Electricity Cost Calculator | Estimate Monthly Bill by Appliance
Enter each appliance's wattage, usage time, and electricity rate to estimate your monthly electricity bill. Add multiple appliances and see the total cost at a glance.
| Appliance | Wattage (W) | Hours/day | Days/month | Monthly usage | Monthly cost | |
|---|---|---|---|---|---|---|
| [[ fmtKwh(rowResults[i]?.kwhPerMonth) ]] | [[ fmtYen(rowResults[i]?.costPerMonth) ]] yen | |||||
| Total | [[ fmtKwh(total.kwhPerMonth) ]] | [[ fmtYen(total.costPerMonth) ]] yen | ||||
Typical Appliance Power Usage & Cost (at 31 yen/kWh)
| Appliance | Typical wattage | Estimated cost per hour |
|---|---|---|
| Air Conditioner (Cooling) | 800 W | 25 yen |
| Air Conditioner (Heating) | 1,200 W | 37 yen |
| Refrigerator | 150 W | 5 yen |
| Washer-Dryer | 1,200 W | 37 yen |
| Microwave Oven | 600 W | 19 yen |
| IH Cooktop | 1,400 W | 43 yen |
| Rice Cooker (while cooking) | 700 W | 22 yen |
| Hair Dryer | 1,200 W | 37 yen |
| TV (40-inch LCD) | 150 W | 5 yen |
| Desktop PC | 150 W | 5 yen |
| LED Light (1 fixture) | 10 W | 0 yen |
| Electric Kettle | 1,300 W | 40 yen |
Wattage figures are typical estimates for common models. Actual power consumption varies by model, settings, and usage conditions. Check the product's rated power consumption for exact values.
What Is an Electricity Cost Calculator?
An electricity cost calculator estimates the monthly energy consumption (kWh) and cost of each appliance from its wattage (W), daily usage time, the number of days used per month, and your electricity rate (per kWh). As you add appliances such as an air conditioner, refrigerator, or washer-dryer, the tool shows a breakdown for each one alongside a running total for the whole household — no need to reach for a calculator or spreadsheet.
The underlying formula is simple: wattage (W) × hours per day × days per month ÷ 1000 × electricity rate. Dividing by 1000 converts watt-hours into kilowatt-hours (kWh), which is the unit almost every utility bill is priced in, so the result lines up closely with what you would see on your actual statement. Keep in mind that a real bill usually adds a fixed base charge and other surcharges on top of pure energy usage, so treat the figure here as a usage-based estimate rather than a guaranteed final total.
How to Use the Electricity Cost Calculator
- Enter your electricity rate Enter the price per kWh shown on your latest bill or your provider's rate plan page. If you don't know the exact figure, you can leave the default estimate in place and still get a useful comparison.
- Add an appliance and give it a name Type a name such as "Air Conditioner" or "Refrigerator" into the appliance field. Add a new row for each additional appliance you want to include in the estimate.
- Enter wattage, hours per day, and days per month Fill in the appliance's wattage (W), how many hours a day it runs, and how many days a month it's used. The reference table further down the page lists typical wattage for common appliances if you're unsure of the exact figure.
- Add as many appliances as you need Repeat the same steps for every appliance you want to track, and the monthly cost for each one is calculated automatically as you go.
- Check the household total in the totals row The totals row at the bottom of the list adds up the monthly energy usage and cost across every appliance you've entered, giving you a single household-wide estimate.
Tips for getting more out of it
- Electricity rates vary by utility company, plan, and region. Enter the rate shown on your latest billing statement for a more accurate estimate.
- Air conditioner power draw fluctuates a lot with the set temperature and outdoor temperature, so treat this calculation as an average estimate only.
- Add multiple appliances to see your household's estimated total monthly electricity cost in the total row.
- Standby power (drawn just by being plugged in) can add up over time, so it's worth using a switched power strip to fully cut power to unused appliances.
When This Calculator Is Useful
Forecasting summer air conditioning costs early
Before the hottest weeks of summer push up your usage time, try different set temperatures and run times to see how far your air conditioning bill could climb.
Comparing a time-of-use rate plan
Swap in the off-peak rate from a time-of-use plan to see roughly how much you could save by shifting usage to cheaper hours, before committing to switch plans.
Putting a number on standby power
Enter the standby wattage of an always-on device like a router or refrigerator together with 24 hours of daily use to see exactly how much idle power is costing you each month.
Comparing running costs before buying a new appliance
Enter the wattage listed on a new appliance's spec sheet to estimate its monthly running cost before you buy it, so you can weigh energy efficiency against the sticker price.
Comparing bills for different household sizes
Try a few scenarios with different numbers of appliances and usage times to get a feel for how electricity costs typically differ between a single-person household and a larger family home.
Glossary
- kWh (kilowatt-hour)
- The standard unit of energy consumption used on electricity bills. It represents the energy used by running a 1 kW load for one hour, and your bill is calculated by multiplying your total kWh usage by your rate per kWh.
- W (watt)
- The unit of power that measures how much energy an appliance draws at any given moment. This is the "rated power consumption" figure printed on a product's spec label or nameplate.
- Electricity rate
- The price charged per kWh of electricity used. The rate depends on your utility provider, the plan you're enrolled in, and sometimes how much electricity you use in a billing period.
- Tiered rate plan
- A common billing structure in which the price per kWh increases in steps once your usage passes certain thresholds within a billing period. The more you use, the higher your average rate tends to be.
- Standby power
- The electricity an appliance keeps drawing simply from being plugged in, even when it's switched off. It sounds small per device, but it adds up to a noticeable cost when many devices are involved.
- Fuel cost adjustment
- A charge added to or subtracted from your bill to reflect changes in the wholesale cost of the fuel (such as crude oil, natural gas, or coal) used to generate electricity. It's billed separately from the base charge and standard energy rate.
- Renewable energy surcharge
- A charge added to electricity bills in many countries to help fund the growth of renewable energy sources such as solar and wind. It's typically billed per kWh used and revised periodically.
Frequently Asked Questions
Side Note — The Surprising Ranking of Costly Home Appliances
When people think of a high electricity bill, air conditioners are usually the first suspect. But since a refrigerator runs continuously all year round, its annual energy consumption can rival that of an air conditioner. Because it's "always on," its instantaneous wattage is small, yet the monthly and yearly total becomes surprisingly significant.
On the other hand, appliances like electric kettles and hair dryers draw a very high instantaneous wattage (1,200–1,400W class), but because they're only used for short bursts, their impact on the monthly bill is often smaller than expected. Understanding your real electricity usage requires multiplying wattage by both usage time and frequency, not just looking at the wattage number alone.
Many utility companies now offer time-of-use plans with rates that vary by time of day. Running short, high-wattage appliances like kettles or washer-dryers during off-peak hours can lower your bill for the same amount of usage. Try adjusting the rate in this tool to explore how different plans might affect your total.