Charging a 2027 Rivian R1S Premium Long Range (22in) at home in Montana
A 2027 Rivian R1S Premium Long Range (22in) draws 39.9 kWh per 100 miles per the EPA; at Montana's 13.77¢/kWh residential rate that's $5.5 per 100 miles charged at home, versus $16.02 for a 25.5-mpg gas car covering the same distance. That works out to 65.7% cheaper per mile than gasoline in Montana — charging at home costs a fraction of what gas would here.
2027 Rivian R1S Premium Long Range (22in): yearly cost in Montana
Montana owners putting 15,000 annual miles on a 2027 Rivian R1S Premium Long Range (22in) spend about $825 on home electricity, compared to about $2,403 a gas-car equivalent would spend on fuel. Call it about $1,578 saved annually, at this mileage.
Filling up the 2027 Rivian R1S Premium Long Range (22in), in dollars
At Montana's rate, fully covering this 2027 Rivian R1S Premium Long Range (22in)'s 410-mile EPA range costs about $22.55 (163.7 kWh) — the energy the EPA test actually used, not the battery's rated size.
How this compares nationally
Among all 20,400 state-and-model combinations this site tracks, charging a 2027 Rivian R1S Premium Long Range (22in) in Montana ranks 6,954 for cost savings versus gas — 1 being the best deal nationally. Separately, the Rivian R1S Premium Long Range (22in) ranks 264 of 400 EV models for raw efficiency, and Montana ranks 10 of 51 for cheapest residential electricity.
Getting set up to charge a 2027 Rivian R1S Premium Long Range (22in) at home
Everything above is the per-mile and per-year cost once a home charger exists — getting one installed is a separate electrical job whose price depends on your panel and wiring, not the state average used here.
Ask a licensed Montana electrician to quote the install before this math becomes a real decision.
More on how this number was built
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.