Electricity Price Index™ Methodology

National average baseline

The baseline is the U.S. average residential electricity rate (¢/kWh) published by the EIA for the latest complete reporting month — its U.S.-total figure, weighted by the electricity actually sold. This baseline is assigned an index value of 100.

The baseline is deliberately not the unweighted mean of the 51 jurisdiction rates. That mean gives a small, expensive jurisdiction the same weight as California and runs about 5% higher than the published U.S. figure, so using it would have overstated how far below average most states sit.

Formula

For each state:

indexValue = round((stateRate / nationalAverage) × 100)

Where stateRate is the state's average residential electricity price in ¢/kWh, and nationalAverage is the EIA's U.S.-total residential price for the same reporting month.

Interpretation

• Index > 100 — Above national average (higher electricity prices)
• Index = 100 — At national average
• Index < 100 — Below national average (lower electricity prices)

Limitations

The EPI uses state-level averages only. It does not account for within-state variation, time-of-use rates, or customer class differences. Rates use the EIA all-in average residential retail rate, which already includes delivery, fixed fees, and other utility charges; locally billed taxes vary by area.

Data sources

State rates come from our normalized state dataset. See sources for provenance.