Free Calculator Widgets to Embed on Your Site
Every calculator below runs live on your page from a single iframe. Copy the snippet, paste it into your HTML, done — no signup, no API key, no script to maintain. 8 tools are available.
Terms — short version
- Free for any site, commercial or not — no signup, no API key, no usage limit.
- Keep the “Powered by WattSimple” link visible and followable. That link is the price.
- Don't modify the widget's output, strip the attribution, or wrap it in your own branding.
How to embed one
- 1
Pick a calculator
Choose the tool that fits your page from the list below and preview it to confirm it is the one you want.
- 2
Copy the iframe snippet
Hit Copy under that calculator. The snippet is a single iframe tag — no script, no dependency.
- 3
Paste it into your page
Paste into an HTML or embed block: a Custom HTML block in WordPress, an embed block in Squarespace or Wix, or straight into the template of a hand-built site.
- 4
Adjust the height if needed
The snippet ships at 720px. In a narrow column the widget stacks taller, so raise the height attribute until there is no scrollbar or empty gap.
Available widgets
EV Charging Cost Calculator
Estimate the cost to charge your EV at home or in public based on battery size, charge level, and your electricity rate.
<iframe src="https://wattsimple.com/embed/ev-charging-cost" title="EV Charging Cost Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>EV Charging Time Calculator
How long it takes to charge an electric car (EV) on Level 1, Level 2, or DC fast charging — from any starting battery level.
<iframe src="https://wattsimple.com/embed/ev-charging-time" title="EV Charging Time Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>Electricity Cost Calculator
Price any kWh amount from your bill, or work out the running cost of an appliance from its wattage, hours of use, and your electricity rate.
<iframe src="https://wattsimple.com/embed/electricity-cost" title="Electricity Cost Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>Solar Panel Payback Calculator
Estimate how many years a solar system takes to pay for itself from the electricity it offsets — and its lifetime savings.
<iframe src="https://wattsimple.com/embed/solar-panel-payback" title="Solar Panel Payback Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>EV vs Gas Cost of Ownership Calculator
Compare the total cost of owning an EV versus a gas car over time — fuel, maintenance, and financing.
<iframe src="https://wattsimple.com/embed/ev-vs-gas-cost" title="EV vs Gas Cost of Ownership Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>EV Loan & Payment Calculator
Calculate monthly payments, total interest, and payoff for financing an electric vehicle.
<iframe src="https://wattsimple.com/embed/ev-loan-payment" title="EV Loan & Payment Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>Heat Pump Cost Calculator
Estimate heat pump installation cost by size and type — ducted, ductless, or geothermal — with an equipment, labor, and adder breakdown and a cost-by-type comparison.
<iframe src="https://wattsimple.com/embed/heat-pump-cost" title="Heat Pump Cost Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>Home EV Charger Installation Cost Calculator
What electric car charger installation costs at home — Level 2 charger, panel, wiring, and labor — as a planning range.
<iframe src="https://wattsimple.com/embed/home-charger-install-cost" title="Home EV Charger Installation Cost Calculator by WattSimple" width="100%" height="720" style="border:1px solid #e2e8f0;border-radius:12px;max-width:768px" loading="lazy"></iframe>Frequently asked questions
Want a widget we don't offer yet?
The embeddable set covers the tools that stand alone without extra context. If you need a different one — or a size that fits your layout better — get in touch. Browse every calculator to see what exists.