15 FOCUSED TOOLS
Electricity use & bills calculators
Translate power, time and entered tariffs into energy charges.
Choose the right calculation
Watts describe power and kilowatt-hours describe energy. Fixed charges do not vary directly with consumption. Devices with thermostats or cycling loads need measured average energy or realistic operating time.
Find a tool for your question
Appliance Energy Calculator
Estimate electricity consumption from appliance power and operating hours.
Electricity Cost Calculator
Calculate energy charges from consumption and a manually entered unit rate.
LED Savings Calculator
Estimate energy savings from replacing equal-use lighting with lower-wattage bulbs.
Energy Payback Calculator
Estimate simple payback time for an efficiency upgrade.
Heating Energy Calculator
Estimate ideal energy required to raise water temperature.
Electricity Bill Calculator
Combine metered energy charges and a fixed daily charge.
Appliance Annual Cost Calculator
Estimate annual electricity spending for a constant-power appliance.
Standby Power Cost Calculator
Estimate annual electricity cost for a load left continuously in standby.
Area Normalised Insulation R Value Calculator
Find thermal resistance per unit area from insulation thickness and conductivity.
U Value From R Value Calculator
Convert an entered total thermal resistance into a heat-transmittance coefficient.
Heat Loss From U Value Calculator
Estimate steady heat transfer through an envelope area using an overall U-value.
Heating Fuel Input Calculator
Estimate input fuel energy for a useful-heating demand.
Heat Pump Electricity Calculator
Estimate heat-pump electricity from delivered heat and an assumed COP.
Water Heating Cost Calculator
Estimate energy spending for a water-temperature increase under a stated efficiency.
Building Energy Intensity Calculator
Normalise entered building energy use by floor area.
Can I multiply rated watts by 24 hours for every appliance?
Only if it actually draws that power continuously. Cycling and variable-power appliances require a better average-use estimate.
Useful next steps in other categories
Battery Runtime Calculator
Estimate runtime from nominal battery energy, usable fraction and load power.
EV Charging Cost Calculator
Estimate the electricity cost for adding energy to a vehicle battery.
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