If you're shopping for the cheapest hot tub to run, the type of spa you choose matters far more than the brand. Operating costs vary widely across traditional built-in hot tubs, inflatable models, and portable spas like Softub. Here's a full cost comparison to help you see where the real savings are, and where a lower price tag can actually cost more over time.
Traditional Hot Tubs: Highest Ongoing Cost
Traditional acrylic or fiberglass hot tubs are built for durability and larger seating capacity, but that comes with a real energy tradeoff. Their larger shells lose heat faster, especially in colder climates, so the heater runs more often to maintain temperature. Monthly electricity costs commonly run $30 to $65 higher than a more efficient portable spa, and that number climbs further in winter months when heat loss accelerates.
Inflatable Hot Tubs: Cheap Upfront, Expensive to Maintain
Inflatable spas often look like the cheapest option at first glance, with some models priced under $1,000. But inflatable walls provide minimal insulation, so they lose heat quickly and require frequent reheating, particularly outdoors or in cooler weather. Owners frequently report needing to run the heater almost constantly to hold temperature, which can erase the upfront savings within a single season. Durability is also a common complaint, since punctures and liner wear often mean replacing the unit entirely after a few years.
Softub: Lowest Verified Operating Cost
Independent testing from the California Energy Commission found that a Softub can be maintained at 102 degrees for around $9.60 a month in an average climate, using roughly 4 kilowatt hours of electricity per day. That efficiency comes from Softub's Heat Recovery Technology, which combines the pump motor and heater into a single HydroMate unit rather than running them separately. Unlike an inflatable spa, a Softub's marine-grade vinyl and foam construction actually holds heat well, so the low running cost doesn't come at the expense of performance. See the full technology breakdown for more on how this works.
The Full Cost Picture, Not Just the Sticker Price
The cheapest hot tub to buy isn't always the cheapest hot tub to own. An inflatable spa might cost a few hundred dollars upfront but run higher monthly bills and need replacing within a couple of years. A traditional hot tub costs more both upfront and monthly, but offers durability and permanence in exchange. A Softub sits in a distinct middle ground: a moderate upfront cost, the lowest verified monthly operating cost of the three, and a build quality designed to last years rather than seasons. For the full side-by-side on installation and upfront pricing as well, see our complete Softub versus traditional hot tub comparison.
What Actually Drives the Cost Difference
Three factors determine how much any hot tub costs to run: insulation quality, heater efficiency, and how well the unit holds heat when not in use. Traditional hot tubs lose the insulation battle to their larger, less efficient shells. Inflatable spas lose it to thin, single-layer walls. Softub's foam interior and insulated cover are built specifically to minimize heat loss, which is the real reason its monthly number stays so far below either alternative.
The Bottom Line
If minimizing monthly operating cost is the priority, a Softub delivers the lowest verified running cost of the three main hot tub categories, without the durability tradeoffs that come with an inflatable spa's low sticker price. For coastal Rhode Island homeowners comparing all three, the numbers make a Softub the clearest long-term value.