keys & Cents

Hi, I’m Sterling.

I’m the owl behind Keys & Cents. My job: make sure nobody buys a home knowing only the mortgage payment.

Sterling the owl in round glasses and a teal bow tie, holding a golden key

Our mission

Keys & Cents is an independent, reader-supported publication. We build free, plain-English tools that show what a home really costs, every month: taxes, insurance, PMI, HOA, upkeep and utilities included. The name is a little wordplay: keys for the home, cents for the money, and (we hope) some common sense along the way.

What we promise

  • Every tool is free and runs in your browser. We don’t ask for your email to show you a number.
  • Every local figure has a public source and a date on the page.
  • Assumptions are labeled as assumptions, and you can change all of them.
  • Sponsors never change the math. See our disclosure.

Methodology

True monthly cost = principal & interest (standard fixed-rate amortization) + property tax (rate × price ÷ 12) + insurance (annual ÷ 12) + HOA + PMI (annual rate × loan ÷ 12, only when the down payment is under 20%) + maintenance (percent of price ÷ 12) + utilities. PMI is estimated to end when the scheduled balance reaches 78% of the original price.

Affordability: “comfortable” keeps the housing payment (P&I, tax, insurance, HOA, PMI) within 28% of gross monthly income and total debts within 36%; “stretch” allows total debts up to 43%. We solve for the price that fits exactly.

Rent vs buy: a month-by-month simulation. The renter invests the down payment and closing costs plus any monthly savings; the buyer invests any month owning is cheaper. Buyer net worth = home value − selling costs − loan balance + invested savings. Income-tax effects are ignored.

Local data: U.S. Census Bureau American Community Survey 2024 1-year estimates (median home value B25077, median real estate taxes B25103, median gross rent B25064, median household income B19013, median owner costs B25088), via the Census Reporter API. The effective tax rate is our approximation (median taxes ÷ median value). Mortgage rates: Freddie Mac PMMS weekly 30-year average (7.32% for October 22, 2026).

Assumptions where no reliable local public data exists: insurance $2,400/yr, PMI 0.6%/yr, maintenance 1%/yr. Change them to match your quotes.

Utilities: every calculator, county page and the planner use $275/mo, the Census ACS 2024 1-year PUMS median of separately paid electricity, gas, water/sewer and other fuel for owner-occupied 3-bedroom homes. It’s a national figure; your bills depend on climate, home size and local rates, so swap in the seller’s last 12 months if you can.

Not advice

We’re a calculator and a guide, not a lender, broker, tax advisor or lawyer. Use our numbers to ask better questions, then get real quotes.

Say hello

Spotted a bug, have an idea, or want to sponsor the newsletter? Email [email protected] or find us on X.