Free calculator
Heating element resistance calculator
Enter your element's voltage and rated wattage to get the resistance it should read and the current it draws. Already measured it? Add your reading to see whether it is still in spec.
240, 208 or 120 for most equipment. Take it from the data plate.
From the rating plate or the element's own stamp.
Power off, at least one lead disconnected.
- Current draw
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- Your reading
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- Deviation
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Enter a voltage and rated wattage to calculate the target resistance.
Measure safely
Always kill power at the breaker and disconnect at least one element lead before measuring. Testing in circuit reads everything wired in parallel and gives a meaningless result. If you are not confident working inside the equipment, this is a job for a licensed technician.
The formula
A heating element is a fixed resistance. Resistance, voltage and power are tied together by Ohm's law and the power equation, so knowing any two gives you the rest:
Worked example. An element rated 2,500 W on a 240 V supply should read about 240² ÷ 2,500 = 23.0 Ω, and draw 2,500 ÷ 240 ≈ 10.4 A.
Is my element still good?
Element wire does not fail all at once. As it oxidises and ages, its cross-section thins and resistance creeps up — so it draws less current, makes less heat, and firings get slower until the equipment finally stalls short of temperature. Comparing a measured resistance against the target is the quickest way to catch that:
- Within ~5% Healthy. Keep using it.
- 5–11% high Ageing. Output is dropping and runs will lengthen. Order a set so you are not caught mid-project.
- Over ~11% high, or open Replace it.
These bands are a practical field rule of thumb, not a substitute for your manufacturer's specification. Measure with the power off and the leads disconnected, and in a multi-element setup compare every element — a single odd reading points at the one that has gone.
Questions about testing elements
Does a cold multimeter reading really tell me anything?
For Kanthal and other FeCrAl wire, yes. That alloy has a very small temperature coefficient of resistance, meaning its resistance barely changes between room temperature and full operating heat. A cold reading therefore sits very close to the operating value and can be compared directly against the target. Nichrome behaves similarly enough for this test to be useful too.
Why does resistance go up as an element ages?
Heating element wire does not fail all at once. As it oxidises, the cross-section of the wire thins. A thinner conductor has higher resistance, and higher resistance means less current, which means less heat. That is why firings get gradually longer well before an element actually breaks — the wire is thinning long before it snaps.
My reading is infinite or shows OL. What does that mean?
An open circuit — the wire has burned through somewhere. There is no partial diagnosis to make here; the element is finished and needs replacing. In a multi-element kiln or a staged heat kit, check the others too, because they have the same hours on them.
One element reads differently from the rest. Is that the problem?
Very likely, yes. In a multi-element setup, comparing elements against each other is often more revealing than comparing against the target. They have all done the same work, so one odd reading points straight at the element that has gone.
Should I test with the equipment connected?
No. Kill the power at the breaker and disconnect at least one lead from the element before measuring. Testing in circuit reads whatever else is wired in parallel and gives you a meaningless number — and working on a live heating circuit is genuinely dangerous.
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Reading says replace?
Send us your model and the numbers you measured. We wind the replacement to the resistance your equipment was designed around.