How much does a hot tub cost to run in a cold winter?

Start with usage, because that part travels. National figures put a typical spa at 100 to 300 kWh a month, with winter running 30 to 50% higher. For a winter around −20 °F that gives about 200 to 350 kWh a month for a well-insulated tub and 400 to 700 or more for a poor one. Owner reports in a single rural forum thread span roughly $25 a month to $300 added to a winter bill, which shows how far insulation moves the number.

Then apply your rate. EIA residential averages for 2026 to date run from 12.4¢/kWh in North Dakota through 18.2¢ nationally to 30¢ in Maine. At those three rates a well-insulated tub costs about $25–$43, $36–$64 and $60–$105 a month; a poorly insulated one $49–$87, $73–$127 and $120–$210. Use the all-in rate from your bill, including delivery charges.

Two levers matter more than the rate: the cover, since a waterlogged one is the hidden drain owners describe, and the setpoint. Dropping it a degree or two saves up to about 10%.