100 W TV for 4 hours/day
100 W x 4 hours / 1000 = 0.4 kWh/day. At $0.17/kWh, that is about $0.07/day or $24.82/year.
Electricity Usage Calculator — Home Energy Cost & kWh
Use this home energy usage calculator to estimate kWh per day, month, and year.
Enter appliance power, running time, cycle energy, or label data to estimate electricity cost and each appliance's impact on your bill.
Household & Tariff
Appliances
Tip: For cycling appliances such as refrigerators or AC units, use average running watts or the annual kWh label when you have it. Rated watts can be higher than typical draw.
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How This Electricity Usage Calculator Works
This electricity usage calculator helps you estimate where your power goes and how much it costs. By adding appliances and entering how often you use them, you get daily, monthly, and yearly kWh totals, estimated bill impact, annual CO₂, standby load, and a ranked appliance breakdown.
The math is simple. Each device uses power over time. The calculator converts label units such as watts, kW, BTU/h, horsepower, and tons of refrigeration into watts, converts your usage schedule into annual hours, and then sums each appliance.
To use the calculator, follow these steps:
- Add appliances using presets or create custom entries for the devices in your home.
- Choose a time-based input, cycle-based input, or heat-pump heat/COP input.
- Enter the power and usage units that match your appliance label or routine.
- Pick a region default, or set your own electricity price and grid emissions factor.
- Review per-day, per-month, and per-year kWh and cost, plus the biggest savings opportunities.
kWh/day = watts × hours/day ÷ 1000
cost/day = kWh/day × price/kWh
annual kWh = daily kWh × active days/year
standby kWh = standby watts × standby hours × days ÷ 1000
CO₂ = kWh × kg CO₂/kWh
Worked Examples
Refrigerator electricity per month
A refrigerator averaging 60 W over 24 hours uses 1.44 kWh/day, or about 43 kWh/month. Use the annual kWh label when available.
LED vs incandescent bulb
A 9 W LED used 3 hours/day uses about 9.9 kWh/year. A 60 W incandescent on the same schedule uses about 65.7 kWh/year.
Space heater for 6 hours/day
A 1500 W heater used 6 hours/day uses 9 kWh/day. At $0.17/kWh, that is about $1.53/day.
Common Appliance Wattage and kWh Table
| Appliance | Typical watts | Typical use pattern | Estimated kWh/month | Notes |
|---|---|---|---|---|
| Refrigerator / freezer | 40-200 W average | 24 hours/day | 30-70 | Label annual kWh is usually better than rated watts. |
| Central AC | 2500-5000 W input | 4 hours/day in cooling months | 300-600 | Compressor cycling and climate matter heavily. |
| Window AC | 500-1500 W | 6 hours/day in cooling months | 90-270 | BTU/h is cooling capacity, not always electrical input. |
| Space heater | 750-1500 W | 4 hours/day | 90-180 | Resistance heat is usually one of the highest-cost loads. |
| Electric water heater | 3500-5500 W | 1-3 hours/day equivalent | 105-495 | Use EnergyGuide annual kWh when available. |
| Clothes dryer | 2-4 kWh/cycle | 12 cycles/month | 24-48 | Cycle labels are easier than wattage for dryers. |
| Dishwasher | 0.8-1.8 kWh/cycle | 20 cycles/month | 16-36 | Heated dry can raise energy use. |
| LED bulb | 6-12 W | 3 hours/day | 0.5-1.1 each | Multiply by number of bulbs. |
| TV | 50-200 W | 4 hours/day | 6-24 | Screen size and brightness change draw. |
| Wi-Fi router | 8-15 W | 24 hours/day | 6-11 | Always-on electronics are small but continuous. |
| EV charger | 1400-9600 W | Vehicle miles determine use | 150-500+ | Estimate from miles, efficiency, and charging losses when possible. |
How to Use Energy Labels
If your appliance has an EnergyGuide, ENERGY STAR, EnerGuide, or manufacturer label, use the most direct energy number available before falling back to rated watts.
- Annual kWh label: divide the annual kWh by 52 and enter it as a cycle item with 1 cycle/week, or enter the annual value as a custom comparison outside the appliance presets.
- kWh/cycle label: choose cycle mode and enter kWh per cycle plus your usual cycles per week.
- Rated watts label: use time mode, but remember that rated watts can be peak draw. For cycling devices, average running watts or label kWh is usually closer.
- BTU/h, horsepower, or tons: these describe equipment size or output. Use the unit selector for a rough conversion, but use measured input watts when the label provides it.
Methodology and Sources
- Regional tariff defaults are broad planning estimates, not live utility rates. Check your bill for the actual price per kWh, delivery charges, taxes, and time-of-use rules.
- Grid intensity defaults are approximate country or region factors for comparing CO₂ impact. Local supplier mix can differ substantially.
- Appliance wattage ranges are compiled from common manufacturer labels, energy labels, and typical household calculator assumptions.
- All calculations run in your browser. Appliance names and usage values are not uploaded.
FAQs
How do I calculate kWh from watts?
Multiply watts by hours of use, then divide by 1000. A 100 W appliance used for 4 hours uses 0.4 kWh.
How much does it cost to run an appliance?
Multiply kWh by your electricity price per kWh. For example, 0.4 kWh at $0.17/kWh costs about $0.07.
How many kWh does a refrigerator use?
Many refrigerators use roughly 30 to 70 kWh per month. Use the EnergyGuide, EnerGuide, or manufacturer annual kWh label when you have it.
What appliances use the most electricity?
Heating, cooling, water heating, dryers, ovens, dehumidifiers, and EV charging often use the most electricity, but your climate and habits can change the ranking.
Should I use rated watts or average watts?
Use average running watts when available. Rated watts can overstate cycling appliances such as refrigerators, AC units, heat pumps, and dehumidifiers.
How do I calculate standby power?
Standby kWh = standby watts × standby hours × days ÷ 1000. Enter standby watts and standby hours/day in the advanced fields.
How do I find my electricity price per kWh?
Look at your utility bill for the energy charge per kWh. Include delivery charges if you want the calculator to estimate full bill impact.
Why is my actual bill different?
Actual bills can differ because of fixed charges, taxes, tiered rates, time-of-use tariffs, weather, appliance cycling, and behavior changes.
What if I only know annual kWh from the label?
Add a custom item and switch to the cycle mode using 1 cycle/week with kWh/cycle = annual kWh / 52, or use the time mode with hours and watts that match the label.
How do I include standby?
Use the standby watts field and set the hours/day it is in standby. Standby is added on top of active use.
Can I change the currency?
Yes. Pick a region default or set the currency symbol manually. Tariff is per kWh in that currency.