Put our calculators on your own site

Two of our calculators are free to embed on any website: heat pump costs and EPC ratings. One line of HTML each, no account, no cookies and no tracking scripts loaded on your readers. All we ask is that you keep the credit link.

Heat pump cost calculator

Installed cost, the £7,500 Boiler Upgrade Scheme grant, running costs against the reader's current heating, and payback. It runs the same cost model as our full heat pump calculator, and we test every money figure against it, so a reader who follows the link sees the same numbers. It also shows what a dedicated heat pump tariff would cost, which is where most of the saving comes from.

<iframe
  src="https://www.retrofitplanner.co.uk/embed/heat-pump-calculator/"
  title="Heat pump cost calculator"
  loading="lazy"
  style="width:100%;max-width:640px;height:560px;
         border:1px solid #e5e3dc;border-radius:12px">
</iframe>
<p style="font-size:13px">Calculator by
  <a href="https://www.retrofitplanner.co.uk/heat-pump-calculator/">
    Retrofit Planner</a>
</p>

<script>
addEventListener("message", function (e) {
  if (e.origin !== "https://www.retrofitplanner.co.uk") return;
  if (!e.data || !e.data.rpHeight) return;
  var f = document.querySelectorAll(
    'iframe[src*="retrofitplanner.co.uk/embed/"]');
  for (var i = 0; i < f.length; i++) {
    if (f[i].contentWindow === e.source) {
      f[i].style.height = e.data.rpHeight + "px";
    }
  }
});
</script>

EPC rating calculator

Estimates the band from the age, walls, loft, glazing and heating, then ranks the cheapest measures that reach the reader's target band, with points and costs after grants. It runs the same point model as our full EPC calculator, tested against it on band, points and total cost. Useful on any page about selling, letting or improving a home, and on landlord pages before the 2030 band C standard.

<iframe
  src="https://www.retrofitplanner.co.uk/embed/epc-calculator/"
  title="EPC rating calculator"
  loading="lazy"
  style="width:100%;max-width:640px;height:640px;
         border:1px solid #e5e3dc;border-radius:12px">
</iframe>
<p style="font-size:13px">Calculator by
  <a href="https://www.retrofitplanner.co.uk/epc-calculator/">
    Retrofit Planner</a>
</p>

<script>
addEventListener("message", function (e) {
  if (e.origin !== "https://www.retrofitplanner.co.uk") return;
  if (!e.data || !e.data.rpHeight) return;
  var f = document.querySelectorAll(
    'iframe[src*="retrofitplanner.co.uk/embed/"]');
  for (var i = 0; i < f.length; i++) {
    if (f[i].contentWindow === e.source) {
      f[i].style.height = e.data.rpHeight + "px";
    }
  }
});
</script>

The resize script handles both widgets, so if you embed the pair on one page you only need it once.

If your CMS strips scripts

Some editors remove script tags. Drop the script block and set a taller fixed height instead: 900px for the heat pump calculator and 1100px for the EPC calculator. The widget then scrolls inside the frame rather than resizing.

The terms, in plain English

• It is free. Commercial sites included. No account, no key, no usage limit.
• Keep the credit link. The line under the iframe, pointing to the calculator, is the whole price. Leave it as a normal link that search engines can follow.
• Nothing tracks your readers. The widgets set no cookies, load no analytics and make no third-party requests. They need no mention in your cookie banner.
• Do not present them as your own. You can wrap a widget in your own page and write your own introduction, but do not remove the attribution or claim the model.
• We keep them current. When the price cap or the grant changes we update them, and your copy updates with it. If we ever retire a widget we will leave a redirect rather than break your page.

Who this suits

Installers and heating engineers use the heat pump calculator on a service page so a visitor can size the job before calling. Estate and letting agents use the EPC calculator next to listings, where the band is already on the page. Energy and money blogs use either to answer the cost question inside an article instead of sending readers away. Councils and community energy groups use them on advice pages. If you want a widget we do not offer yet, tell us on the contact page.

Technical notes

Frequently asked questions

Are the calculators really free to embed?

Yes, on any site including commercial ones. There is no account, no API key and no limit on page views. The only condition is that you keep the credit link under the widget.

Will they slow my page down?

No. Each widget is 12 to 15 KB with no external requests, no fonts and no analytics, and the snippet sets it to load lazily so it does not download until a reader scrolls near it.

Do I need to mention them in my cookie banner?

No. The widgets set no cookies, use no storage and load nothing from third parties, so there is nothing to consent to.

Can I change the colours or the wording?

Not directly, because everyone shares one copy and that is how updates reach you automatically. You can set the width and the border in the snippet, and each follows your reader's light or dark mode. Ask us on the contact page if you need something specific.

What happens when energy prices or the rules change?

We update the models and every embed updates with them, because your page loads the current version rather than a copy. The figures use the Ofgem cap for October to December 2026 and the £7,500 Boiler Upgrade Scheme grant.

Will the numbers match your own calculators?

Yes. Every money figure in the heat pump widget is tested against the full calculator across a range of property and heating combinations, and the EPC widget is tested on band, points and total cost against the full EPC calculator. A reader who follows the link sees the same numbers with more detail around them.

Try the full heat pump calculator or EPC calculator, which add the carbon saving, the quote form and the detail behind every number.