Everything on this site is an estimate built on stated assumptions — offered as-is. What that means, concretely:

The estimate is a model, not a meter

The estimator multiplies watts × hours × days ÷ 1,000 and prices the result at your rate. That arithmetic is exact; the inputs feeding it are honest approximations:

• Wattages are typical midpoints. “Window AC 1,000 W” represents the middle of a 500–1,500 W range; your unit is a specific model with a specific draw. The range under each device name is the caveat, and the watts field is editable for exactly this reason.
• Duty-cycled figures smooth real behavior. The fridge’s ~100 W average hides a compressor cycling between ~0 and ~400 W; your water heater’s real hours depend on tank size, inlet temperature and how your household showers. Two identical homes can legitimately differ by 30%+.
• Hours are your guess. We can’t know whether the PC runs 3 or 9 hours a day, and that input swings the result more than any wattage refinement.

Where estimates diverge from real bills

Even with perfect inputs, your statement includes things this model deliberately doesn’t: fixed customer charges, tiered and time-of-use pricing, fuel adjustments, taxes, and loads not on the list (central HVAC is the big one). A good estimate typically lands within ~20–30% of a real bill when the major loads are listed; treating it as your exact bill is a misuse we can’t prevent but can warn against here.

Reference figures and rates

Device wattages, the ≈3%-per-degree thermostat heuristic, the ~450 kWh/yr ENERGY STAR fridge baseline, and the US average-usage comparisons come from public references (DOE, EIA, ENERGY STAR, FTC EnergyGuide, LBNL) as we understand them. Sources get revised and figures get stale — where our number and a newer authoritative source disagree, the source wins and we want the correction.

Not professional advice

Nothing here is financial, legal, electrical-contractor or energy-audit advice. Actual decisions — panel upgrades, HVAC replacement, solar sizing, disputing a bill — deserve a licensed professional or your utility’s own audited usage data, not a browser estimate. The guides explain conventions and math; they are not a substitute for a professional looking at your house.

Advertising

The site may show third-party ads (e.g. Google AdSense) to offset hosting. Advertisers have no influence on wattage figures, calculations or article content — the arithmetic doesn’t know an ad exists.

Liability

Use of this site is at your own risk. To the maximum extent permitted by law, PowerBill and its maintainers accept no liability for losses connected with its use — including budgeting decisions made on modeled figures, purchases made on estimated savings, and disputes with your utility. For any number that will cost you real money, verify it against your meter, your nameplate, or your bill.