Home Energy Calculators
Use these home energy calculators to estimate standby power, appliance electricity cost, device runtime, and practical household power decisions. The goal is not to guess from labels alone, but to turn watts, hours, kWh, and local electricity rates into useful numbers.
Home energy calculators
Standby Power Cost Calculator
Estimate standby power, vampire load cost, avoidable savings, and smart plug payback for idle home devices.
Home energy answer library
Home energy questions usually need three inputs: watts, hours, and price per kWh. The hard part is deciding whether a device is an active load, a standby load, or an essential always-on load.
Standby power and vampire loads
Start here when the question is whether idle electronics are quietly adding cost to the electric bill.
- Standby Power Cost CalculatorAdd idle devices, watts, hours, electricity price, and avoidable loads to estimate yearly standby cost and payback.
- TV Electricity Cost CalculatorEstimate active TV cost and standby cost from watts, daily viewing hours, and electricity price.
- Router Backup Power Runtime CalculatorEstimate how long backup power can keep routers, modems, ONTs, and mesh nodes online.
- Calculation methodologySee how DeviceCalc documents formulas, assumptions, limits, and practical estimates.
Appliance electricity cost
Use these tools when a device runs for long hours, cycles on and off, or has a meaningful yearly kWh label.
- Refrigerator Energy Cost CalculatorEstimate refrigerator energy cost from kWh/year, watts, compressor run time, and electricity price.
- Freezer Energy Cost CalculatorEstimate chest freezer or upright freezer electricity cost from kWh/year, watts, placement, and local rates.
- AC Electricity Cost CalculatorEstimate air conditioner electricity use and cost from power, hours, and electricity price.
- AC Running Cost CalculatorEstimate hourly, nightly, weekly, monthly, and seasonal air conditioner running cost.
- Air Purifier Electricity Cost CalculatorEstimate air purifier electricity use from watts, daily runtime, electricity price, and number of units.
- Dehumidifier Electricity Cost CalculatorEstimate dehumidifier electricity cost from watts, annual kWh, runtime, efficiency, and local rates.
Choose a home energy calculator by question
A standby power estimate is useful when electronics stay ready while idle. Appliance energy calculators are better when the device actively runs, cycles, heats, cools, dries, or filters air.
Available now
The Standby Power Cost Calculator estimates vampire power from idle devices and shows whether a smart plug or switched power strip can realistically pay back. It works best when you can enter measured standby watts from a plug-in meter or a credible device specification.
Related electricity tools
Use these related calculators when the device has a normal operating load rather than a small idle load.
TV Electricity Cost Calculator
Estimate TV electricity use and running cost from watts, hours, electricity price, and standby power.
Refrigerator Energy Cost Calculator
Estimate refrigerator electricity use and annual running cost from kWh, watts, and electricity price.
Freezer Energy Cost Calculator
Estimate chest freezer or upright freezer electricity cost from kWh/year, watts, placement, and electricity price.
AC Electricity Cost Calculator
Estimate air conditioner electricity use and cost from power, hours, and electricity price.
AC Running Cost Calculator
Estimate hourly, nightly, weekly, monthly, and seasonal air conditioner running cost.
Air Purifier Electricity Cost Calculator
Estimate air purifier electricity cost from watts, daily runtime, annual kWh, electricity price, and number of units.