Home Affordability afford
Income, debts, rate and down payment in; the lender-style ceiling price out, with the PMI flag and the honest gap to comfortable.
Open Home AffordabilityHONEST HOME MATH
Calculators that show the full cost of a home, with the raw math one click away. The house never flatters you.
Buying Math: ten calculators, live now
Closing-Cost Decoder closing
Loan amount and county transfer-tax tier in; every line item, the cash-to-close, and whether your seller credit can actually be used.
Open Closing-Cost DecoderPMI Calculator pmi
Down payment percent in; the PMI band, the month it can be removed at 80% and drops off at 78%, and the pay-it-or-avoid-it math.
Open PMI CalculatorRate Comparison rate
Two lender offers side by side: note rate vs APR, what the points really buy, and the month the cheaper-rate offer breaks even.
Open Rate ComparisonRefinance Break-Even refi
Current loan vs a new rate and its closing costs; the months to recoup, plus the term-reset interest the monthly savings hide.
Open Refinance Break-EvenExtra-Payment Lab extra
A monthly extra principal amount in; the interest saved, the months cut, and the honest comparison to what that cash could earn elsewhere.
Open Extra-Payment LabARM vs Fixed arm
A fixed rate against an adjustable one with its caps; the worst-case payment path year by year and what each costs over your stay.
Open ARM vs FixedDTI Decoder dti
Front-end and back-end debt-to-income ratios against the 28/36 bands, and the exact dollars between you and a yes.
Open DTI DecoderDebt Payoff debt
Snowball against avalanche on the same budget, side by side: payoff month for every debt and the total interest each method costs.
Open Debt PayoffW-4 Withholding Estimator w4
Pay, filing status and current withholding in; the W-4 step values that hit your target refund and the over/under-withholding band.
Open W-4 Withholding EstimatorEvery lane
Buying Math10 liveAffordability, closing, PMI, rates, refi, ARM, DTI, debt, W-4.
Ownership50 plannedRepairs, systems and upkeep. Arrives in a later version.
Household Money29 plannedEnergy, water and monthly bills. Arrives in a later version.
Seasonal2 plannedAttic and crawlspace season prep. Arrives in a later version.
Renter path4 plannedRenters insurance, roommates and reletting. Version 1.1.
Zero retention: your numbers never leave this browser
Every calculation on HomeSmith runs in JavaScript on your own device. Your income, debts, balances and tax details are never sent to a server, never logged and never sold. There is no account to create and no email to hand over.
Persistence note: so your numbers survive a reload, each calculator saves its inputs in this browser's localStorage under keys that start with homesmith:v1:. That storage stays on this device. Reset a single calculator with its Reset button, or wipe all of them here:
Verify it yourself in DevTools:
- Open DevTools (F12, or Cmd+Option+I on a Mac) and choose the Network tab.
- Open any calculator and type new numbers. No request carries your inputs; the only calls are one anonymous
page_viewcount per page and, if you click a thumb, your vote. - Choose Application, then Local Storage, to see exactly what is saved and delete it.
Learn more about HomeSmith
What is HomeSmith?
HomeSmith is a set of honest-math calculators for people buying, owning or renting a home. Each calculator takes the numbers you actually have, works the arithmetic in plain view and ends in a True Cost Verdict: one plain-language sentence that says what the result means for you, with the raw math one click away.
HomeSmith is built on one rule: the house never flatters you. Lender pre-approvals, listing sites and mortgage ads tend to show the largest number that could work. HomeSmith shows the number that does work, names the inputs that produced it and flags the costs that usually get left out, such as PMI, escrow reserves and the interest hidden in a reset loan term.
How does a True Cost Verdict work?
- Pick a lane in the header. Buying Math is live today with ten calculators.
- Enter your own numbers. Every field shows its unit, checks its range when you leave it, and keeps your input in this browser.
- Read the live results. Teal figures are computed values; small chips show the change, range or band behind each one.
- Read the verdict box. Its border is teal for OK, amber for WARN and red for BAD, and its sentence names the inputs it used.
- Open Show the raw math to check every step, formula and assumption before you trust the answer.
Which calculators are in the Buying Math lane?
- Home affordability: the 28/36 ceiling price and a more comfortable 25/33 price, with PMI, tax, insurance and HOA counted in the payment.
- Closing-cost decoder: an itemized estimate split into true fees and prepaids, plus the seller-credit cap that decides how much of a credit you can actually use.
- PMI calculator: the PMI band for your down payment and credit score, the month you can request removal at 80 percent and the month it drops off at 78 percent.
- Rate comparison: two lender offers side by side with note rate, APR, upfront cost and the break-even month for discount points.
- Refinance break-even: a simple and a true break-even that counts the slower principal paydown of a reset term.
- Extra-payment lab: interest and months saved by paying extra principal, with the liquidity trade-off stated plainly.
