About Whatt | Whatt

Whatt is a free tool that helps you see what power and water actually cost at home — by appliance, fixture, and habit.

It started from the kinds of questions that pop into your head at home and never get a straight answer. What does it actually cost to leave a fan on all day? Do a few extra flushes really show up on the water bill? And what about those warnings grandparents love — “stop flipping that light switch on and off, you’ll run up the bill” — as if the room were a strobe light? Those questions needed calm, simple numbers in one place. That is what Whatt grew into.

Whatt is an independent personal project at whatt.net. There is no company login and no account. Estimates run in your browser. Settings, rates, and My Home stay on the device you are using. Questions go to support@whatt.net.

What it is

A free estimator for home power and water. Use your own bill rate when you have it, or start from typical area averages. My Home and rates stay on this device. You can save a household list, download a backup file, and restore it later — nothing is stored in a Whatt cloud account because there is not one.

The catalog covers the loads that actually move a residential bill: cooling and heat, water heat, laundry, cooking (including a gas stove, where fuel is counted using your power rate as a stand-in), lights, well pumps, leaks, irrigation, and the quiet always-on boxes. Each card is one habit you can set, not a full utility statement.

How it works

Pick something you use, set how you use it, and Whatt shows a simple cost estimate. Optional “What if” ideas help you compare small changes — an extra hour, a leak left for a week, a second dryer cycle. Power math is watts, hours, and your ¢/kWh. Water math is gallons (or flow × minutes) and your water rate. Gas dryer, gas furnace, and gas stove put typical fuel use into that same total so the card is not quietly too cheap.

For hot water, the estimate needs to know how the water is heated. The default is an electric tank so the number is not accidentally low. A How-to-tell page describes gas tanks, propane, oil, heat pumps, tankless boxes, and house boilers in plain language.

What it is not

Whatt is not a utility bill, a quote from a provider, a load calculation for a panel, or National Electrical Code design. Real bills include customer charges, taxes, tiers, time-of-use windows, demand charges, and sewer minimums that this tool does not invent. If the estimate and the statement disagree, the statement wins — then use Find your rate so the next estimate is closer.

Privacy in one paragraph

Rates and My Home never leave this browser as an account. Optional Use my location may send browser-provided coordinates to BigDataCloud, then OpenStreetMap Nominatim, only to suggest a ZIP or state. You can type a ZIP instead. Ads, if Google serves them, use Google’s cookies under the Privacy Policy.

Disclaimer

Whatt provides educational estimates only. These figures are not financial advice. If a number feels off, change watts, hours, or rate, or write support@whatt.net.

Why a calculator still needs this page

The app is the estimator. This page is the project: who runs it, what the numbers mean, and what they are not. Google and readers both land here when they want more than a blank tool.