The cost to run a wood fired hot tub in the UK typically ranges from £5 to £20 per session, depending on your wood source, tub size, starting water temperature, and weather conditions. There are no electricity costs and no standby draw—you only spend money when you actually use it, making wood-fired running costs genuinely competitive with electric alternatives for most households.
There's no single honest answer to the question "how much does it cost to run a wood fired hot tub?"—and anyone who tells you otherwise is probably guessing. If you're a homeowner or potential hot tub buyer trying to judge affordability before you buy, or trying to compare a wood-fired tub with an electric one, the real figure depends on how cold the water starts, how windy it is, the size of your tub, what wood you're burning, and whether you remembered to put the cover on during heating (more on that later).
What we can do is give you realistic ranges, show how wood use and heating times affect the price of each soak, and help you work out your own per-session cost with a few practical ways to keep it down. By the end of this, you'll have a clear sense of what to expect, how to estimate your running costs, and whether a wood fired hot tub makes financial sense for the way you actually plan to use it.
What "running costs" actually covers
Before the numbers, it helps to know what you're actually paying for. For a wood fired hot tub, that's:
- Wood — the main variable, and the one that matters most
- Kindling and firelighters — a small but real cost, usually £1–2 per session if you're not splitting your own
- Water — you'll top up occasionally and do a full refill every few weeks or so depending on use; at UK tap rates, a full refill of a typical 1,000–1,500-litre tub costs around £1–3
- Basic water care — wood-fired tubs don't need the same chemical regime as electric spas, but a simple routine is sensible if you're keeping the water for more than a couple of sessions
- Maintenance — minimal; a good tub needs very little beyond the odd clean and firebox check, check our blog for more
No electricity bill. No standby draw. No annual service contract. That simplicity is a big part of the appeal.
Wood fired hot tub heating time and cost: what to expect per soak
A typical wood fired hot tub takes 2–4 hours to reach soaking temperature, with summer sessions at the shorter end and cold-weather fills pushing towards (and occasionally beyond) the upper limit.
Here's what makes the difference:
- Starting water temperature — filling from a cold tap in January versus a warm tap in July can easily add an hour to your heat-up time
- Target temperature — most people aim for 38–40°C; going beyond that just burns more wood for no real benefit
- Wind — this is the sneaky villain. A breezy evening will bleed heat from even a well-insulated tub; a simple windbreak or a sheltered spot makes a noticeable difference
- Lid use — keeping the cover on while you heat makes a genuine dent in both time and wood use. It's the single easiest win going
A practical example: on a mild autumn day with a winter-cold fill (around 12°C), you're looking at roughly 3 hours to hit 39°C, with moderate wood consumption. On a warm summer evening starting at 18–20°C, you might be in within 90 minutes.
How much wood to heat a wood fired hot tub?
For a typical 4–6-person wood fired tub, expect to use somewhere in the region of 15–25kg of seasoned hardwood per session, though the range is genuinely wide. Smaller tubs need less; larger tubs and colder conditions need more.
The type of wood matters a lot here:
- Seasoned or kiln-dried hardwood (oak, ash, birch) burns hotter, cleaner, and more efficiently — you'll use less of it and get a faster heat-up
- Wet or green wood burns poorly, produces excessive smoke, and leaves you burning twice as much for half the result. It's frustrating in practice and costs more over time
- Softwood ignites easily and is fine for getting the fire going, but burns fast; hardwood is what does the sustained heating work
Our honest guidance: buy the driest hardwood you can afford, especially if you're buying in bags, because it is usually your main fuel cost. If you've got a log store and some patience, buying a bulk bag in spring (when prices are typically 20–30% lower), splitting larger logs for easier handling and more efficient burning, and letting it season further is one of the most cost-effective moves you can make.
What affects costs the most — and how we'd keep them down
Use seasoned hardwood. It's the single biggest lever. Wet wood doesn't just slow things down — it costs you more in volume burned.
Put the cover on during heating. Sounds obvious but it's easily forgotten. The heat loss through an uncovered tub is significant, so a good cover helps hold the right temperature more efficiently.
Find a sheltered spot or add a windbreak. Wind is a heat thief. Even a fence panel or hedge between the tub and the prevailing breeze makes a real difference.
Don't overheat. There's no award for reaching 44°C. Most people find 38–40°C perfect, and once you hit your desired temperature, chasing higher temps just burns more wood for diminishing returns.
Plan back-to-back sessions. If two of you want a soak and then friends are coming over later, don't let the tub cool completely between rounds. Topping the temperature up is far cheaper than heating from cold twice in a day.
Buy wood in bulk, off-season. Kiln-dried hardwood in bags from a garden centre can run to £8–15 per bag at peak winter prices. Ordering a large bulk bag (around 200kg) from a specialist supplier in spring typically costs £90–120 — and that single order covers a good number of sessions at a fraction of the per-bag rate.
