Run the numbers before you buy.
No sign-up, no email wall — just three calculators that answer the questions our reviews keep raising. Each one shows the formula it uses and cites the federal data behind it, so you can trust the figure and check the math.
Smart Thermostat Savings Calculator
Turn the Department of Energy’s setback rule into a real dollar figure — and see how fast the thermostat pays for itself.
LED Savings Calculator
Compare old bulbs to LEDs across a whole batch and a full decade — energy plus the replacement bulbs you stop buying.
Phantom Load Calculator
Add up the “vampire” standby power your gear draws around the clock and price it for the year, device by device.
Sourced
Every constant comes from the DOE, ENERGY STAR, the EIA, or LBNL — and we link the source on each page.
Transparent
Each tool prints the exact formula with your numbers filled in, so nothing is hidden in a black box.
Tested
The math is checked against the agencies’ own worked examples — plug in their inputs, get their answer.