Electricity Cost Calculator

Electricity Cost Calculator

Calculate daily, monthly, and yearly electricity costs for your appliances and devices. Understand and reduce your energy expenses.

Last updated: March 2026 | By Patchworkr Team

Appliance Usage

Power consumption (check appliance label or manual)

Average daily usage (0-24 hours)

Check your electricity bill. Rates vary by region and utility (residential US: typically $0.10–$0.16/kWh, but local rates may differ)

Understanding Electricity Costs

Electricity is billed in kilowatt-hours (kWh). One kWh is the energy used by a 1000-watt appliance running for one hour. For example, a 100W light bulb running for 10 hours uses 1 kWh (100W × 10h = 1000 Wh = 1 kWh).

Your electricity rate varies by location, time of day, and provider. The US average is around $0.12/kWh, but rates range from $0.08/kWh in some states to $0.30+/kWh in others. Check your electricity bill for your exact rate - it's usually shown as "Price per kWh" or "Rate per kWh."

Understanding electricity costs helps identify energy hogs in your home. A space heater running 8 hours daily costs significantly more than a laptop running the same time. Small changes like switching to LED bulbs or adjusting thermostat settings can substantially reduce your monthly bill.

The Formula

Energy Consumption

kWh = (Watts × Hours) / 1000
Where:
• Watts = power consumption
• Hours = usage time per day
• Divide by 1000 to convert Wh to kWh

Cost Calculation

Cost = kWh × Rate
Where:
• kWh = energy consumed
• Rate = price per kWh (from your bill)
• Multiply by 30 for monthly, 365 for yearly

Example Calculation

1500W space heater running 8 hours/day at $0.12/kWh:

Step 1:
Calculate daily kWh:
(1500W × 8h) / 1000 = 12 kWh/day
Step 2:
Calculate daily cost:
12 kWh × $0.12/kWh = $1.44/day
Step 3:
Calculate monthly and yearly:
Monthly: $1.44 × 30 = $43.20
Yearly: $1.44 × 365 = $525.60
Result:
$43.20/month
Running this heater for winter months (4-5 months) = $170-215/year

Frequently Asked Questions

Where do I find my electricity rate?

Check your monthly electricity bill - look for "Price per kWh" or "Rate." It's usually between $0.08-0.30/kWh depending on location. Some areas have time-of-use rates (higher during peak hours).

How much do common appliances cost to run?

LED bulb (10W): ~$1/year. Laptop (65W): ~$10/year. Desktop PC (300W): ~$40/year. Refrigerator (150W avg): ~$150/year. AC unit (3500W): ~$300-600/season. Space heater (1500W): ~$40/month.

What uses the most electricity?

Heating/cooling (HVAC) typically accounts for 45% of home energy. Water heater: 14%. Washing machine/dryer: 13%. Lighting: 9%. Refrigerator: 4%. Small appliances and electronics make up the rest.

Can I reduce my electricity bill?

Yes! Switch to LED bulbs (75% less energy), adjust thermostat by 2°F (10% savings), use ceiling fans, unplug phantom loads, wash clothes in cold water, air-dry when possible, and maintain HVAC systems regularly.

Do devices use power when off?

Yes, "phantom" or "vampire" loads consume 5-10% of home energy. TVs, chargers, computers, and appliances in standby mode still draw power. Use power strips and turn them off to eliminate phantom loads.

Are energy-efficient appliances worth it?

Usually yes. An Energy Star refrigerator saves ~$35/year. LED bulbs save $8/year each vs incandescent. Calculate payback time: (Extra Cost) / (Annual Savings). Typical payback is 2-5 years with 10-20 year product life.

How accurate is this calculator?

Very accurate for constant-load devices (heaters, lights). Less accurate for variable loads (refrigerators cycle on/off). Actual costs vary with usage patterns, rates, and efficiency. Use this as an estimate.

What if my rate varies by time of day?

Time-of-use rates charge more during peak hours (4-9 PM). Calculate costs separately for peak/off-peak hours. Shift usage to off-peak when possible - run dishwasher/laundry at night for significant savings.

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