Cost per hour, day and month
The table holds power and price constant so you can see the effect of runtime. The hours are scenarios, not recommended use or measured household habits.
| Hours per day | kWh per day | Cost per day | kWh per month | Cost per month |
|---|---|---|---|---|
| 1 | 1.5 | $0.30 | 45 | $9.00 |
| 4 | 6 | $1.20 | 180 | $36.00 |
| 8 | 12 | $2.40 | 360 | $72.00 |
The eight-hour row is a cost calculation, not advice to leave a heater running while you sleep. CPSC says to turn portable electric heaters off when sleeping or leaving them unattended. Follow your heater's instructions.
Reference: EIA: Measuring electricity · CPSC: Portable electric heater safety alert
Calculate your own electricity cost
Watts describe electrical power. Kilowatt-hours describe energy consumed over time: 1,000 watts equals one kilowatt, and one kilowatt used for one hour equals one kilowatt-hour.
For constant power: kWh = watts ÷ 1,000 × operating hours. Energy cost = kWh × electricity rate in dollars per kWh.
For the eight-hour example: 1,500 ÷ 1,000 = 1.5 kW; 1.5 × 8 = 12 kWh; 12 × $0.20 = $2.40. Repeating that use for 30 days gives $72. Keep unrounded values through the calculation and round the final cost to cents.
Reference: EIA: Measuring electricity · RealCostTools: Appliance electricity methodology
Find the wattage for your model and setting
Check the heater's rating label and manufacturer documentation. Use electrical input power, rather than a room-size claim or a heat-output figure in BTU.
The 1,500 W example is not a market average. Vornado documents 1,500 W high and 750 W low settings for its VH10, while some smaller models have lower ratings. Settings vary by model.
At the illustrative 20¢ rate, a constant 750 W draw costs $0.15 per hour. That is half the cost of a constant 1,500 W draw over the same hour; it does not establish that the lower setting will achieve the same comfort in the same time.
Reference: Vornado: Heater FAQs
Use the rate that applies to the extra electricity
For a flat-rate plan, identify the charges on your bill that vary with kWh, including applicable supply and delivery charges. Keep fixed monthly charges separate. Dividing the entire bill by total kWh can spread fixed charges across usage and misprice an additional appliance.
If your plan has time-of-use prices or usage tiers, calculate each portion of the heater's consumption at the rate that applies to it, then add the costs. The calculator applies one entered rate to the modeled load.
If you do not have your bill, the calculator offers dated EIA state benchmarks as a starting point. A state average is not your utility tariff. The 20¢ rate in this guide is illustrative; it is not presented as a national or state average.
Find and interpret the electricity rate on your bill ↗
Reference: RealCostTools: Appliance electricity methodology · RealCostTools: Electricity rates and bill guidance
Switched-on time can differ from time at full power
Heater controls work differently. Vornado describes its VH10 switching heat and fan off at the selected temperature, then restarting as the room cools. Its AVH10 can reduce wattage and fan speed instead.
For a heater that cycles, estimate time drawing the selected power rather than automatically counting the entire period it is enabled. For a model that varies its draw, an observed average power over the period or measured energy is more informative than assuming maximum wattage throughout.
Do not apply a universal percentage discount for thermostat cycling. If you lack measurements, label the result as a constant-power scenario and compare a shorter runtime to see how sensitive the estimate is. That comparison does not predict your heater's cycling.
If you want to measure consumption, ask the manufacturer or your utility for a method compatible with your heater and follow its instructions. Do not assume an inline smart plug or timer is suitable.
Reference: Vornado: Heater FAQs
Do ceramic, oil-filled and infrared heaters cost different amounts?
At the same actual electrical power, runtime and electricity rate, the calculated electricity cost is the same. A heater drawing 1.5 kW for one hour uses 1.5 kWh regardless of its marketing category.
That does not mean different models provide identical comfort or consume identical energy over an evening. Controls and heat delivery differ. Compare the electrical energy used over the period you care about, rather than assuming one heater category is automatically cheaper.
Reference: EIA: Measuring electricity · Vornado: Heater FAQs · Mason County PUD 3: Space heater explanation
Use the calculator with your numbers
Choose wattage and hours, enter your model's wattage, set hours and operating days, and use quantity one for one heater. The electricity-rate field uses cents/kWh: enter 20 for $0.20/kWh. Leave the optional alternative annual kWh blank for this example.
| Item | Example result |
|---|---|
| Monthly electricity | 360 kWh |
| Monthly electricity cost | $72.00 |
| Annual cost if repeated for twelve identical months | $864.00 |
The annual result repeats the monthly schedule twelve times. It is not a prediction of winter usage or a heating-season total.
Illustrative figures, not market averages. The underlying costs are calculated with the same engine as the tool; additional derived measures are labeled.
Calculate my heater cost ↗Keep a heating-season budget separate from the annual result
For a seasonal budget, calculate only the days you expect to use the heater. If runtime or rates change between months, calculate those months separately and add them. For illustration, four identical $72 months total $288; four months is an assumption, not a typical heating season.
The calculator repeats a monthly schedule twelve times for annual results: 30 days per month becomes 360 operating days. Its weekly schedule uses a different convention, 365.2425 ÷ 7 weeks per year. Neither option predicts your local heating season.
This estimates the heater's electricity charge. It does not establish savings against central heating: that requires a separate comparison of the heat displaced, heating system, fuel prices, efficiency and conditions. The present calculator does not model that comparison.
Prepared by RealCostTools with AI-assisted research and drafting. Sources and the stated calculator example were checked September 15, 2026. These examples are calculations, not laboratory measurements of a heater.
Sources and calculation notes
- EIA: Measuring electricity
Undated reference, checked September 15, 2026. Power and energy units; no household usage average taken from this source.
- CPSC: Portable electric heater safety alert
Publication 098, checked September 15, 2026. Sleeping and unattended-use guidance. Historical fire statistics are not used here.
- RealCostTools: Appliance electricity methodology
Live model and implementation checked September 15, 2026. Monthly and annual conventions; example costs use the calculator engine.
- Vornado: Heater FAQs
Undated manufacturer documentation checked September 15, 2026. VH10 settings and cycling; AVH10 variable-power controls. Model examples, not market averages or product endorsements.
- RealCostTools: Electricity rates and bill guidance
Checked September 15, 2026. Consumption-dependent charges, fixed charges, benchmark limits and single-rate model exclusions.
- Mason County PUD 3: Space heater explanation
Undated utility explanation checked September 15, 2026. Equal-power comparison and heat delivery; its broad wattage assumptions are not adopted.
Read the appliance electricity cost methodology for the model assumptions and excluded costs.
Published . Sources checked . Editorial policy · Corrections