Know what it actually costs before you spend a cent.
Use 55 transparent calculators for appliance costs, solar payback, home heating, EV charging, and backup power. Change the assumptions and see the answer instantly.
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Start with a common energy question
kWh to Watts Calculator
Enter energy used in kilowatt-hours and the time period to calculate the average power in watts and kilowatts.…
Open calculator 02 CoolingHow Much Does a Fan Cost to Run?
A typical 50 W fan running for 8 hours at $0.17/kWh costs about $0.07 per day or $2.04 across 30 days. Enter the…
Open calculator 03 SolarSolar Export Earnings Calculator
When your panels make more than you use, the surplus is exported to the grid for a payment. This calculator esti…
Open calculator 04 Electric VehiclesEV Charging Time Calculator
Estimate how long an EV will take to charge from its battery size, starting percentage, target percentage, charg…
Open calculator 05 ConversionskWh to Wh Calculator
Kilowatt-hours and watt-hours are both units of energy. Enter any value in kWh to convert it directly to Wh; no …
Open calculator 06 ConversionskWh to Amps Calculator
Given how much energy was used (kWh) and over what time, this calculator finds the average current drawn in amps…
Open calculator 07 ConversionsmAh to Wh Calculator & Flight Check
Convert a battery or power bank from mAh to Wh, then compare the result with the FAA passenger-flight battery ba…
Open calculator 08 ConversionsWatts to kWh Calculator
Watts measure power; kilowatt-hours measure energy used over time. Enter a wattage and how long it runs to get t…
Open calculator 09 AppliancesAppliance Running Cost Calculator
Convert representative operating watts and equivalent run time into energy and cost. For cycling or variable-pow…
Open calculatorExplore by the decision you’re making
Solar Panel Costs & Savings
Work through solar sizing, installed cost, savings, export income, payback, and battery value with transparent calculators and decision guidance.
Home Heating & Cooling Costs
Compare heating and cooling running costs, seasonal efficiency, upgrades, and payback with transparent calculators and practical decision guidance.
Electric Vehicle Ownership Costs
Estimate EV charging cost, charging time, and EV-versus-gas ownership economics with transparent calculators and practical decision guidance.
Appliance power & cost data
Compare typical wattage, yearly energy use, and running cost for 38 household appliances.
Best Electricity Usage Monitors (2026): 3 Types Compared
Choose the right way to measure one appliance, automate a plug, or track whole-home and circuit-level electricity use.
Kill A Watt vs Smart Plug: Which Should You Buy?
Choose a simple on-device meter or connected monitoring and schedules based on the appliance and the data you actually need.
All calculators
Browse 55 calculators across 9 practical categories.
No calculators match that search. Try a broader phrase such as “solar”, “fan”, or “watts”.
Solar
6 calculatorsSolar Panel Payback Calculator
Estimate simple solar payback from net installed cost, first-year production and the retail …
Home Battery Payback Calculator
Model one battery cycle as discharged energy that avoids an expensive rate minus the extra c…
Solar System Size Calculator
Convert annual electricity use into a planning-size solar array using local solar resource a…
Solar Savings Calculator
Estimate the value of solar electricity you use at home plus the credit or payment for surpl…
Solar Panel Cost Calculator
Normalize solar quotes by DC system watts, then apply only rebates or credits you have verif…
Solar Export Earnings Calculator
When your panels make more than you use, the surplus is exported to the grid for a payment. …
Heating
9 calculatorsHeat Pump Savings Calculator
A heat pump moves heat instead of creating it directly. Enter your own annual heat demand, f…
Heat Pump Amps and Wattage Calculator
Heat pump capacity is heat moved, not electricity consumed. Enter the rated BTU per hour and…
Home Insulation Savings Calculator
Model an insulation and air-sealing project from the heating and cooling portion of your bil…
Water Heating Cost Calculator
Estimate the useful heat needed to warm water, then adjust for heater efficiency and your en…
Space Heater Running Cost Calculator
Estimate a resistance space heater’s energy and running cost from its rated or measured watt…
Smart Thermostat Savings & Payback Calculator
ENERGY STAR says a certified smart thermostat saves the average household about 8% of heatin…
Gas vs Electric Heating Calculator
Compare gas and electric-resistance heating on the same annual useful-heat demand. The resul…
Tankless Water Heater Savings Calculator
Compare annual water-heating energy cost with a tankless scenario and the incremental instal…
Electric Radiator Running Cost Calculator
Estimate electricity use from the heater’s input watts and equivalent full-power runtime. A …
Electric Vehicles
