Montana home charging cost for the 2027 Rivian R1S Premium (22in)

A 2027 Rivian R1S Premium (22in) draws 39.5 kWh per 100 miles per the EPA; at Montana's 13.77¢/kWh residential rate that's $5.44 per 100 miles charged at home, versus $16.02 for a 25.5-mpg gas car covering the same distance. Charging at home costs a fraction of what gas would here: 66.1% less than gas per mile, here specifically.

Annual cost, at 15 thousands miles a year

At fueleconomy.gov's default of 15,000 annual miles, the 2027 Rivian R1S Premium (22in) costs roughly $815 a year to charge at home in Montana, against roughly $2,403 a year for an equivalent gas car. That's a savings of about $1,588 a year.

Filling up the 2027 Rivian R1S Premium (22in), in dollars

Covering the 2027 Rivian R1S Premium (22in)'s EPA-rated 329-mile range takes about 129.9 kWh, which costs about $17.88 at Montana's residential rate — figured from the EPA's own combined range and consumption numbers, not the pack's nameplate capacity.

How this compares nationally

This combination ranks 6,630 of 20,400 state/model pairs for cost savings against gas (1 is cheapest). The Rivian R1S Premium (22in) alone ranks 249 of 400 models for efficiency; Montana alone ranks 10 of 51 states for electricity price.

Next step: home charger installation

The numbers above assume Level 2 home charging is already in place — the electrical work behind that is a real, separate cost that varies by panel, wiring, and local labor rates, not something this page's per-mile math includes.

Ask a licensed Montana electrician to quote the install before this math becomes a real decision.

Where these figures come from

The methodology guide names the exact EIA and EPA tables behind this page's numbers. At 13.77¢/kWh, Montana sits in the middle of the national range — the guide to why charging cost varies by state shows where.