Is a wood-fired hot tub cheaper than electric to run?
This is probably what you actually came here for, so let's look at it properly.
Electric models use an electric heater plus other electrical components like pumps and filtration systems, which adds convenience but also ongoing power demand.
For installation, electric hot tubs need a reliable electrical connection and power source, which can mean additional cost, while wood-fired tubs can work well in places that do not require electricity.
Some buyers prefer electric tubs for a steady temperature, automation, jets, and additional features; others prefer the simpler wood-fired setup.
The honest read: electric tubs look convenient because they're always warm — but that constant temperature maintenance is where the real cost sits. A 3–6kW heating element running at the standard UK electricity rate of around 24–28p per kWh adds up fast, especially across autumn and winter, and how much electricity they use often works out at roughly £500 to £1,200 per year.
A wood fired tub only costs money when you use it. If you're soaking two or three times a week with good-quality hardwood bought in bulk, annual wood spend for moderate use is often around £200 to £600, and your annual running cost might still sit comfortably below what an equivalent electric tub spends on electricity alone — before servicing and chemicals or other features a modern heater setup may support.
The quick maths: estimating your per-soak cost
Here's a simple way to work out your own number:
- Estimate your wood use — around 15–25kg is a useful starting point for a standard tub
- Work out your cost per kg — bulk bag hardwood typically works out to 45–65p per kg; retail bags are higher
- Add £1–2 for firelighters/kindling
- Add around £1–2 for water (unless you're doing a fresh refill, in which case closer to £2–3)
So a mid-range session using 20kg of bulk-bought hardwood at 55p/kg looks something like: £11 wood + £1.50 firelighters + £1.50 water = roughly £14 per session. Buy well and keep the cover on, and you can comfortably get that below £10.
Frequently asked questions
How long does a wood fired hot tub take to heat in winter?
In cold conditions, expect 3–4 hours from a cold fill to soaking temperature (38–40°C), with wood-fired tubs commonly heating at around 3ºC to 6ºC per hour in winter conditions. Starting with warmer water, keeping the lid on during heating, and sheltering the tub from wind all reduce that time meaningfully, though the exact process depends on stove type and external temperature.
What's the best wood to use in a wood fired hot tub?
Dense, seasoned hardwoods — oak, ash, and birch are the most widely recommended — burn hotter, longer, and more cleanly than softwoods or wet wood. If you’re using larger logs, split them down first so they catch faster and burn more efficiently in the stove. Kiln-dried hardwood with moisture content below 20% is the most consistent and efficient option for most UK buyers.
Do wood fired hot tubs need chemicals?
A basic water care routine is sensible, but wood fired tubs don't require the intensive chemical management that electric spa systems often do. Many owners simply drain and refill every few sessions; if you keep water for more than a couple of sessions, regularly check pH levels to maintain water quality, while others use a light treatment regime to extend water life between changes.
How often do I need to change the water?
This depends on how frequently the tub is used and whether any water treatment products are being used. For occasional use without filtration, draining and refilling every few sessions (or after a weekend of use) is the simplest approach.
Can I reduce smoke from a wood fired hot tub?
Yes. Smoke is mainly a sign of wet or low-quality wood. Switching to kiln-dried hardwood and ensuring the fire has enough airflow reduces smoke significantly. Softwood and green wood are the most common culprits.
Is a wood fired hot tub cheaper than an electric one to run?
For most UK households using the tub a few times a week, yes — especially once you factor in the standby electricity costs of maintaining an electric tub at temperature around the clock. Electric tubs can take several hours to reach the desired temperature from cold, but they are easier to keep steady once heated. Wood-fired tubs use a more natural heating process through a wood burning stove and water circulation system; to avoid colder pockets, you may need to circulate water manually. They also do not use gas, pumps, or other powered systems unless you choose a hybrid setup. Wood fired running costs are use-dependent, which gives you much more control over your spending.
Final verdict: so, is it expensive?
Wood fired hot tub running costs are more controllable than most people expect. The biggest swings come from wood quality and sourcing — get those right, and the per-session cost is genuinely reasonable. Add a decent cover, pick a sheltered spot, and plan your sessions with a bit of intention, and you're looking at a running cost that competes very favourably with electric.
It also helps that the whole ritual — lighting the fire, watching the temperature climb, sitting outside while the steam rises — doesn't really feel like a cost at all, especially as part of the appeal is the natural thermosiphon process, where the stove heats the water and it circulates without pumps. More like an excuse to stand in the garden pretending you're somewhere much more remote, with the sound of a crackling fire in the background.
If you're weighing up the numbers and you like the idea of a hot tub powered by fire (and a certain kind of calm), take a look at our wood fired hot tub range and find the setup that suits your space.