Size Power & Cooling,
Prevent Circuit Breaker Trips.
Free home energy calculators: air conditioner BTU sizing, appliance electricity cost, generator wattage checklists, and how many solar panels offset your bill.
Room BTU Heat Loads
20 BTU per square foot base adjusted for ceiling height, sunny windows, and kitchen cooking appliances.
Inductive Motor Surge Watts
Refrigerator compressors and well pumps draw 2x–3x running wattage during initial rotor startup.
Generator Fuel Runtime
Calculate gallon consumption per hour across 50% vs 100% electrical continuous loads.
WattGuide Calculators
AC BTU Calculator
Air conditioner sizing for any room — square footage plus ceiling, sun, occupants, and kitchen adjustments.
Appliance Electricity Cost Calculator
What any appliance costs per day, month, and year — from nameplate watts and your actual utility rate.
Generator Size Calculator
What to keep running in an outage — running watts plus starting surge, sized with an electrician's logic.
Solar Panel Calculator
How many panels to offset your bill — from your actual kWh usage, local sun-hours, and panel wattage.
Technical Reference Guides
What Size AC Do I Need? BTU Sizing Without the Guesswork
The 20-BTU-per-square-foot baseline, the adjustments that actually matter, and why oversized air conditioners feel clammy.
What Your Appliances Actually Cost: The Electricity Math
Watts, duty cycles, and the effective rate — how to compute any appliance's real yearly cost and find the bill's actual villains.
Home Generator Sizing: What Actually Matters
Running watts, starting surges, and the checklist method — how to buy the right generator instead of the biggest one.