WattFigure API

Household electricity costs, state electricity prices and EV charging costs, as JSON. Built 2026-08-30 · rates for June 2026 · 50 appliances · 70 vehicles · 51 jurisdictions.

Endpoints

Path	Returns
`GET /v1/health`	Version, dataset period, counts
`GET /v1/rates`	All state rates, cheapest first
`GET /v1/rates/:state`	One state, e.g. `/v1/rates/california`
`GET /v1/appliances`	Appliance catalog; `?category=kitchen`
`GET /v1/appliances/:slug`	One appliance with its annual kWh
`GET /v1/vehicles`	EV catalog; `?make=tesla`
`GET /v1/vehicles/:slug`	One vehicle
`GET /v1/cost`	Running cost. `?state=&appliance=` or `?state=&watts=&hours_per_day=&days_per_year=`
`GET /v1/charge`	Charging cost. `?state=&vehicle=` or `?state=&kwh_per_100mi=&miles_per_year=`
`GET /v1/bulk/:dataset`	Whole dataset — key required
`GET /openapi.json`	OpenAPI 3.1 description

Try it

curl "https://api.wattfigure.com/v1/cost?state=california&appliance=space-heater"
curl "https://api.wattfigure.com/v1/charge?state=texas&vehicle=acura-zdx-awd"
curl "https://api.wattfigure.com/v1/rates/hawaii"

Tiers

Tier	What you get
Free	No key, no signup. List endpoints return up to 25 rows; computed endpoints are unrestricted. Fair-use rate limiting applies.
Pro	Send `X-API-Key`. Unpaginated lists, bulk dataset dumps, and no fair-use cap.

Data and licensing

Electricity prices: U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A (Form EIA-861M). Public domain. Vehicle consumption: U.S. EPA / DOE fueleconomy.gov, also public domain. Both are U.S. government works and carry no licence restrictions. The appliance usage catalog, the derived figures and this API are the operator's own work; attribution is appreciated.

Figures are estimates from published averages and stated assumptions. They are not a bill, a quote, or professional advice.