Your gas station went invisible. Watt shows what a mile really costs.
Log each charge in seconds and Watt totals what you actually spend, measures your real efficiency from the odometer, and proves — in dollars — what your EV saves vs gas. Home, work, DC fast: see which kWh are eating your savings.
🔒 Local-first: your log never leaves your phone. We can't see it. Nobody can.
Every EV driver gets asked "so… is it actually cheaper?"
Now you answer with a number. Watt works with any EV, any charger, any year — no brand app, no OBD dongle, no login. You log what the charger screen says; Watt does the math the dealer never showed you.
Real cost per mile
Not the EPA sticker — yours. Log the odometer on two charges and Watt measures your true mi/kWh and what each mile costs you.
Savings vs gas, in dollars
Set the gas car you'd otherwise drive and every charge shows what those miles would have cost at the pump — and what you kept.
Home vs DC fast, exposed
Fast charging can cost 3× your home rate. Watt shows the average $/kWh of every source, so you see exactly where the savings leak.
Log by % or kWh
Type the kWh from the charger screen, or just "40% → 80%" — Watt converts using your pack size. Two taps for a home charge.
A whole garage
Two EVs? A Leaf and a Lightning? Each vehicle keeps its own rates, efficiency and gas comparison (Pro).
Cost report (Pro)
A clean PDF of what your EV really costs — per vehicle, per source, per month, with total savings. Perfect for expensing miles or tax season. CSV included.
Your car already tracks you. Watt doesn't.
- No car connection. Watt never talks to your EV, the charger network, or your utility — you type it, that's it.
- No account, no login, no email. Nothing to sign up for, nothing to leak.
- No location. "Home" and "DC fast" are labels you pick, not GPS pins.
- Everything on your device. Your log lives in your phone's storage. Delete the app and it's gone.
One tank of gas. Once.
Free covers your first 25 charges — enough to see your real numbers. Pro is a single one-time purchase that costs less than the fill-up you're not buying.
Free
- 1 vehicle, 25 charges
- Cost per mile & savings vs gas
- Measured efficiency
- Source & monthly insights
Pro
- Unlimited charges
- Unlimited vehicles
- PDF cost report
- CSV export