Free calculator widgets for your site
Reviewed by the ClearTally editorial team · Last updated August 2, 2026 · Methodology & sources
If you write about mortgages, sell houses, or run a personal finance site, a working calculator on the page tends to hold people better than a paragraph explaining the math.These 8 are free to embed.Copy one line of HTML, paste it where you want the calculator, done — no signup, no API key, no view limit.
They're the same calculators we run ourselves, served from our site rather than copied onto yours. That's the part worth knowing: when a tax bracket or contribution limit changes, your embed shows the new number without you touching it. There's no second version to go stale.
The only condition is the credit line that comes with the snippet, below the calculator. Please leave it there.
Pick a calculator
Mortgage Calculator
Estimate your full monthly mortgage payment — principal, interest, property tax, homeowners insurance and HOA dues — plus total interest and the complete amortization schedule.
Fits a 1938px-tall frame · works down to 320px wide
Closing Cost Calculator
Estimate closing costs line by line — lender fees, title, taxes, prepaids — and the total cash you'll need to close.
Fits a 1847px-tall frame · works down to 320px wide
Home Affordability Calculator
See how much house you can afford from your income, debts, and down payment using the 28/36 rule.
Fits a 1464px-tall frame · works down to 320px wide
Down Payment Calculator
Work out your down payment amount, the resulting loan and loan-to-value, whether PMI applies, and how much to save each month to reach it.
Fits a 1391px-tall frame · works down to 320px wide
Rent vs Buy Calculator
Compare the true cost of renting vs buying over the years you plan to stay, including equity, appreciation, and the break-even year.
Fits a 2539px-tall frame · works down to 320px wide
Auto Loan Calculator
Calculate your monthly car payment, total interest, and payoff timeline.
Fits a 1096px-tall frame · works down to 320px wide
Compound Interest Calculator
Project how your savings or investments grow over time with compound interest.
Fits a 827px-tall frame · works down to 320px wide
FIRE Calculator
Find your FIRE number and the age you'd reach financial independence — from your savings, expenses, expected return, and withdrawal rate.
Fits a 1135px-tall frame · works down to 320px wide
What the snippet does
Two elements. An <iframe> pointing at the calculator, and a <p> underneath it with the credit link. Both sit in your HTML, so you can move them, wrap them, or restyle the paragraph to match your site.
The iframe is set to width="100%" with a max-width of 680px, so it fills a narrow column and stops before it gets unwieldy in a wide one. The height is fixed per calculator because each one is a different length: the compound interest calculator needs 827px and the rent vs buy calculator needs 2539px, since it stacks two full cost columns on a narrow screen. Every number was measured at 320px wide with results on screen rather than estimated, so nothing clips on a phone.
Nothing else loads. No analytics script, no ad code, no font or tracker from a third party — the widget makes requests to our domain and nowhere else.
Questions
Yes, and there's no signup, no API key, and no limit on page views. All we ask is that you keep the credit line underneath the calculator — that link is the only thing we get out of this.
Barely. The iframe is marked loading="lazy", so a browser won't fetch it until the visitor scrolls near it — if it's below the fold on a page nobody scrolls, it costs nothing at all. The widget itself is stripped down compared to our own pages: no charts, no analytics scripts, no ad code. That drops it to about 685 KB of JavaScript against 2.4 MB for the full page, and none of it is fetched from a third party.
No. The widget is served from our site, so the moment we update a bracket or a contribution limit your embed shows the new figure. You paste it once and leave it alone. That also means the calculation on your page is always the same one running on ours — there's no stale copy to drift out of sync.
Auto-resizing needs a script running on your page listening for messages from ours, and we'd rather not ask you to run our JavaScript. So each widget has a height measured at 320px wide with results showing — the tallest case — which means it fits on a phone and has a little slack at the bottom on a desktop. If you'd rather it were tighter, change the height number in the snippet; nothing breaks.
Not at the moment. Same-origin rules stop your CSS reaching inside the frame, and we haven't built theming options. You can change the width, the height, and the border in the snippet's own style attribute, which covers most of what people want.
We don't retire URLs — anything published keeps working, and if a calculator is ever replaced its address redirects to whatever replaced it. Your embed would follow that redirect rather than break.
These calculators produce estimates for planning, not financial advice. Figures depend on inputs a calculator can't see — your credit, your lender's pricing, local tax rules — so treat the output as a starting point and confirm anything you're acting on with the institution involved.