3 calculatorsEV Charging Cost Calculator
Estimate home EV charging cost from daily distance, real-world efficiency, charging losses a…
EV vs Gas Savings Calculator
Compare energy cost only: wall electricity for an EV versus gasoline or petrol for a combust…
EV Charging Time Calculator
Estimate how long an EV will take to charge from its battery size, starting percentage, targ…
Appliances
13 calculatorsAppliance Running Cost Calculator
Convert representative operating watts and equivalent run time into energy and cost. For cyc…
LED Bulb Savings Calculator
Compare wattage only after matching brightness in lumens and checking fixture compatibility.…
Pool Pump Running Cost Calculator
Enter measured input watts or a reliable operating value—not motor horsepower alone—to estim…
Hot Tub Running Cost Calculator
Model heater electricity plus any separately known circulation, controls or jet energy. Actu…
Refrigerator Running Cost Calculator
A refrigerator cycles on and off all day. Enter the annual kWh from its EnergyGuide label—or…
Tumble Dryer Running Cost Calculator
Enter electricity per drying load rather than multiplying nameplate power by the full cycle …
Dishwasher Running Cost Calculator
Most of a dishwasher’s energy goes into heating water. Enter the energy per cycle and how of…
Washing Machine Running Cost Calculator
Enter the electricity used by the selected wash program and how often you run it. The result…
Electric Oven Running Cost Calculator
Electric ovens cycle their elements to preheat and maintain temperature. Enter input power a…
TV Running Cost Calculator
Enter your television’s on-mode wattage and daily viewing time to estimate its electricity u…
Freezer Running Cost Calculator
Use the exact freezer’s annual label or representative measured kWh. The calculator converts…
Electric Shower Running Cost Calculator
Convert the unit’s rated electrical input and household shower time into energy and electric…
Dehumidifier Running Cost Calculator
A dehumidifier cycles according to moisture load and humidistat settings. Enter representati…
Bills
3 calculatorsElectricity Bill Calculator & High-Bill Checker
Your bill is more than energy used — it also includes fixed charges, tax and levies. Estimat…
Electricity Carbon Footprint Calculator
Estimate electricity-related carbon dioxide from your billed kWh and a grid-average emission…
Time-of-Use Savings Calculator
Compare the energy charge for the same shiftable kWh at peak and off-peak rates. Use the exa…
Cooling
3 calculatorsAir Conditioner Running Cost Calculator
Air conditioning can dominate summer bills. Enter your AC’s cooling capacity, efficiency, ru…
How Much Does a Fan Cost to Run?
A typical 50 W fan running for 8 hours at $0.17/kWh costs about $0.07 per day or $2.04 acros…
Fan vs Air Conditioner Cost Calculator
A fan is normally much cheaper to run than air conditioning, but it moves air instead of low…
Battery
1 calculatorConversions
15 calculatorskW to kWh Calculator
Kilowatts measure power—the rate of energy use. Kilowatt-hours measure energy accumulated ov…
Watts to Amps Calculator
Need to know the current a device draws? This calculator converts watts to amps using your v…
Amps to Watts Calculator
Amps alone do not determine watts. Enter current, voltage, electrical system and power facto…
Watts to kWh Calculator
Watts measure power; kilowatt-hours measure energy used over time. Enter a wattage and how l…
kWh to Watts Calculator
Enter energy used in kilowatt-hours and the time period to calculate the average power in wa…
Amps to Kilowatts Calculator
This calculator converts a current in amps into power in kilowatts, using your voltage and p…
Kilowatts to Amps Calculator
Convert real power in kilowatts to current using the electrical system, voltage and power fa…
BTU to Watts Calculator
Heating and cooling gear is often rated in BTU per hour, while electrical power is in watts.…
kWh to Amps Calculator
Given how much energy was used (kWh) and over what time, this calculator finds the average c…
kWh to Amp-Hours Calculator
Convert energy in kilowatt-hours to battery capacity in amp-hours. Enter the kWh and nominal…
Watts to BTU/hr Calculator
Convert watts or wattage into the equivalent heat rate in BTU per hour. This is most direct …
Horsepower to Watts Calculator
Convert mechanical horsepower (550 foot-pounds force per second) to watts and kilowatts. Thi…
Wh to kWh Calculator
Watt-hours and kilowatt-hours are both units of energy. Enter any Wh value to convert it dir…
kWh to Wh Calculator
Kilowatt-hours and watt-hours are both units of energy. Enter any value in kWh to convert it…
mAh to Wh Calculator & Flight Check
Convert a battery or power bank from mAh to Wh, then compare the result with the FAA passeng…
Backup Power
2 calculatorsA useful estimate should show its workings.
Energy choices involve real money. Every HowMuchWatts tool uses an understandable formula, lets you replace the defaults, and explains where simplified estimates may differ from reality.