What each of the six is for
The electricity bill calculator estimates a whole monthly electric bill from your usage and your rate, with separate fields for fixed monthly charges and for tax, because those are the two things a rate-times-kilowatt-hours estimate always misses. Pick your state to load its average rate, then override it with the real number off your own bill.
The kWh cost calculator answers a narrower question: what does one kilowatt-hour cost me, and what does running a given number of watts for a given number of hours cost per hour, day, month and year. Use it when you want to price a single behaviour rather than a bill.
The appliance energy cost calculator prices any single appliance from its wattage and its runtime. It loads realistic duty-cycle hours for 32 common appliances — running time, not hours plugged in — and you can override both numbers with your own.
The water and sewer bill calculator handles the awkward parts of a water bill: usage measured in CCF or thousands of gallons, a separate sewer rate charged on water volume, the summer sewer cap many utilities apply, and fixed meter and stormwater charges.
The natural gas and propane calculator works in therms or CCF for piped gas and in gallons for propane, with the unit conversions built in, so you can compare a delivered propane price against a metered gas rate without doing it on paper.
The split bill calculator is the odd one out, and the most used. It divides an itemised bill between people by what each person actually ordered, apportioning tax and tip in proportion to each subtotal rather than evenly — so the person who ordered the expensive thing carries more of the tip. It also splits evenly if you would rather.
They run in your browser and transmit nothing
All six are plain JavaScript running on your own device. There is no account, no email gate, no sign-up wall and no server round trip: the numbers you type are never sent anywhere, because there is nowhere for them to be sent. You can close the tab and the inputs are gone.
That is a deliberate design decision, not a technical limitation. A calculator that asks for your postcode before it will show you a result is not gathering information it needs for the arithmetic — the arithmetic does not require it — it is qualifying a lead. Nothing here asks who you are, where you live or who your utility is, because none of that changes what watts times hours divided by a thousand comes to.
Every tool also shows its working rather than just a total, so you can check the result against your own bill and see which input is responsible when it disagrees. If you want to understand the bill you are checking against, reading your electric bill line by line is the place to start.
Why a site that takes no supplier money gives a different answer
Most consumer energy calculators are published by people who are paid when you switch something. A comparison site earns a commission on each enrolment; a supplier's calculator exists to produce a quote; an installer's savings estimator exists to produce a proposal. None of that is illegitimate, but it shapes the defaults. Assumptions get chosen at the optimistic end, the comparison baseline is the least flattering plan available, and the output is a number that argues for an action.
This site takes no money from energy suppliers, retailers or installers, and there is no enrolment button anywhere on it, so the arithmetic has nothing to sell. That is the whole of the claim. These are not sophisticated models — they are multiplication and addition done carefully, with defaults sourced from EIA and labelled with the period they come from. The value is in the sourcing and in being told plainly what is not included.
So here is what is not modelled. Tiered and inclining-block electricity rates, where the price rises after a baseline allowance, are not applied automatically; nor are time-of-use periods, seasonal rate changes, demand charges, minimum bills, or the riders and surcharges that vary by utility and month. You can capture most of them by entering your own all-in rate — your bill total divided by the kilowatt-hours on it — in place of an average, and by putting fixed fees in the fixed-charge field. Appliance figures are typical values with real spreads around them; your fifteen-year-old unit is not the median unit.
And a state average is a description of a population, not a forecast for your household. The state-by-state averages are there for comparison and sanity-checking, and they make good defaults, but the figures from your own bill will always give you a better answer than ours.