<!-- Braindumps appliance running cost calculator (UK): what a heater, dehumidifier, electric blanket or air fryer costs to run. Self-contained: no external files. -->
<div id="bd-arc">
<style>
#bd-arc{--bd-red:#d63333;--bd-line:rgba(127,127,127,.35);--bd-soft:rgba(127,127,127,.08);font:inherit;color:inherit;max-width:760px;margin:1.5em 0}
#bd-arc *{box-sizing:border-box}
#bd-arc [hidden]{display:none!important}
#bd-arc fieldset{border:1px solid var(--bd-line);border-radius:10px;padding:14px 16px 6px;margin:0 0 14px;min-width:0}
#bd-arc legend{font-weight:700;padding:0 6px}
#bd-arc .grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:0 14px}
#bd-arc label{display:block;font-size:.92em;margin-bottom:10px}
#bd-arc input,#bd-arc select{width:100%;padding:9px 10px;margin-top:4px;border:1px solid var(--bd-line);border-radius:6px;font:inherit;background:transparent;color:inherit}
#bd-arc select option{color:#000;background:#fff}
#bd-arc .hint{display:block;font-size:.85em;opacity:.8;margin-top:3px}
#bd-arc .result{border:2px solid var(--bd-red);border-radius:10px;padding:12px 16px;background:var(--bd-soft)}
#bd-arc .big{font-size:1.6em;font-weight:700;margin:0 0 4px}
#bd-arc table{width:100%;border-collapse:collapse;margin:8px 0 0}
#bd-arc td,#bd-arc th{padding:6px 0;border-bottom:1px solid var(--bd-line);text-align:left;font-weight:normal}
#bd-arc th{font-weight:700;font-size:.9em}
#bd-arc td:last-child,#bd-arc th:last-child{text-align:right;font-variant-numeric:tabular-nums;white-space:nowrap}
#bd-arc .res td:last-child{font-weight:700}
#bd-arc .cmp td:nth-child(2),#bd-arc .cmp th:nth-child(2){text-align:right;font-variant-numeric:tabular-nums;padding-left:8px}
#bd-arc .note{margin:10px 0 0;font-size:.92em}
#bd-arc details{margin-top:10px}
#bd-arc summary{cursor:pointer;font-weight:700}
#bd-arc pre{white-space:pre-wrap;font-size:.85em;margin:8px 0 0;background:transparent;border:0;padding:0}
</style>

<fieldset>
<legend>The appliance</legend>
<div class="grid">
<label>Appliance<select id="bd-arc-app"></select></label>
<label>Power (watts)<input id="bd-arc-w" type="number" min="0" step="10" value="2000" inputmode="decimal"><span class="hint">On the label or plug, in W (or kW × 1,000).</span></label>
<label>Time at full power (%)<input id="bd-arc-duty" type="number" min="1" max="100" step="5" value="100" inputmode="decimal"><span class="hint">Lower it if a thermostat switches it off part of the time.</span></label>
</div>
</fieldset>
<fieldset>
<legend>How you use it</legend>
<div class="grid">
<label>Hours switched on per day<input id="bd-arc-h" type="number" min="0" max="24" step="0.5" value="4" inputmode="decimal"></label>
<label>Days per week<input id="bd-arc-d" type="number" min="1" max="7" step="1" value="7" inputmode="numeric"></label>
<label>Electricity price (pence per kWh)<input id="bd-arc-rate" type="number" min="0" step="0.01" value="26.32" inputmode="decimal"><span class="hint" id="bd-arc-ratehint"></span></label>
</div>
</fieldset>

<div class="result" aria-live="polite">
<p class="big" id="bd-arc-big"></p>
<table class="res"><tbody>
<tr><td>Energy used per hour switched on</td><td id="bd-arc-kwh"></td></tr>
<tr><td>Cost per hour</td><td id="bd-arc-hour"></td></tr>
<tr><td>Cost per day of use</td><td id="bd-arc-day"></td></tr>
<tr><td>Cost per week</td><td id="bd-arc-week"></td></tr>
<tr><td>Cost per month</td><td id="bd-arc-month"></td></tr>
</tbody></table>
<p class="note">This is the extra cost of running the appliance. It does not change your daily standing charge.</p>
<details><summary>Show the working</summary><pre id="bd-arc-working"></pre></details>
</div>

<div class="result" style="margin-top:14px">
<p style="font-weight:700;margin:0 0 4px">Compared at the same hours and price</p>
<table class="cmp"><thead><tr><th>Appliance (full power)</th><th>Per hour</th><th>Per month</th></tr></thead><tbody id="bd-arc-cmp"></tbody></table>
</div>

