For publishers, teachers & forums

Embed any calculator, free

All 81 tools drop into your site with one copy-paste snippet. They resize themselves, work on mobile, print the formula on the page, and keep every value in your reader's browser. No signup, no API key, no usage limits — just keep the attribution link.

The licence, in full

Free for any site, commercial or not. No signup, no key, no limits.
Keep the attribution link that ships in the snippet, visible and followable. Restyle it to match your design if you like.
Don't misrepresent the output as financial, tax or medical advice, and don't alter the numbers the tool produces.
That's everything. No other conditions, and you don't need to ask us first.

See it working

A live embed, and the code behind it

This is a real embed of the Compound Interest calculator, running the same snippet you'd paste. Drag a slider — it recomputes live, and the frame grows to fit.

The snippet

<iframe id="empirecalc-compound-interest" src="https://empirecalc.com/compound-interest?embed=1" title="Compound Interest — EmpireCalc" width="100%" height="640" loading="lazy" style="border:1px solid #e2e8f0;border-radius:12px;max-width:560px"></iframe>
<script>(function(){window.addEventListener("message",function(e){if(e.origin!=="https://empirecalc.com")return;var d=e.data||{};if(d.type!=="empirecalc:height")return;var f=document.getElementById("empirecalc-"+d.slug);if(f&&d.height)f.style.height=d.height+"px";});})();</script>
<p style="font:13px/1.5 system-ui,sans-serif"><a href="https://empirecalc.com/compound-interest" target="_blank" rel="noopener">Compound Interest calculator by EmpireCalc</a></p>

The <script> block is the auto-resizer — it checks the message origin, so it only ever responds to EmpireCalc. Drop it if you'd rather keep a fixed height; the iframe still works.

Worth knowing

Embed the exact scenario your article discusses

Every calculator writes its inputs into the URL, so you can hand readers a tool that already shows the numbers you're writing about instead of the defaults. Set the sliders on the calculator page, copy the URL, and add &embed=1:

https://empirecalc.com/compound-interest?principal=25000&rate=7&years=30&embed=1

Use that as the iframe src. Readers can still change anything — they just start where your article does.

All 81 tools

Pick a calculator and copy its snippet

Each button copies a complete, ready-to-paste snippet for that tool — iframe, auto-resizer and attribution link.

Core Sovereign Layer

SaaS Unit Economics LTV, CAC payback & the MRR growth ceiling.
Startup Runway How many months until zero — with dynamic burn.
Freelance Rate Optimizer The bill rate that survives FICA & healthcare.
Equity Dilution Stock-option value across dilution rounds.
ESPP Discount and lookback, as a real return.
CapEx vs OpEx ROI Buy vs lease, by cash velocity.
LLC vs S-Corp The S-Corp tax inflection point.
E-Com Unit Economics DTC contribution margin & break-even ROAS.
Self-Employment Tax The 15.3% FICA bite on freelance profit.
Business Loan Amortization True APR once the origination fee is in.
Break-Even Point The sales volume that covers your costs.
Profit Margin & Markup Margin vs markup, with no sleight of hand.
Freelance Project Quote Price a fixed bid against scope creep.
QSBS Exit Proceeds After-tax startup exit with Section 1202.
RSU Withholding Shortfall The 22% RSU under-withholding trap.
Angel Deal Velocity SAFE-to-exit dilution & return multiple.

Wealth & Leverage

Mortgage Paydown Amortization with payment acceleration.
Rental Cashflow NOI, cap rate & cash-on-cash return.
BRRRR Simulator Buy-Rehab-Rent-Refinance-Repeat seasoning.
FIRE Velocity Safe withdrawal & years-to-freedom curves.
DRIP Compounder Dividend reinvestment compounding.
Rent vs Buy Math Buy vs rent, with down-payment opportunity cost.
Dividend Income Net monthly dividend cash flow & yield-on-cost.
Coast FIRE When your portfolio can coast to retirement.
Mortgage Calculator True all-in PITI monthly payment.
Home Affordability Max price by the 28/36 rule, taxes in.
Mortgage Refinance Breakeven The month a refi repays its closing costs.
Compound Interest Watch contributions snowball into future value.
Roth vs Traditional Today's tax rate vs retirement's — who wins.
Roth Conversion The tax cost of converting, bracket by bracket.
401(k) Match Capture every dollar of employer free money.
HSA Triple Tax The only triple-tax-free account, quantified.
Social Security Breakeven Claim early or wait — the break-even age.
Required Minimum Distribution Project the RMD tax bomb after 73.
Inflation-Adjusted Return Real vs nominal return in today's dollars.
Net Worth Projection Your trajectory and the year you hit your target.

