Key takeaways
— Infrared: about 1–2 kWh per session — single-digit dollars per month at daily use.
— Electric traditional: 6–12 kWh per session including heat-up — roughly $15–25/month at four sessions a week.
— Wood-fired: the cost is firewood and ritual; electricity's share is zero.
Sauna running costs get discussed like folklore — everyone's brother-in-law has a number. The arithmetic is simpler: watts, hours and your local rate. Here it is, worked through honestly.
The three bills, worked out
An infrared cabin draws about 1.9 kW. A forty-minute session including warm-up is roughly 1.5 kWh — at a typical $0.15–0.30/kWh, call it 25 to 45 cents per session. Daily use lands in single digits per month.
An electric traditional room draws 6–10.5 kW, and the heat-up is where the meter spins: 35–45 minutes of preheat plus the session totals 6–12 kWh. Four sessions a week works out to roughly $15–25 a month in most markets — an honest number worth knowing, and rarely the number that decides the purchase.
Wood-fired rooms bypass the meter entirely. Their currency is firewood — a few split logs per session — and the half-hour of fire-tending that owners describe as a feature.
What actually moves the number
Insulation is the multiplier nobody prices in: a well-insulated room reaches temperature faster and cycles the heater less. Session habits matter too — back-to-back household sessions amortize one heat-up across several bathers. And climate is a factor outdoors: a −20° January asks more of the stove than a mild October evening. Your quote includes an estimate against your actual local rate.
The per-session arithmetic, honestly done
An 8 kW electric heater running a ninety-minute session — forty-five minutes of climb, forty-five of thermostat-controlled hold — draws roughly 8 to 10 kilowatt-hours. At typical North American residential rates of twelve to twenty cents per kilowatt-hour, that is one to two dollars per session. A three-round family evening might reach twelve kilowatt-hours: still under two fifty at most rates, or roughly the cost of the coffee you skipped to be there.
Monthly, the arithmetic stays gentle: three sessions a week lands between fifteen and thirty dollars on the power bill — comparable to a streaming bundle, for a habit with considerably better outcomes. Infrared cabins run lighter still: a 1.8 kW draw over a forty-minute session is under a single kilowatt-hour, pennies in any market, which is why the Infrared Pro's operating cost rounds to invisible.
Wood-fired rooms trade electrons for logs: an armful of dry hardwood per session, which is either a few dollars purchased or effectively free from a managed woodpile. The honest total cost of wood heat is the labour — and owners consistently file that under recreation rather than expense.
What actually moves the bill: insulation, habits, climate
Between two identical heaters, the operating cost difference lives in the envelope. A well-insulated room holds its temperature between rounds with the elements barely cycling; a thin-walled build re-earns its heat continuously, and the meter records the difference all winter. This is the unglamorous reason our builds carry multi-layer insulation — the purchase-day spec that discounts every session for decades.
Habits move the number almost as much: pre-heating for exactly the time needed rather than an idle hour, keeping the door closed between rounds, and running scheduled starts instead of speculative ones each shave real percentages. The barrel's geometry is the structural version of the same discipline — less volume, less energy, same session.
Climate sets the baseline: winter sessions in cold regions cost a third or so more than summer ones, and an outdoor build in Winnipeg simply works harder than the same room in Vancouver. The sizing conversation in your quote accounts for this — the right heater in the right envelope keeps even the coldest market's sessions in the low single dollars.
Total cost of ownership: the five-year view
Zoom out from the per-session pennies and the five-year ledger stays friendly. Energy: perhaps a thousand to fifteen hundred dollars across five years of steady family use. Consumables: stones every couple of years, gaskets once, cleaning kits twice a year, oil if you keep the finish — a few hundred dollars total, all parts-counter items. Maintenance labour: yours, measured in pleasant minutes.
Set that against what the sauna displaces — spa visits, wellness memberships, the recovery modality subscriptions the household no longer needs — and most owners' ledgers cross into positive territory before year three. Add the property-value line that a permanent, warranted outdoor room contributes, and the honest summary is the one we opened with: the sauna's purchase price is the whole story; the running of it is a rounding error with health benefits.
Comparing running costs across our line
Ranked by operating cost per session, the line runs: Infrared Pro (pennies — a sub-kilowatt-hour session), the barrel saunas (the efficiency champions of true löyly, their reduced volume shaving every climb), the cabins and indoor rooms (the formula's honest middle, one to two dollars), and the wood-fired options (free-to-cheap in money, priced in pleasant labour). The Fortis, for all its glass, holds the cabin band — its insulation was specified against exactly this ledger.
The cold side barely registers: the plunge chiller's insulated duty cycle draws refrigerator-class power, and the wood-fired hot tub's fuel is the same woodpile as the stove's. A complete contrast setup — sauna plus plunge, run three evenings a week — lands under fifty dollars a month in most markets, which is less than one family spa visit and available in bathrobes.
The comparison that matters most is the one buyers rarely run: against the wellness spending the sauna replaces. Households that tally their pre-sauna spa, recovery-studio, and massage line items against the new power bill almost universally find the sauna cash-positive within the first year — the rare luxury purchase that runs a surplus.
Reading your own meter: a one-month experiment
For the empirically minded, the definitive answer costs nothing: note the meter before and after a standard session (or watch the smart-meter app's hourly graph), multiply by your rate, and own the real number for your room, your climate, your habits. Run the same reading in January and July and the seasonal spread appears; run it before and after fixing a tired door gasket and the maintenance chapter of this journal justifies itself in kilowatt-hours.
Owners who run the experiment report two consistent reactions: first, the number is smaller than they assumed — the myth of the power-hungry sauna dies hard; second, the measuring habit spreads, and the household's whole energy picture improves as a side effect. The sauna, once again, quietly improving things it was never asked to.
The bottom line
One to two dollars per electric session, pennies for infrared, an armful of wood for the stove — and a five-year total that most households recoup from the wellness spending it replaces. The sauna is the rare luxury whose running costs need no defending: measure yours once, smile at the number, and get back to the bench. The expensive part of sauna ownership is the years you waited to start.
One caveat on rates
All figures here use typical North American residential rates; time-of-use markets reward scheduling sessions off-peak (the Wi-Fi controller's quiet superpower), and European rates shift the absolute numbers while leaving every comparison intact. Whatever your tariff, the structure of the answer survives: insulation decides the bill, habits trim it, and the total stays in coffee-budget territory for any household that would notice.
Postscript
And if the meter experiment surprises you pleasantly — as it will — the correct response is one more session a week, which remains the best-value line in the entire household budget.