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Use the calculator for an instant estimate, or read on for a full breakdown of how this cost is calculated.
Examples and calculation text checked September 22, 2026. This is a planning guide, not an individual engineering review.
Illustrative example
$144/year
Declared inputs, not a typical-home range
1,500 watts ÷ 1,000 × 4 hours/day × 120 days = 720 kWh/year, costing $144 at $0.20/kWh. One hour at full power costs $0.30; a 30-day month at 4 hours/day costs $36.
Use the selected power setting. If the thermostat switches the heater off part of the time, count the equivalent hours drawing that power rather than assuming every plugged-in hour is a heating hour.
This is the added heater's electricity cost. Whether it reduces whole-home cost depends on what other heating it replaces and how that system operates; this calculation does not assume those savings.
The calculator starts with the same example. Its $12 average-month cost is annual cost divided by 12; seasonal bills can look very different. The $0.20/kWh rate is illustrative, not a national average. Use your energy rate; fixed fees and taxes are separate.
The starting values are an example. Replace them with your equipment and usage.
Hours mean time drawing the stated power. A thermostat may cycle the heater off, so clock time alone can overstate consumption.
720 kWh per year
$144.00 per year
$12.00 per average month (annual cost ÷ 12)
Energy charges only. Fixed fees, taxes, tiered and time-of-use billing are excluded. The average month is not a seasonal forecast.
Power setting in watts
Actual or estimated duty cycle
Operating days during the heating season
Whether another system's use changes
Before making a change
Check the large loads and uncertain assumptions first. Compare a specific change against your existing equipment before deciding whether an upgrade is worth investigating.
These sources explain units and equipment labels. The worked household values are illustrative inputs, not measured customer data or published typical-use ranges.
Follow the free walkthrough to build a household electricity estimate, review its assumptions and compare changes. The optional $19 purchase unlocks both dated PDF report formats for your household profile.
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