THE DETAILS
Clear numbers, clear limits.
BillMellow editorial · Updated October 25, 2026
BillMellow calculates appliance energy as watts ÷ 1,000 × hours. It multiplies energy by the rate you supply. Monthly results use the days entered; annual results assume the same daily use for 365 days.
The initial $0.18/kWh, wattages and usage values are illustrative, editable examples. They are not your utility’s rate or measured consumption.
The company directory uses EIA-861 reporting data for 2025. Detailed residential records come from the OpenEI Utility Rate Database. The website includes historical records and does not certify tariffs as current, complete or applicable to a particular address.
Tiered charges, demand charges, credits, tax treatment and separate supply/delivery contracts require additional modelling. Our basic calculators do not silently substitute a statewide average or apply an unverified company tariff.
We distinguish source effective dates, source revisions and our collection time. Automated local collection does not by itself update the deployed website.
Bill changes and replacement payback
Usage effect = change in kWh × average of both variable rates. Rate effect = change in variable rate × average of both kWh totals. Changes in fixed charges, taxes and credits complete the total difference. Usage includes billing-period length. Tiers and timing can change the average rate without a tariff increase.
Replacement savings = annual kWh difference × variable rate. Simple payback = purchase cost ÷ positive annual savings. Zero or negative savings have no energy-cost payback. Financing, maintenance, rebates and future rates are excluded.
Two-plan scenario comparison
Monthly modeled cost = kWh × combined variable rate + fixed monthly charges − eligible credit. A credit is eligible when the entered kWh reaches its threshold. Twelve-month comparisons repeat the same month. First-year net savings for A → B subtract the entered switching cost once. Recovery time divides switching cost by positive monthly savings.
The usage table shows different consumption levels and points around entered credit thresholds. A simple crossover is calculated only when threshold credits do not create jumps. This is a flat-rate scenario comparison; tier allocation, time-of-use profiles, taxes, demand charges, minimum bills and credit caps are excluded. Importing a public record does not certify it as current or available. Only recognized monthly fixed-fee units are automatically loaded; otherwise the fee is set to 0 and flagged for review.