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Hot Tub Monthly Running Cost Calculator

Reviewed for 2026, updated September 8, 2026.

Estimates what a luxury hot tub costs to run each month and per soak, for owners and buyers comparing electricity, chemicals and refills.

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Results update as you type.

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Monthly electricity...
Total monthly running cost...
Total annual running cost...
Cost per soak...

Estimates only. Assumptions are listed below, and you can change every input.

The purchase price of a premium hot tub is only the opening line of the budget. The number that decides whether you enjoy it or resent it is the recurring one: the electricity to hold 400 gallons at 102 degrees through a winter, the sanitizer and filters, and the quiet cost of draining and reheating fresh water several times a year. Most brochures skip that arithmetic. This calculator does it for you.

You enter your spa's typical daily energy use, your utility rate, what you spend on chemicals, the water volume and how often you drain it. The tool multiplies daily electricity by an average month, adds the energy needed to reheat each refill from cold tap water, and spreads the result across a year and across your soaks. It is an honest estimate, not a utility bill: efficient insulation, a tight cover and a mild climate will push you below it, and a poorly covered tub in a northern January will push you above it.

How to use this tool

  1. Enter your spa's daily electricity use in kWh and the all-in rate from your utility bill.
  2. Add what you spend on chemicals and filters in a typical month, then the water capacity and how many times a year you drain it.
  3. Set how often you soak to see the cost of each session, and compare two spas by changing only the daily kWh figure.

What the math assumes

  • A month is treated as 365 divided by 12 days, so monthly electricity is daily use multiplied by 30.42.
  • Each refill is assumed to be reheated from 55 F tap water to 102 F, a rise of 47 F, using 8.34 pounds per gallon and 3,412 BTU per kWh at 100% heater efficiency.
  • Fresh water for refills is priced at 8 USD per 1,000 gallons including sewer charges unless your utility differs; it is a small part of the total.
  • Daily electricity use is taken as a year-round average; real use rises in cold months and falls in warm ones.
  • Cost per soak divides the annual total by soaks per week multiplied by 52; it does not add wear or depreciation.

Frequently asked questions

How do I find my hot tub's daily electricity use?

Start with the manufacturer's published energy figure, often expressed as kWh per day or a monthly dollar estimate at a stated rate. For an installed spa, a plug-in energy meter on a 120 V model or a clamp meter reading on a 240 V circuit gives a real number over a week.

Why does the calculator add energy for every water change?

Heating a full tub from cold tap water takes far more energy than maintaining temperature, so four refills a year add a noticeable line to the budget. The tool estimates that heat separately so it is not hidden inside the daily average.

Does this include the purchase price or servicing?

No. It covers only the recurring running costs of electricity, chemicals and refills. For the full picture over several years, use the total cost of ownership calculator on this site.

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