- ARM vs fixed: the worst-case payment path under your caps, year by year, against a fixed-rate loan.
- DTI decoder: front-end and back-end ratios, the 28/36 bands and the exact dollars between you and a yes.
- Debt payoff: snowball and avalanche on the same budget, with payoff months and total interest for each method.
- W-4 withholding estimator: projected refund or balance due, the W-4 step values that reach your target, and your take-home per paycheck.
Why does HomeSmith show ranges instead of recommendations?
Mortgage rates, property taxes, title fees and PMI premiums all vary by lender, county and credit file. A single precise-looking number would be false confidence. HomeSmith shows the range where variance is real, for example the affordability price at your rate plus and minus half a point, or a closing-cost band of 15 percent either side of the estimate.
HomeSmith does not tell you which loan to take or which house to buy. The verdict states what the math says about the inputs you gave it, and the decision stays yours.
How is affordability different from what a lender approves?
Affordability is the price whose full monthly cost fits your budget with room left for life. Lender approval is the most a lender is willing to risk, and automated underwriting can approve a back-end debt-to-income ratio near 50 percent. That approval says nothing about savings, childcare, commuting or repairs.
HomeSmith reports the classic 28/36 ceiling as a maximum, a 25/33 figure as a more comfortable target, and the gap between the two in dollars so you can decide where to land.
What does the 28/36 rule mean?
The 28/36 rule is a lending guideline that caps housing costs at 28 percent of gross monthly income (the front-end ratio) and all monthly debt payments, housing included, at 36 percent (the back-end ratio). Housing costs here mean principal, interest, property tax, homeowners insurance, HOA dues and any mortgage insurance.
FHA loans allow 31/43, and many lenders go higher with strong credit or large reserves. The DTI decoder shows where you sit in each band and how many dollars of monthly payments stand between you and 36 percent.
When does PMI go away?
Private mortgage insurance on a conventional loan can be cancelled at your request once the scheduled balance reaches 80 percent of the home's original value, provided your payment history is clean. It must end automatically when the scheduled balance reaches 78 percent, or at the midpoint of the loan term, under the Homeowners Protection Act.
The PMI calculator finds both months on your amortization schedule and totals what you will pay until each one, next to the extra cash it would take to avoid PMI entirely.
Is refinancing worth it?
Refinancing is worth it when the true break-even month arrives well before you expect to sell or refinance again. The simple break-even divides closing costs by monthly savings. The true break-even also counts how much principal you have paid down on each path, which matters when a new 30-year term restarts the clock.
A lower payment can still cost more over the life of the loan. The refinance verdict says so whenever the reset term adds lifetime interest.
Who is HomeSmith for?
- First-time buyers who want to know the real monthly cost before talking to a lender.
- Owners deciding between refinancing, paying extra principal or leaving the loan alone.
- Households paying down debt before a mortgage application.
- Anyone tuning a W-4 so a refund or a bill does not arrive as a surprise.
- Renters weighing when, or whether, buying makes sense, as the Renter path arrives.
What is coming to HomeSmith next?
HomeSmith is organized into four lanes plus a Renter path. Buying Math is live. The Renter path arrives in version 1.1, followed by Ownership for repairs and home systems, Household Money for energy and monthly bills, and Seasonal for attic and crawlspace prep. Every new calculator follows the same pattern: your inputs, live math and a True Cost Verdict.
Frequently asked questions
Is HomeSmith free to use?
Yes. Every calculator is free, needs no account and has no usage limit. There is nothing to upgrade to and no lead form between you and the numbers.
Does HomeSmith send my income or debts anywhere?
No. All math runs in your browser. Your inputs are saved only in this browser's localStorage so they survive a reload, and the only network calls are an anonymous page-view count and an optional thumbs-up or thumbs-down vote.
Why does the affordability number look lower than my pre-approval?
A pre-approval tells you the most a lender will risk, often at a 43 to 50 percent debt-to-income ratio. HomeSmith shows the 28/36 ceiling and a more comfortable 25/33 figure, and it counts property tax, insurance, HOA dues and PMI in the payment.
How accurate are the closing-cost and PMI estimates?
They are national-typical estimates shown as ranges. Title rates, transfer taxes and PMI pricing vary by county, insurer and credit file, so your Loan Estimate is the binding number. Use HomeSmith to know which lines to question.
Are the W-4 numbers tax advice?
No. The W-4 estimator uses the published 2026 federal brackets, standard deductions and child tax credit for a single job, federal tax only. It is a planning estimate; two-earner households should confirm with the IRS Tax Withholding Estimator.
How do I delete my saved numbers?
Use the Clear saved inputs button on this page or the Reset button on any calculator. You can also clear site data for this domain in your browser settings; HomeSmith keeps no copy anywhere else.