Calculators for everyday home questions
Some questions need a number, not a rule of thumb. Each calculator shows its method and sources, works in U.S. and metric units, and runs entirely in your browser.
$0.27 per hour for a 1,500 W space heater at 18.3¢/kWh
Appliance Energy Cost Calculator
What any appliance costs to run per hour, month and year.
Electricity & Energy 12,000 BTU for a 500 sq ft room with normal sun
Room AC Size Calculator
The BTU rating a room needs, using the ENERGY STAR method.
Heating & Cooling 37% max indoor humidity for double-pane glass at 20°F outside
Window Condensation Calculator
Will your windows sweat tonight? Find the humidity limit for your glass.
Air & Moisture Repair a $250 fix on a 4-year-old $900 dishwasher
Repair or Replace Calculator
Is a repair worth it? Compare cost, age and expected lifespan.
Kitchen Appliances