Know what you can actually afford.

No. There's no back end to send it to. The whole calculation runs in JavaScript in your browser tab. "Save to this device" writes to your browser's own local storage, which never leaves your machine, and "Clear saved" deletes it.

It is, but it's 28% of gross, and the share Openbook leads with is of take-home pay. Take-home is the smaller number, so the same payment looks like a bigger percentage of it. Three ratios are in play and only two of them are the rule: housing ÷ take-home, housing ÷ gross (what the 28 measures, the "front-end" ratio), and housing plus every other debt ÷ gross (what the 36 measures, the "back-end" ratio). On the example household those are 36%, 24% and 33% — so it clears the rule on both counts, even though the first figure is the one that catches your eye. The rules-of-thumb section below prices each rule out against your own numbers, so you can check them rather than take our word for it.

Because a pre-approval is a ceiling, not a recommendation, and the ceiling is higher than most people expect. A conventional loan applies no cap at all on the housing share of your income — the 28% figure you may have read is advice, not a rule — and total debt-to-income can run to 45%, or 50% through Fannie Mae's automated underwriter, or 57% on an FHA loan with strong compensating factors. That calculation sees gross pay and the debts on your credit report. It doesn't know about your 401(k), your health premiums, your childcare or the tax you actually pay. Openbook subtracts all of it first, which is why the number is smaller — and why it's the one you can live in.

They're measuring different things, which is why they disagree. Ramsey's 25% is of take-home pay and assumes a 15-year loan, so it lands lowest by some distance. The Money Guy's 25% is of gross income. The 28/36 rule is also gross, and despite how often it's quoted it's advice — no lender enforces it. Two of the lines aren't advice at all: the federal cost-burden threshold at 30% of gross is a statistical marker, and the approval limit is simply the most a lender will lend you. Openbook's own number is none of the above: it's your take-home pay minus the things you actually spend it on. Run them all, see where yours falls, and treat the rules you miss as questions rather than verdicts — and the ceilings you pass as warnings, not permission.

Two reasons compounding. First, 25% of take-home pay is a much smaller figure than 25% of gross — tax alone is usually a fifth to a third of the difference. Second, the rule specifies a 15-year fixed mortgage, and a 15-year payment is roughly 35% higher than a 30-year one on the same loan. Openbook prices that line on 15 years because that's what the rule says; pricing it on 30 would be quoting the number without the condition attached to it.

Federal tax uses the published marginal brackets and standard deduction for your filing status, plus Social Security and Medicare including the additional Medicare surtax. State tax uses each state's own published rate or brackets, applied to the same taxable-income base — it doesn't model state-specific deductions or credits, and local income tax isn't included. Treat it as a solid estimate, not a return.

They're broad national estimates by credit tier, loan term and state — the kind of figures that get you in the right neighbourhood. PMI steps up at the usual loan-to-value cutoffs and scales with your credit tier, whether or not the rate itself is a real quote. Have an actual number for either? Switch the rate to "I know my rate," or the insurance to "I know my premium," and enter it.

On a refinance, yes, routinely — but this is a purchase calculator, and a purchase is different. On a conventional purchase loan, which is what these figures model, closing costs aren't added to the loan balance; you either bring cash for them or negotiate around them, typically through a seller concession (the seller credits some of the price back at closing) or a lender credit (the lender pays them in exchange for a slightly higher rate, which lowers your affordable price the normal way — through the rate the ledger already uses, not through a bigger loan). FHA and VA purchase loans allow rolling in a narrow, named cost — FHA's upfront mortgage insurance premium, VA's funding fee — and USDA loans can fold costs in only when the home appraises above the price, neither of which this calculator assumes. So "Cash to close" staying separate from the price above isn't an oversight; it's the accurate shape of a standard purchase, where the two really are different pools of money — by default. If you'd rather the estimate not outrun what you can actually bring to the table, enter how much cash you have under "Total cash you have available" in the home & loan step. If it's tight, the down payment gives way first — down to $0 if it has to — to keep the price as close as possible to what the paycheck alone would allow; only once no down payment can make both fit does the price itself come down too.

Yes — "Saved views" keeps a named library of them. Save the numbers as they are now, change something, save that under another name, and switch between them in a click. The list shows the price each view works out to, and ticking two or more puts their ledgers side by side, row for row, so you can see which line moved rather than just that the answer changed. Any row with parts inside it opens — tap Debts and you get each debt, one line per scenario, so "$730 against $280" becomes "the car loan, ticked off" — a scenario that buys less house because the 401(k) went up reads very differently from one that buys less because a car loan came back. With exactly two ticked you also get a difference column. Like everything else here they're stored on your device only, and "Delete saved data" removes them after telling you which ones it's about to delete.

Yes, at whichever scope fits. "Copy share link" in the Manage menu packs just the numbers on screen. Open "Saved views" and each one has its own "Share" button — that sends one scenario, and it lands on their screen and in their library at once, so they don't have to re-save it to compare it against their own. "Share all views" sends your whole library in one link. Every one of them works the same way for the person receiving it: they open the link and it's already loaded, no pasting required — the numbers travel in the link itself, after a # a browser never sends to any server, so nothing is uploaded and nothing sits in anyone's server logs. Got a code as plain text instead of a tappable link (read aloud over the phone, say)? "Paste a code" still takes it. Pasting a views-only link or code never touches what's on their screen — it only adds to their library.

A link, and nothing else. It opens your own phone's Messages app with a short message pre-filled — "here's a calculator worth trying," plus the page's plain address — and you send it exactly like any other text, from your own number, through your own carrier. It never includes your salary, your debts, or anything else in this form; the person who gets it opens the same empty page you started from. If you want to send your actual numbers, that's a different button — "Copy share link," or a saved view's "Share" — and yes, that's a link too, but a longer one: your numbers travel after a # in the address itself, which is why it's a specific button rather than something you'd type by hand. The two are kept apart on purpose: an invite is safe to send to anyone without a second thought, and a share link is your real figures, worth sending only where you'd want anyone to have them.

No. Openbook is a calculator, not an adviser, and it isn't affiliated with any lender, bank or insurer. It's a much better starting point than a gross-income rule of thumb, but talk to a real professional before you sign anything.