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CalcIntel

Updated · Methodology: named formula library

Electricity Cost Calculator

Calculate how much it costs to run an appliance based on wattage, usage hours, and electricity rate.

Monthly Electricity Cost
$2

Running a 100W appliance 4 hours/day costs approximately $2/month at $0.13/kWh.

Daily Usage0.4 kWh
Monthly Cost$2
Annual Cost$19
Rate$0.13/kWh
Data sources: CalcIntel Formula Library

Why This Calculation Matters

The Electricity Cost Calculator answers a common everyday math question in seconds, no spreadsheet, no mental arithmetic, no sticky notes.

How to Use This Calculator

  • Enter your values in the input fields, each one has a label and help text explaining what to type.
  • Results appear instantly as you type; there's no "calculate" button to press.
  • Change any input to compare scenarios side by side.

All math happens in your browser. Nothing you type is sent to a server, saved, or shared.

Calculating Electricity Cost

Cost = (Watts × Hours × Rate) / 1000

Where rate is in $/kWh (check your utility bill, US average is about $0.12-0.16/kWh).

Common Appliance Costs

  • Space heater (1,500W, 8 hrs): ~$1.44/day
  • Refrigerator (150W, 24 hrs): ~$0.43/day
  • LED bulb (10W, 8 hrs): ~$0.01/day
  • Gaming PC (500W, 4 hrs): ~$0.24/day
  • EV charger (7,200W, 8 hrs): ~$6.91/day

Formula

Cost = kWh × rate. kWh = watts × hours ÷ 1000. National average U.S. residential rate is ~$0.16/kWh (2025), but ranges from ~$0.11 (WA) to ~$0.44 (HI).

Worked Example

100W device, 4 hr/day, 30 days, $0.13/kWh

watts
100
hoursPerDay
4
days
30
rate
0.13
Result
$1.56/month

100W × 4hr × 30 / 1000 = 12 kWh × 0.13 = $1.56.

When to Use This Calculator

  • Answer a quick "how much / how many" question without pulling out a spreadsheet.
  • Sanity-check a bill, a quote, or a receipt in seconds.
  • Compare options side by side before committing.

Limitations & Common Mistakes

  • Results are estimates, real-world outcomes depend on factors not captured in a simplified calculation.
  • Always verify critical numbers against an authoritative source or domain expert before acting on them.

Frequently Asked Questions

How does the Electricity Cost Calculator work?

Enter your wattage (w) (default: 100) and any other inputs; the calculator instantly applies its electricity cost formula and shows the result with details. All math runs in your browser; nothing is sent to a server.

Is the Electricity Cost Calculator accurate for utilities decisions?

It uses standard, documented formulas that match published references. For high-stakes utilities decisions, verify the result against an authoritative source (industry calculator, professional advisor, or government data). The calculator is a planning estimate, not a substitute for professional judgment.

What inputs does the Electricity Cost Calculator require?

3 inputs: Wattage (W), Hours Per Day, Rate ($/kWh). Each has a sensible default; replace with your own values to get a result tailored to your situation.

Can I bookmark or share the Electricity Cost Calculator?

Yes — the URL is stable: https://www.calcintel.com/calculator/electricity-cost. Inputs reset to defaults on each visit (no input is stored), so screenshot or copy the result if you want to preserve a specific scenario.

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Key terms

Source: BLS Consumer Price Index, 2026.