Electricity cost

Usage-day energy = appliance watts/1000 × hours. For two tariffs use the same average mains-side power and separate non-overlapping times, totaling at most 24 hours. Disabled second tariff is ignored. Cost = kW × (hours1×price1 + hours2×price2). Prices are per kWh in the chosen currency; no fixed fees, extra taxes beyond the entered price, demand charges or parking fees.

Year = usage day × entered days, from 0 to 366. Monthly average = year/12, not an actual calendar month or a fixed 30-day month. Usage day means a day with this usage profile. Zero days keeps per-use-day values but makes year/month zero. Zero power, time and price are valid. Use actual average power during the entered times, not unchecked maximum nameplate power. Changing operating states and standby outside those times are not added automatically.

Optional CO₂: no assumed grid mix. Annual energy × entered kg CO₂/kWh factor. Blank hides it; zero explicitly uses a zero factor. Match region, data year and system boundary; no automatic CO₂e, life-cycle or avoided-emissions estimate. EPA eGRID lists regional CO₂/CO₂e rates in lb/MWh; do not enter these directly as kg/kWh. No rates from that table are loaded as defaults.

Calculate/Enter; edits clear output; Reset restores examples. Active fields are checked; invalid CO₂ opens its section. No storage. Virginia Tech energy use explains W×time/1000 and usage days. Power, prices and times are examples, not current tariff recommendations.