Sustainable Transitions

Solar ROI Payback vs irradiance & net metering.
EV Ownership Cost Total cost of ownership vs ICE.
Remodeling Equity Reno cost vs value added.
Heat Pump Savings Gas vs heat pump utility shift.
Battery Arbitrage Time-of-Use home battery cash yield.

General Utility

Hourly to Salary Real take-home across tax brackets.
Student Loan Refi Interest saved by refinancing.
Debt Payoff Strategy Snowball vs avalanche, head to head.
Credit Card Payoff Escape the minimum-payment trap.
Debt-to-Income Ratio The ratio lenders judge you on.
Marginal vs Effective Tax Your real tax rate vs your bracket.
Capital Gains Tax Short vs long-term tax on a stock sale.
CD vs High-Yield Savings Lock the rate or keep the liquidity.
Emergency Fund Size it, score your coverage, date it funded.
Paycheck Take-Home Salary to net pay, after every deduction.
Debt Snowball Your exact debt-free date, snowball method.

Digital Assets

Crypto Gains Tax Short vs long-term gains modeling.
Impermanent Loss AMM LP loss vs fee APY break-even.
Crypto DCA Modeler DCA vs lump-sum on a volatile path.

Behavioral Magnets

Screentime Bleed Screen hours as opportunity cost.
Subscription Audit The true annual drain of your stack.
Purchasing Power Decay How inflation erodes idle cash.
Budget Compatibility Two spenders, one savings outcome.
Newsletter Valuation Value a newsletter & price ad slots.
Creator Ad Revenue What your views really pay, after the cut.

Biometric & Longevity

BMR & Calorie BMR & calories via clinical equations.
Phenotypic Age (PhenoAge) Biological age from nine blood biomarkers.
VO2 Max & Fitness Age Cardio fitness from field tests.
Heart Rate Zones Five training zones from your heart-rate reserve.
Health Insurance Optimizer HDHP vs PPO by your real utilization.
Macro Calculator Protein, carbs & fat for your goal.
Body Fat (Navy Method) Body fat % from a tape measure.

Asset & Tech Architecture

Wheel Offset & Fitment Poke, inset & speedo from a wheel setup.
AI Compute Optimizer API vs self-hosted GPU tipping point.
Geo-Arbitrage Velocity Tax + cost-of-living relocation gains.
Cloud Infrastructure Bloat Find the waste in your cloud bill.

Family & Protection

529 College Savings Your 529 vs tomorrow's tuition bill.
Term Life Insurance Needs Size coverage with the DIME method.
Childcare vs Second Income Does the second paycheck survive daycare?
Disability Insurance Needs Insure the income disability would erase.

Auto & Mobility

Car Affordability Max car price by the 20/4/10 rule.
Lease vs Buy a Car True cost of leasing vs buying, equity in.

Travel & Rewards

Credit Card Points Value The real cents-per-point of a redemption.
Credit Card Rewards Earnings What your spending actually earns in points.
Travel Budget Planner Plan a trip that fits your budget.

Questions

Is embedding EmpireCalc calculators free?

Yes — free for any site, commercial or not, with no signup, no API key and no usage limit. The one condition is that you keep the attribution link that ships in the snippet. That link is the only thing we ask for in return, and it is what makes offering the embeds sustainable.

Do I need to keep the attribution link?

Yes. The snippet includes a visible link back to the calculator on EmpireCalc, and keeping it is the condition of the licence. You are welcome to restyle it to match your site — change the font, size or colour — as long as it stays visible to readers and remains a real, followable link (no nofollow, no hiding it off-screen).

Does the embed resize itself?

Yes. The embedded page measures its own content and posts its height to the parent window; the small script in the snippet listens for that message and adjusts the iframe. The result is no inner scrollbar and no clipped tool at any width. The listener checks the message origin before acting, so it only ever responds to EmpireCalc. If you drop the script, the iframe still works — it just keeps the fixed 640px height.

Does the embed track my visitors?

The embedded calculator runs the same analytics as the rest of the site, and it computes entirely in your visitor's browser — no inputs are transmitted to us or stored on our servers. Values a visitor enters stay on their device. Nothing is written to your page beyond the iframe and the attribution link.

Can I embed a calculator with values already filled in?

Yes, and this is the most useful thing about these embeds. Every calculator encodes its inputs in the URL, so set up the exact scenario you want on the calculator page, copy the URL from your address bar, and append &embed=1 to it. Use that as the iframe src and your readers land on the numbers your article is discussing rather than the defaults.

Will the embed break when you update the calculator?

No. Embeds point at a live URL, so they pick up fixes and updated figures automatically — tax constants, for example, are updated site-wide each year from a single file. Slugs are permanent, so an embed you place today keeps working.