CALTRX

Electricity Calculator

Calculate how much any appliance or device costs to run. Enter wattage, hours of use, and your electricity rate for daily, monthly, and annual cost.

Watts
hrs/day
days
$/kWh

Enter your values above to see the results.

Tips & Notes

  • ✓Find your exact electricity rate on your utility bill — look for "energy charge" or "rate per kWh." US rates average $0.13-0.17/kWh but vary from $0.08 (Louisiana) to $0.35+ (Hawaii, California).
  • ✓Your three biggest electricity consumers are almost always heating/cooling (40-50% of bill), water heating (14-18%), and major appliances like dryer and refrigerator (12-15%).
  • ✓Switching from a 60W incandescent to a 9W LED bulb saves 85% in lighting electricity. At $0.15/kWh and 8 hours/day, that is $23.65/year per bulb replaced.
  • ✓Appliances in standby mode still draw power — TVs, game consoles, and chargers typically use 1-5W continuously. A 3W standby load costs about $3.94/year at $0.15/kWh.
  • ✓Running large appliances during off-peak hours (typically 9 PM to 7 AM) can reduce costs by 20-50% if your utility offers time-of-use (TOU) pricing — check your plan.

Common Mistakes

  • ✗Entering kilowatts instead of watts — a 1.5 kW space heater should be entered as 1500W, not 1.5. Check the appliance label for the correct wattage.
  • ✗Leaving the electricity rate at the default or zero — the calculator needs your actual rate. Check your bill for the energy charge per kWh.
  • ✗Using appliance nameplate wattage for cycling appliances — refrigerators, AC units, and heat pumps cycle on and off. Their effective average wattage is 30-50% of nameplate.
  • ✗Estimating hours too loosely — a TV "on all day" may only be actively watched 4 hours. Use actual use time, not time the appliance is available.
  • ✗Comparing appliances at different wattages without checking performance — a 50W LED grow light delivers far less than a 50W incandescent bulb. Wattage measures power draw, not output.

Electricity Calculator Overview

Electricity is typically the second or third largest household expense after housing and food. Understanding the cost to run individual appliances transforms your bill from a mysterious monthly charge into a list of specific choices with known price tags.

Electricity cost formula:

kWh = Watts × Hours ÷ 1000 | Daily Cost = kWh × Rate ($/kWh)
EX: Central AC unit 3,500W running 9 hours/day at $0.14/kWh → kWh/day = 3,500 × 9 / 1000 = 31.5 kWh → Daily cost = 31.5 × $0.14 = $4.41 → Monthly cost = $4.41 × 30 = $132.30
Common household appliances — electricity cost at $0.15/kWh:
ApplianceWattsTypical UseDaily CostMonthly CostAnnual Cost
Central AC3,500W8 hrs/day$4.20$126$1,512
Electric water heater4,000W2.5 hrs/day$1.50$45$548
Electric clothes dryer5,000W1 hr/use × 5/wk$1.07$32$390
Space heater1,500W6 hrs/day$1.35$40.50$493
Refrigerator150W avg24 hrs/day$0.54$16.20$197
Dishwasher1,200W1 hr/day$0.18$5.40$66
55" LED TV80W4 hrs/day$0.048$1.44$17.52
LED bulb10W8 hrs/day$0.012$0.36$4.38
Phone charger5W8 hrs/day$0.006$0.18$2.19
US electricity rates by state — sample (2024 average):
StateAvg Rate ($/kWh)Monthly Bill (1,000 kWh)
Louisiana$0.082$82
Oklahoma$0.091$91
Texas$0.115$115
National Average$0.150$150
California$0.235$235
New York$0.210$210
Hawaii$0.360$360
The biggest lever for reducing electricity costs is always the highest-wattage appliances running the most hours. Heating and cooling (HVAC) account for 40-50% of the average US electricity bill — a programmable thermostat that raises the set point 7-10°F for 8 hours per day while you are away saves approximately 10% annually. Water heating accounts for another 14-18% — a heat pump water heater uses 60-70% less electricity than a standard electric resistance heater and pays back the price premium in 3-5 years. Lighting improvements are highly visible but represent only 5-10% of the average bill. Replacing all incandescent and CFL bulbs with LEDs in a typical home saves $100-200/year — meaningful, but smaller than HVAC and water heating savings. Focus energy-saving efforts where the watts are highest.

Frequently Asked Questions

Multiply the appliance's wattage by daily hours of use, divide by 1000 to get kWh, then multiply by your electricity rate. Example: 1500W space heater running 6 hours/day at $0.15/kWh. Daily kWh = 1500 × 6 / 1000 = 9 kWh. Daily cost = 9 × $0.15 = $1.35. Monthly cost = $1.35 × 30 = $40.50. Annual cost = $1.35 × 365 = $492.75. This is why electric space heaters are expensive to run continuously.

A kilowatt-hour (kWh) is the standard unit of electrical energy billing. One kWh = 1,000 watts running for 1 hour. Your electricity bill shows total kWh consumed in the billing period and the rate per kWh. Example: a 100W bulb running 10 hours uses 1 kWh. A typical US household uses 900-1,100 kWh per month. The energy charge on your bill is your rate × kWh consumed — find the per-kWh rate in the rate schedule or pricing breakdown section.

The biggest electricity consumers in most homes: central air conditioning (3,000-5,000W, running 8-12 hrs/day in summer = $13-25/day at $0.15/kWh); electric water heater (4,000W, 2-3 hrs/day = $1.80-2.70/day); electric clothes dryer (5,000W, 1 hr/cycle = $0.75/load); refrigerator (150W average continuous = $0.54/day); oven (2,500W, 1 hr/use = $0.38/use). Space heaters at 1,500W for 8 hours cost $1.80/day — $54/month if run continuously.

Standby power (also called phantom load or vampire power) adds up across a home. Typical standby draws: smart TV 1-5W, cable box 15-17W (often the worst offender), game console 1-2W in sleep, desktop PC power supply 5-10W, phone charger plugged in but not charging 0.1-0.5W. A cable box at 16W running 24/7 uses 140 kWh/year — about $21 at $0.15/kWh. A smart power strip or smart plug can eliminate standby loads from entertainment center devices with one switch.

The highest-impact actions target the highest-consumption appliances. Raise your AC thermostat 2°F (saves 5-10% on cooling costs). Switch water heater to heat pump type (60-70% more efficient than standard electric). Wash clothes in cold water (90% of washing machine energy goes to heating water). Run dishwasher only when full and use air-dry setting. Replace old refrigerators — a 20-year-old refrigerator uses 3-4× more electricity than a current Energy Star model. Combined, these changes can reduce electricity use by 20-35%.

Time-of-use (TOU) pricing charges different rates for peak hours (typically 4-9 PM weekdays) and off-peak hours. For calculating average daily costs with TOU pricing, use a weighted average rate: (peak hours × peak rate + off-peak hours × off-peak rate) / 24. Example: peak rate $0.35/kWh for 5 hours, off-peak $0.10/kWh for 19 hours → weighted average = (5×0.35 + 19×0.10) / 24 = $0.154/kWh. For appliances you can schedule (dishwasher, EV charging, laundry), use the off-peak rate since you control when they run.