Estimate appliance kWh and cost by day, week, average month, current calendar month, and year, with an optional regional CO₂ factor.
Choose your path
Estimate constant-rate appliance energy cost with distinct annual-average and current-calendar months, plus optional rather than invented electricity emissions.
Estimate an appliance’s bill contribution from realistic power and runtime.
Enter watts, hours/day, and marginal $/kWh; inspect daily through annual results.
Can reproduce kWh and cost and knows tiered/time-of-use/fixed charges are outside the model.
Avoid a hidden 30-day month assumption.
Compare annual÷12 average month with the current calendar month.
For 300W×8h at $0.15, sees $10.95 average month and $11.16 for August’s 31 days.
Estimate operating CO₂ only from a relevant factor.
Leave the factor blank for cost-only or enter a utility/regional lb/kWh value.
No universal factor is invented, and appliance comparisons are labeled as same-hours scenarios rather than typical usage.
This tool is part of these guided projects. Each project provides step-by-step instructions with checklists and all the tools you need in one place.
Turn exact bills, tariffs, measured or documented equipment use and household constraints into bounded cost scenarios, authorized changes and weather-aware verification.
Build a source-led home-solar decision dossier from bills, site evidence, production scenarios, written proposals, current incentives, contracts, commissioning, and measured results.
Tools you might need next
Calculate an entered utility bill reduction and simple payback, or compare observed bill averages without assuming what caused the change.
Compare documented annual electricity use for two appliances using one local rate, entered upgrade cost, and explicit planning horizon.
Allocate exactly 100% of monthly income, compare non-negative actual spending, expose fixed-dollar extras, and review transparent balances and planning ratios.
Power is converted from watts to kilowatts, multiplied by daily runtime, then multiplied by the entered energy rate.
Daily cost = watts × hours/day ÷ 1,000 × rate/kWhAnnual cost uses 365 days. Average month divides annual cost by 12; the calendar view uses the actual number of days in the current month.
Annual CO₂ is shown only when a non-negative lb/kWh factor is entered. The constant-rate model excludes taxes, tiers, time-of-use schedules, and demand charges.
Updated: July 2026
A homeowner combines measured wattage, realistic daily hours, and the marginal bill rate to estimate one appliance's annual contribution.
A student compares several nominal wattages at the same daily runtime while keeping clear that this is not typical usage.
A user enters a utility or regional emissions factor to estimate annual operating CO₂ without treating a national average as universal.
Model an appliance from watts, daily runtime, and your electricity rate. Compare annual÷12 average-month cost with the actual length of the displayed month, and add an emissions factor only when you have a relevant utility or regional value.