Calculation details
Energy-cost estimate only. Verify your utility tariff, taxes, time-of-use pricing, equipment efficiency, and manufacturer specifications before relying on the result.
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Use this result
Share the current inputs or ask ChatGPT to explain the calculation in context.
What does this calculator estimate?
A 1,500-watt appliance used 4 hours per day for 30 active days at $0.20 per kWh uses 180 kWh and costs $36 for the month, about $432 per year. Monthly kWh = watts / 1,000 x hours per day x active days per month.
- Monthly kWh = watts / 1,000 x hours per day x active days per month (EIA).
- Cost = kWh x electricity rate; the same schedule over 12 months gives the annual cost.
- The average US residential rate was about 16 cents per kWh in 2025.
How appliance costs are estimated
Electricity is billed per kilowatt-hour — 1,000 watts running for an hour. Converting an appliance's wattage and usage into kWh, then multiplying by your rate, gives the running cost. The calculator does this for any device.
Limitations to watch for
The estimate assumes constant wattage — appliances with compressors (fridges, AC) cycle on and off, so use average watts. Your actual rate may have tiers, time-of-use pricing, and fixed fees. Phantom loads (standby) draw power even when 'off'.
How to use it in practice
Check the wattage on the device label or plug, estimate daily hours, and enter your rate (on the bill). Compare devices to find the big consumers. Kill standby loads to cut the hidden 5–10% of usage.
['Enter the device wattage.', 'Enter the hours per day and your rate per kWh.', 'Read daily, monthly, and yearly costs.']
How electricity cost is calculated
Cost = watts × hours ÷ 1,000 × rate: a 100 W bulb for 10 hours at $0.15/kWh costs $0.15 daily. The calculator converts appliance wattage and usage into daily, monthly, and yearly cost.
The kilowatt-hour
Electricity is billed per kilowatt-hour: 1,000 watts for one hour. A 1,500 W heater for 8 hours uses 12 kWh — at $0.15/kWh, $1.80 per day, about $650 per year. The calculator makes the hidden cost visible.
Big loads, big savings
HVAC, water heating, laundry, and space heaters dominate bills. A 3,500 W AC for 6 hours daily costs $3.15 per day at $0.15/kWh. Targeting the biggest loads first is the efficient path to lower bills.
A worked example
A gaming PC at 400 W for 4 hours daily: 1.6 kWh/day, $0.24/day, about $87 per year. The calculator runs any appliance's math from its label wattage.
Comparing appliances
Efficiency labels quote annual kWh — multiply by your rate for the annual cost: a 350 kWh fridge at $0.15 costs $52.50 yearly. The calculator turns label numbers into dollars.
How this calculator works
Formula
Energy (kWh) = power (watts) × hours used ÷ 1,000. Cost = kWh × electricity rate. The tool can compare multiple devices.
Worked example
A 100 W device running 10 hours uses 1 kWh/day — at $0.15/kWh that's $0.15 per day, about $4.50/month.
Assumptions to verify
- The device runs at its rated wattage.
- The rate is constant across the period.
- Usage is consistent daily.
Frequently asked questions
How do I calculate electricity cost?
kWh = watts × hours ÷ 1,000, then × rate. A 100 W device for 10 h = 1 kWh = $0.15 at $0.15/kWh.
What is a kilowatt-hour?
1,000 watts running for 1 hour — the unit utilities bill.
How do I find my electricity rate?
It's on your bill — total charges divided by kWh used, or the listed rate (usually $0.10–$0.30).
Why is my appliance costing more than estimated?
Compressors cycle, rates have tiers, and standby draws add hidden usage.
What appliances cost the most?
Heating/cooling, water heaters, dryers, and ovens — anything that heats or cools.
How do I reduce the bill?
Cut standby loads, use energy-efficient devices, shift use off-peak if your rate varies.
Does this include fixed fees?
No — it's the energy charge only; delivery and fixed fees are on top.
How do I calculate appliance cost?
Watts × hours ÷ 1,000 × rate per kWh.
What uses the most electricity?
Heating/cooling, water heating, laundry, and major appliances.
How do I use the efficiency label?
Multiply the annual kWh by your rate: 350 kWh × $0.15 = $52.50/year.
Cite this tool
BoringToolsKit. “Electricity Cost Calculator.” boringtoolskit.com/electricity-cost-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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