Free home energy savings calculators
Accurate, no-nonsense calculators for solar payback, heat pumps, EV charging, appliance running costs and more. No signup, no fluff — just answers.
Solar
Solar Panel Payback Calculator
Solar pays off only after it has saved you more than it cost to install. This calculator estimates y…
SolarHome Battery Payback Calculator
A home battery saves money by storing cheap (or solar) electricity and using it when power is expens…
SolarSolar System Size Calculator
Before pricing solar, you need to know what size system covers your usage. This calculator estimates…
SolarSolar Savings Calculator
Wondering how much solar would shave off your bill? This calculator estimates your savings from the …
SolarSolar Panel Cost Calculator
Solar is usually priced per watt of capacity. Enter your system size and price per watt to estimate …
SolarSolar Export Earnings Calculator
When your panels make more than you use, the surplus is exported to the grid for a payment. This cal…
Heating
Heat Pump Savings Calculator
Heat pumps move heat instead of burning fuel, so they can deliver 3–4 units of heat per unit of elec…
HeatingHome Insulation Savings Calculator
Insulation cuts the energy you lose through walls, roof and floors — lowering both heating and cooli…
HeatingWater Heating Cost Calculator
Heating water is one of the biggest energy uses in most homes. This calculator estimates the daily a…
HeatingSpace Heater Running Cost Calculator
Electric space heaters are cheap to buy but can be expensive to run. This calculator shows the cost …
HeatingThermostat Savings Calculator
Lowering your heating thermostat even slightly can noticeably cut your bill. This calculator estimat…
HeatingGas vs Electric Heating Calculator
Which is cheaper to heat your home — gas or electric? This calculator compares the annual cost of bo…
HeatingTankless Water Heater Savings Calculator
Tankless water heaters avoid the standby losses of keeping a full tank hot. This calculator estimate…
HeatingElectric Radiator Running Cost Calculator
Electric radiators turn power straight into heat, so wattage directly drives cost. Enter yours to se…
Electric Vehicles
EV Charging Cost Calculator
Charging an EV at home is usually far cheaper than petrol, but the exact cost depends on your effici…
Electric VehiclesEV vs Gas Savings Calculator
Electric cars usually cost far less per mile than petrol — but how much would you actually save? Thi…
Electric VehiclesEV Charging Time Calculator
Charging time depends on your battery size, how much you need to add, and how fast your charger deli…
Appliances
Appliance Running Cost Calculator
Any appliance — a fridge, heater, gaming PC or AC unit — costs money every hour it runs. Enter its w…
AppliancesLED Bulb Savings Calculator
LED bulbs use a fraction of the power of old incandescent or halogen bulbs. This calculator shows yo…
AppliancesPool Pump Running Cost Calculator
A pool pump often runs for hours every day, making it one of the largest energy users in a home with…
AppliancesHot Tub Running Cost Calculator
Hot tubs are notorious energy users, mostly from the heater keeping water warm. This calculator esti…
AppliancesRefrigerator Running Cost Calculator
A fridge runs 24/7, so even a small power draw adds up. Enter its yearly energy rating to see what i…
AppliancesTumble Dryer Running Cost Calculator
Tumble dryers are among the most power-hungry household appliances. See what yours costs per load an…
AppliancesDishwasher Running Cost Calculator
Most of a dishwasher’s energy goes into heating water. Enter the energy per cycle and how often you …
AppliancesWashing Machine Running Cost Calculator
A washing machine’s cost is driven mostly by how hot you wash. Enter the energy per load and your us…
AppliancesElectric Oven Running Cost Calculator
Ovens draw a lot of power but cycle on and off to hold temperature. Enter the power and weekly use t…
AppliancesTV Running Cost Calculator
Modern TVs are fairly efficient, but big screens watched for hours still add up. Enter your TV’s wat…
AppliancesFreezer Running Cost Calculator
A freezer runs constantly, so its yearly energy rating tells you almost everything. Enter it to see …
AppliancesElectric Shower Running Cost Calculator
Electric showers are high-power appliances — often 8–10 kW. Enter the rating and your shower habits …
AppliancesDehumidifier Running Cost Calculator
Dehumidifiers are modest in power but often run for hours. Enter the wattage and usage to see the ru…
Bills
Electricity Bill Calculator
Your bill is more than just energy used — it includes fixed daily charges and tax. This calculator e…
BillsElectricity Carbon Footprint Calculator
Every kWh of electricity carries a carbon cost that depends on how your grid generates power. This c…
BillsTime-of-Use Savings Calculator
On a time-of-use tariff, running appliances at off-peak times costs far less. This calculator estima…
Cooling
Air Conditioner Running Cost Calculator
Air conditioning can dominate summer bills. Enter your AC’s cooling capacity and efficiency to see w…
CoolingFan Running Cost Calculator
Fans use a tiny fraction of the power of air conditioning. Enter the wattage and run time to see jus…
Battery
Conversions
kW to kWh Calculator
Power (kW) is the rate of use; energy (kWh) is power used over time. This calculator converts a kW r…
ConversionsWatts to Amps Calculator
Need to know the current a device draws? This calculator converts watts to amps using your voltage a…
ConversionsAmps to Watts Calculator
This calculator converts a current in amps into power in watts, using your voltage and power factor.…
ConversionsWatts to kWh Calculator
Watts measure power; kilowatt-hours measure energy used over time. Enter a wattage and how long it r…
ConversionskWh to Watts Calculator
If you know how much energy something used (kWh) and over how long, this calculator works out the av…
ConversionsAmps to Kilowatts Calculator
This calculator converts a current in amps into power in kilowatts, using your voltage and power fac…
ConversionsKilowatts to Amps Calculator
This calculator converts power in kilowatts into the current it draws in amps, using your voltage an…
ConversionsBTU to Watts Calculator
Heating and cooling gear is often rated in BTU per hour, while electrical power is in watts. This ca…
ConversionskWh to Amps Calculator
Given how much energy was used (kWh) and over what time, this calculator finds the average current d…
ConversionsWatts to BTU Calculator
Convert electrical power in watts into a heat rate in BTU per hour — handy for comparing heaters and…
ConversionsHorsepower to Watts Calculator
Convert mechanical horsepower into watts and kilowatts — useful for sizing motors, pumps and generat…
ConversionsWh to kWh Calculator
Watt-hours and kilowatt-hours measure the same thing at different scales. Convert between them and s…
ConversionsmAh to Wh Calculator
Battery capacity is often given in mAh, but airlines and power stations use Wh. Convert between them…
Backup Power
Why these calculators?
Energy decisions involve real money, but most online calculators are either oversimplified or buried in ads and signup walls. Every tool here uses a transparent formula (explained on each page), updates as you type, and works on any device. They give clear ballpark estimates to help you decide what to look into further — not financial advice.