Hot tub running cost calculator
Price measured hot tub energy use or a measured heater and pump schedule.
After you calculate
See your hot tub running costs
Add your hot tub energy use, operating days and electricity price, then calculate to see your results.
Heating cost
Shown after calculationElectricity needed
Shown after calculationEnergy use
Cost breakdown
Full calculation
The estimate follows your selected operating and heating scenario.
Understand your estimate
How it works
Estimate the electricity cost of running your hot tub. Choose either a measured daily total or a heater and pump schedule. These are two ways to describe the same daily use; do not enter the measured total and then add the same heater use again.
For a measured total, use a meter record or maker estimate that matches the water temperature, cover and use you plan. For a schedule, collect heater power, enabled hours, the share of those hours it actually heats, pump power and pump hours.
Enter all operating days, including days the tub stays warm between uses. You can also estimate one heating from a starting temperature to a target temperature. That separate figure helps explain a fresh fill; it is not automatically a repeated daily cost.
A few good questions
Before youget started.
Understand this calculator, the figures to enter and the limits of your estimate.
Sources
- Energy price cap unit rates and standing chargesChecked on 9 October 2026
- Australian Government: calculate appliance energy costsChecked on 13 October 2026
- CDC: healthy hot tub useChecked on 13 October 2026
- Pahlen: historical theoretical water-heating formulaChecked on 14 October 2026
- Last checked
- 13 October 2026
- Rates as of
- 1 October 2026
EnergySums
Hot tub running cost calculator
United Kingdom · How it works
- Guide updated
- 13 October 2026
- Rates as of
- 1 October 2026
| Item | Value |
|---|---|
| Guide updated | 13 October 2026 |
| Rates as of | 1 October 2026 |
How it works
Estimate the electricity cost of running your hot tub. Choose either a measured daily total or a heater and pump schedule. These are two ways to describe the same daily use; do not enter the measured total and then add the same heater use again.
For a measured total, use a meter record or maker estimate that matches the water temperature, cover and use you plan. For a schedule, collect heater power, enabled hours, the share of those hours it actually heats, pump power and pump hours.
Enter all operating days, including days the tub stays warm between uses. You can also estimate one heating from a starting temperature to a target temperature. That separate figure helps explain a fresh fill; it is not automatically a repeated daily cost.
Formula
Daily electricity is measured total kWh, or heater kW × hours × heating-on share plus pump watts ÷ 1000 × hours. Annual cost uses entered operating days. Heat needed for one water-heating event = 1.16 × water volume in m³ × temperature rise; electrical energy divides by entered heater efficiency. Do not add warm-up twice to measured totals.
Use a percentage as a fraction once: for example, 50% means 50 ÷ 100 = 0.5. Use 0.5 in the energy formula; do not divide it by 100 again.
The running-cost results repeat the entered day over your chosen operating days. Read the one-off heating result separately. If a measured day already includes that heating, adding it again would count the same energy twice.
Check power and energy units before entering them. Heater power is in kilowatts, pump power is in watts, and measured daily energy is in kilowatt-hours. A daily energy reading is not an hourly power rating. For the warm-up option, enter the volume being heated and both water temperatures, rather than yearly top-up water or the air temperature.
Worked example
These illustrative inputs are separate from your saved answers. Prices, use and performance are held constant for this worked scenario; they are not personal defaults.
Inputs used in this worked example.
- Electricity price
- My bill rate
- Electricity unit price
- 30 p / kWh
- Energy information available
- Measured daily electricity
- Operating days per year
- 365 days
- Measured total tub electricity
- 10 kWh / operating day
- Estimate the cost to heat the water once?
