Learn real estate math
Plain-English guides. Formulas you can check. No jargon, no fluff.
Updated October 2, 2026
Getting started
- The cap rate formulaWhat cap rate is, how to calculate it, and what it measures.3 min read
- The NOI formulaNet operating income in one formula, before the mortgage.3 min read
- How the 1% rule worksThe fastest rent-to-price screen in real estate.3 min read
- The cash-on-cash formulaWhat your money earns after the mortgage.3 min read
- The DSCR formulaThe lender’s coverage test in one division.3 min read
Metric guides
- What is a good cap rate?The healthy band, and what sits above or below it.4 min read
- Cap rate vs other metricsWhat each ratio measures and when each one lies.4 min read
- How cap rates differ by marketWhy the same yield means different things in different cities.4 min read
- How appraisers use your NOIThe income approach, and how lenders underwrite it.4 min read
- What is a good cash-on-cash return?The bar buy-and-hold investors actually underwrite to.4 min read
- What is a good GRM?The screening multiple, and where it stops being useful.4 min read
- What is a good rental yield?Gross versus net, and the ranges that clear the bar.4 min read
Strategies
- The BRRRR formulaBuy, rehab, rent, refinance, repeat, in one equation.4 min read
- The five financing stages of a BRRRRWhere the money sits at each phase of the cycle.5 min read
- Infinite return, explainedHow a full cash-out refinance zeroes the denominator.4 min read
- When BRRRR works and when it doesn’The four conditions the strategy stands on.5 min read
- The fix and flip formulaNet profit, ROI, and margin on one rehab.4 min read
- The 70% rule for flipsThe maximum-offer screen every flipper runs first.3 min read
- How to source and finance a flipFinding the deal, and the loans that fund it.5 min read
Buying and financing
- What is a mortgage payment made of?Principal, interest, taxes, insurance, and the part that goes away.4 min read
- The mortgage payment formulaOne equation from loan, rate and term to the monthly check.4 min read
- PMI, explainedWhat it costs, and the month it finally stops.4 min read
- What an extra $100 a month doesPriced on a real loan: interest saved and years cut.3 min read
- 15-year vs 30-year mortgageThe payment, the interest, and the risk each one carries.4 min read
Renting and landlords
- What is prorated rent?Partial-month rent, and when it is actually owed.3 min read
- The prorated rent formulaA month into a day, and the days back into rent.3 min read
- 30 days or 31 days?The three billing methods, and how far apart they land.4 min read
- Prorating a move-outThe final month, counted from the 1st.4 min read
- Prorating the first monthMove-in rent, plus the flat move-in costs.3 min read
- Six weeks free, explainedHow a free-rent concession meets a partial month.4 min read
Advanced
- DSCR below 1.0: what happensWhat a lender does when the rent cannot cover the note.4 min read
- DSCR vs DTI vs LTVThree lender ratios, three different jobs.5 min read
- Lender DSCR vs investor DSCRTwo coverage numbers, and why they disagree.4 min read
- Cash-on-cash vs IRR vs total ROIThree return metrics, and when each one answers.5 min read
- The tax side cash-on-cash hidesWhat the year-one ratio leaves off the ledger.4 min read
- The infinite return reality checkWhy a recovered-down-payment deal still carries risk.4 min read
- Three DSCR mistakes that kill loan approvalsThe underwriting errors that sink an application.4 min read