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
Any appliance — a fridge, heater, gaming PC or AC unit — costs money every hour it runs. Enter its wattage and h…
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
Solar pays off only after it has saved you more than it cost to install. This calculator est…
Home Battery Payback Calculator
A home battery saves money by storing cheap (or solar) electricity and using it when power i…
Solar System Size Calculator
Before pricing solar, you need to know what size system covers your usage. This calculator e…
Solar Savings Calculator
Estimate the value of solar electricity you use at home plus the credit or payment for surpl…
Solar Panel Cost Calculator
Solar is usually priced per watt of capacity. Enter your system size and price per watt to e…
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
Insulation cuts the energy you lose through walls, roof and floors — lowering both heating a…
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
Electric space heaters are cheap to buy but can be expensive to run. This calculator shows t…
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
Tankless water heaters avoid the standby losses of keeping a full tank hot. This calculator …
Electric Radiator Running Cost Calculator
Electric radiators turn power straight into heat, so wattage directly drives cost. Enter you…
Electric Vehicles
3 calculatorsEV Charging Cost Calculator
Charging an EV at home is usually far cheaper than petrol, but the exact cost depends on you…
EV vs Gas Savings Calculator
Electric cars usually cost far less per mile than petrol — but how much would you actually s…
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
Any appliance — a fridge, heater, gaming PC or AC unit — costs money every hour it runs. Ent…
LED Bulb Savings Calculator
LED bulbs use a fraction of the power of old incandescent or halogen bulbs. This calculator …
Pool Pump Running Cost Calculator
A pool pump often runs for hours every day, making it one of the largest energy users in a h…
Hot Tub Running Cost Calculator
Hot tubs are notorious energy users, mostly from the heater keeping water warm. This calcula…
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
Tumble dryers are among the most power-hungry household appliances. See what yours costs per…
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
A washing machine’s cost is driven mostly by how hot you wash. Enter the energy per load and…
Electric Oven Running Cost Calculator
Ovens draw a lot of power but cycle on and off to hold temperature. Enter the power and week…
TV Running Cost Calculator
Modern TVs are fairly efficient, but big screens watched for hours still add up. Enter your …
Freezer Running Cost Calculator
A freezer runs constantly, so its yearly energy rating tells you almost everything. Enter it…
Electric Shower Running Cost Calculator
Electric showers are high-power appliances — often 8–10 kW. Enter the rating and your shower…
Dehumidifier Running Cost Calculator
Dehumidifiers are modest in power but often run for hours. Enter the wattage and usage to se…
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
Every kWh of electricity carries a carbon cost that depends on how your grid generates power…
Time-of-Use Savings Calculator
On a time-of-use tariff, running appliances at off-peak times costs far less. This calculato…
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
Power (kW) is the rate of use; energy (kWh) is power used over time. This calculator convert…
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
This calculator converts a current in amps into power in watts, using your voltage and power…
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
This calculator converts power in kilowatts into the current it draws in amps, using your vo…
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 into watts and kilowatts — useful for sizing motors, pumps and…
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.