Every calculator we've built
More being added regularly. All show you the number most tools hide.
Why another calculator site?
Most financial calculators show you the payment. We show you the cost. There's a difference.
A $2,023 mortgage payment sounds manageable. $408,000 in interest over 30 years sounds different. Both numbers are true. Most calculators only show you one.
Every tool on TrueNumbers is built to show you the number that changes how you think about a decision — not just the number that closes the sale.
$0K
interest on a typical 30-year mortgage
$0K
investment fees over 30 years at 1%
0 mo
avg break-even to buy vs renting
Real math, not estimates
Full amortization schedules, not simplified formulas.
The number they don't show you
Every calculator surfaces the cost most people never see.
Your data stays in your browser
We never see what you enter. No account required.
How our calculators are different
Real amortization, not shortcuts
Most online calculators use a simplified formula to estimate a single output. Ours build a full month-by-month schedule — the same calculation a lender uses internally — so the numbers you see reflect how your actual loan or investment behaves over time, not just a rough approximation of the end result.
We show the number most tools skip
Total interest, opportunity cost, the gap between a lender's maximum approval and what's actually comfortable — these numbers exist in every calculator's underlying math, but most tools never surface them because the comfortable headline number is easier to sell. We build every calculator to show the uncomfortable number too.
Nothing you enter ever leaves your browser
Every calculation runs client-side, in JavaScript, in the browser tab you're looking at right now. We don't have a server that receives your income, your home price, or your debt balances — there's no account to create and nothing to store, by design rather than by promise.
Frequently asked questions
Is TrueNumbers really free?
Yes — every calculator is free to use, with no signup, no paywall, and no premium tier blocking results. We don't charge for access to any tool on this site.
Do you store my financial information?
No. Every calculation runs entirely in your browser using JavaScript. Nothing you type — income, home price, debt balances, anything — is ever sent to a server, because we don't have a server that receives it.
How accurate are these calculators?
The underlying math is built to match real-world formulas — full amortization schedules, standard DTI calculations, and so on. The accuracy of the result depends on the accuracy of your inputs and assumptions, which we label clearly throughout each tool.
Do you give financial advice?
No. These calculators show you the math behind a decision so you can think it through yourself. They're not a substitute for advice from a qualified financial advisor, accountant, or attorney about your specific situation.
What makes these different from other calculators?
Most calculators show a single headline number — a payment, a rate. Ours are built to also show the number most tools leave out: total interest, opportunity cost, true monthly cost, or the gap between what a lender approves and what's actually comfortable.
Can I trust the results?
The calculations use standard, verifiable formulas, and we're explicit about which numbers are assumptions versus calculations. That said, treat every result as an estimate to inform your thinking, and verify important figures against official documents — like a lender's loan estimate — before making a final decision.
Will you build more calculators?
Yes — we regularly add new tools based on requests from users. Use the contact form to suggest a calculator you wish existed.
Have an idea?
Tell us what calculator you need
We build calculators people actually ask for. If there's a financial decision you're struggling to get a clear answer on — tell us.