<p class="bd-credit" style="font-size:.85em;opacity:.75;margin:10px 0 0">Appliance running cost calculator by <a href="https://braindumps.co.uk/appliance-running-cost-calculator/">Braindumps.co.uk</a></p>
<script>
(function () {
  "use strict";
  /* BEGIN CALC */
  var RATE = { p: 26.32, label: "Ofgem price cap for England, Scotland and Wales, 1 October to 31 December 2026 (Direct Debit, average, no VAT on electricity)." };
  var APPLIANCES = [
    { id: "fan", name: "Fan heater, 2 kW", w: 2000 },
    { id: "oil", name: "Oil-filled radiator, 2 kW", w: 2000 },
    { id: "conv", name: "Convector heater, 2 kW", w: 2000 },
    { id: "small", name: "Small heater, 1 kW", w: 1000 },
    { id: "dehc", name: "Dehumidifier, compressor (small to medium)", w: 300 },
    { id: "dehd", name: "Dehumidifier, desiccant", w: 500 },
    { id: "blks", name: "Electric blanket, single", w: 80 },
    { id: "blkd", name: "Electric blanket, double", w: 150 },
    { id: "air", name: "Air fryer, 1.4 kW", w: 1400 },
    { id: "airl", name: "Air fryer, large, 1.8 kW", w: 1800 }
  ];
  function runCost(watts, dutyPct, hoursPerDay, daysPerWeek, pence) {
    if (!(watts >= 0) || !(dutyPct > 0) || !(hoursPerDay >= 0) || !(daysPerWeek >= 0) || !(pence >= 0)) { return null; }
    var kwhPerHour = watts / 1000 * Math.min(dutyPct, 100) / 100;
    var perHour = kwhPerHour * pence / 100;
    var perDay = perHour * hoursPerDay;
    var perWeek = perDay * daysPerWeek;
    var perMonth = perWeek * 52 / 12;
    return { kwhPerHour: kwhPerHour, perHour: perHour, perDay: perDay, perWeek: perWeek, perMonth: perMonth, kwhPerDay: kwhPerHour * hoursPerDay };
  }
  /* END CALC */
  function $(id) { return document.getElementById("bd-arc-" + id); }
  function money(v) { return v < 1 ? (v * 100).toFixed(1) + "p" : "£" + v.toFixed(2); }
  function fixed(v, d) { return v.toFixed(d); }
  var sel = $("app");
  APPLIANCES.forEach(function (a) { var o = document.createElement("option"); o.value = a.id; o.textContent = a.name; sel.appendChild(o); });
  var oc = document.createElement("option"); oc.value = "custom"; oc.textContent = "Other: type the watts"; sel.appendChild(oc);
  $("ratehint").textContent = RATE.label + " Change it to the rate on your bill.";

  function update() {
    var w = parseFloat($("w").value), duty = parseFloat($("duty").value), h = parseFloat($("h").value), d = parseFloat($("d").value), p = parseFloat($("rate").value);
    var r = runCost(w, duty, h, d, p);
    if (!r) {
      $("big").textContent = "Fill in every box with a number.";
      ["kwh", "hour", "day", "week", "month"].forEach(function (k) { $(k).textContent = "–"; });
      $("working").textContent = "";
    } else {
      $("big").textContent = "About " + money(r.perMonth) + " a month";
      $("kwh").textContent = fixed(r.kwhPerHour, 3) + " kWh";
      $("hour").textContent = money(r.perHour);
      $("day").textContent = money(r.perDay);
      $("week").textContent = money(r.perWeek);
      $("month").textContent = money(r.perMonth);
      var L = [];
      L.push("Energy per hour = " + fixed(w, 0) + " W ÷ 1,000 × " + fixed(Math.min(duty, 100), 0) + "% = " + fixed(r.kwhPerHour, 3) + " kWh");
      L.push("Cost per hour   = " + fixed(r.kwhPerHour, 3) + " kWh × " + fixed(p, 2) + "p = " + fixed(r.kwhPerHour * p, 2) + "p");
      L.push("Cost per day    = " + fixed(r.kwhPerHour * p, 2) + "p × " + fixed(h, 1) + " hours = " + money(r.perDay) + " (" + fixed(r.kwhPerDay, 2) + " kWh)");
      L.push("Cost per week   = " + money(r.perDay) + " × " + fixed(d, 0) + " days = " + money(r.perWeek));
      L.push("Cost per month  = " + money(r.perWeek) + " × 52 ÷ 12 = " + money(r.perMonth));
      $("working").textContent = L.join("\n");
    }
    var body = $("cmp");
    body.textContent = "";
    APPLIANCES.forEach(function (a) {
      var c = runCost(a.w, 100, isFinite(h) ? h : 0, isFinite(d) ? d : 0, isFinite(p) ? p : 0);
      if (!c) { return; }
      var tr = document.createElement("tr");
      [a.name, money(c.perHour), money(c.perMonth)].forEach(function (t) { var td = document.createElement("td"); td.textContent = t; tr.appendChild(td); });
      body.appendChild(tr);
    });
  }
  function setApp() {
    var a = APPLIANCES.filter(function (x) { return x.id === sel.value; })[0];
    if (a) { $("w").value = a.w; }
    update();
  }
  sel.addEventListener("change", setApp);
  $("w").addEventListener("input", function () { sel.value = "custom"; update(); });
  ["duty", "h", "d", "rate"].forEach(function (k) { $(k).addEventListener("input", update); });
  sel.value = "fan";
  update();
})();
</script>
</div>