Embed the BTU Calculator

The cooling or heating capacity a room needs, from its size and the things that change the answer — sun, ceiling height, occupants and a kitchen. Set the values it should open on, then copy the iframe. Your visitors can change them; the widget recomputes against Rule Calculator and never touches your page.

Opening values

Set what the widget shows before anyone touches it. Leave a field as it is and it stays out of the URL.

Room areaCeiling heightSunlightPeople in the room regularlyIs it a kitchenHeating factor for your climateHeight — 1040px

Preview

Paste this

<iframe src="https://rulecalculators.com/embed/btu" width="100%" height="1040" style="border:1px solid #e5e5e5;border-radius:12px" loading="lazy" title="BTU Calculator"></iframe>
<p style="font:13px/1.5 system-ui,sans-serif;color:#666;margin:6px 0 0"><a href="https://rulecalculators.com/calc/btu" style="color:#666">BTU Calculator</a> by <a href="https://rulecalculators.com" style="color:#666">Rule Calculator</a></p>

Free for commercial use. The one condition is the credit link inside the widget, which is how the calculator stays free. Want the numbers in your own markup instead? The same calculator is a JSON endpoint, or see the full BTU Calculator page with its sources and working.