ABOUT THIS CALCULATORRent vs Buy Calculator
Most rent-vs-buy calculators compare a mortgage payment to a rent cheque and call it an answer. This one simulates both futures month by month and compares what you are actually worth at the end of each. More than 50 variables feed that simulation.
THE METHODOLOGYHow the engine works — every formula, every assumption, in fullThe amortisation and how the payment splits. The exact PMI termination rule. Why property tax, maintenance and insurance are reassessed annually against the projected value but HOA is not. Why rent steps at lease renewal rather than every month. What break-even is, and the three things it is not. The whole Q+ tax chain, ARM caps, refinance and early-payoff math — each with a worked example in real dollars, and each read out of the code that runs.Read the full breakdown →Which data went into those formulas, and the date each source was last refreshed, is on the data and methods page.
Common questions
What does the DwellQ rent vs buy calculator actually model?
It runs both paths month by month over your whole horizon rather than comparing a mortgage payment to a rent payment. The buy path carries principal, interest, property tax, homeowners insurance, PMI until it terminates, maintenance, HOA and closing costs at purchase — maintenance covers the roof and the furnace, so there is no separate capital-reserve line. Selling costs are netted out of equity in every month of the chart rather than only at the exit, so the buy line always answers what you would walk away with if you sold that month. The rent path carries rent, renters insurance, and the invested balance of every dollar the buy path tied up — the down payment first, then any month where owning costs more than renting. More than 50 inputs feed those two schedules.
What does the break-even year mean here?
It is the first month where the buy path’s net worth — home equity after an assumed sale, minus selling costs — overtakes the rent-and-invest path’s portfolio. It is not the month your payment beats rent, and it is not the month you have "paid off" your closing costs. Selling before break-even means the analysis says renting would have left you with more money.
How does it handle taxes?
The free calculator applies property tax and models PMI termination. Q+ adds the tax chain: itemized versus standard deduction, mortgage interest and SALT under the current cap, and the timing rule that a year’s deductions are credited the following January because that is when you file. Tax benefits therefore appear from year 2, not month 1.
Is the calculator free, and does it sell my information?
The core analysis — net worth comparison, break-even, monthly cost breakdown, equity charts — is free with no signup. There are no affiliate links and no lender referrals; DwellQ earns nothing from which answer you get. Q+ is a one-time purchase that adds tax modeling, ARM scenarios, refinance simulation, and PDF reports.
How accurate is it?
The arithmetic is checked against independent reimplementations across more than 1,500 scenarios before any change ships, and every formula is inspectable through "Show the Math" on any result. But accuracy of the arithmetic is not prediction: appreciation, investment returns, and future rates are assumptions you supply, and the output is a projection under those assumptions, not financial advice.