- Add a separate warm-up estimate
- Water volume
- 1200 L
- Starting water temperature
- 10 °C
- Target water temperature
- 38 °C
- Electrical heater efficiency
- 100 %
- Price conversion
- 100 pence or cents per currency unit
| Item | Value |
|---|---|
| Electricity price | My bill rate |
| Electricity unit price | 30 p / kWh |
| Energy information available | Measured daily electricity |
| Operating days per year | 365 days |
| Measured total tub electricity | 10 kWh / operating day |
| Estimate the cost to heat the water once? | Add a separate warm-up estimate |
| Water volume | 1200 L |
| Starting water temperature | 10 °C |
| Target water temperature | 38 °C |
| Electrical heater efficiency | 100 % |
| Price conversion | 100 pence or cents per currency unit |
- Cost / year
- £1,095.00
- Average / month
- £91.25
- Cost / operating day
- £3.00
- Cost to heat the water once
- £11.69
| Item | Value |
|---|---|
| Cost / year | £1,095.00 |
| Average / month | £91.25 |
| Cost / operating day | £3.00 |
| Cost to heat the water once | £11.69 |
- Daily input energy
- 10 metered kWh= 10 kWh
- Annual cost
- 10 kWh/day × 365 days × (30 p/kWh ÷ 100 p/GBP)= £1,095.00
- Initial water heating
- 1.16 kWh/(m³·°C) × (1,200 L ÷ 1,000 L/m³) × (38 − 10) °C= 38.976 kWh heat
- Warm-up electricity
- 38.976 heat kWh ÷ (100 ÷ 100)= 38.976 kWh
| Calculation | Formula with saved values | Result |
|---|---|---|
| Daily input energy | 10 metered kWh | 10 kWh |
| Annual cost | 10 kWh/day × 365 days × (30 p/kWh ÷ 100 p/GBP) | £1,095.00 |
| Initial water heating | 1.16 kWh/(m³·°C) × (1,200 L ÷ 1,000 L/m³) × (38 − 10) °C | 38.976 kWh heat |
| Warm-up electricity | 38.976 heat kWh ÷ (100 ÷ 100) | 38.976 kWh |
Assumptions and limits
Use metered daily electricity or documented heater and pump inputs for your operating schedule. The heating-on share allows for a heater switching off while it remains enabled. Use 100% when the entered power already describes an average over the whole entered time.
One measured day does not show every season. A different cover, water temperature, weather or use can change actual energy use. The estimate repeats your chosen conditions and does not predict those changes.
The separate warm-up figure covers the stated water volume and temperature rise. It excludes ongoing heat loss. Electrical heater efficiency is a percentage, not a heat pump COP. Money is rounded for display; totals use unrounded values.
Country rules
For the UK version, use the electricity price on your bill, including applicable tax. The selected published price is a dated reference and may differ from your tariff. Check the price period shown with the result.
Use the same price units as the field. Daily or monthly supply charges are outside this equipment-use estimate. A measured day is useful only when its water temperature, cover, weather and use match the scenario you want to price.
When to ask a professional
Water must not exceed 40°C. Follow official health guidance and the maker instructions. This tool gives no chemical dosing advice and does not decide a safe temperature for an individual person.
Ask the maker or a qualified installer if you are unsure about heater power, pump operation or the type of heater fitted. Use an appropriate qualified professional for electrical changes. Keep the meter record and equipment details used in your estimate.
Questions and answers
| Question | Answer |
|---|---|
| Where do I get the input figures? | Use the actual electricity/fuel bill, smart-meter or inverter record, installer assessment/quote or manufacturer technical sheet. The help explains the units and boundaries; do not guess an unavailable coefficient. |
| What does the calculation include? | Daily electricity is measured total kWh, or heater kW x hours x heating-on share plus pump watts / 1000 x hours. Annual cost uses entered operating days. Heat needed for one water-heating event = 1.16 x water volume in m³ x temperature rise; electrical energy divides by entered heater efficiency. Do not add warm-up twice to measured totals. |
| Is this a prediction or an assessment? | It calculates the entered scenario. Use metered daily electricity or documented heater and pump inputs for your operating schedule. |
| How are missing figures handled? | Complete the required fields using your bill, equipment records or an installer assessment. Enter 0 only where a quantity is zero or a cost does not apply. |
Sources
| Source | Checked | Reference URL |
|---|---|---|
| Energy price cap unit rates and standing charges | 9 October 2026 | https://www.ofgem.gov.uk/information-consumers/energy-advice-households/get-energy-price-cap-standing-charges-and-unit-rates-region |
| Australian Government: calculate appliance energy costs | 13 October 2026 | https://www.energy.gov.au/households/energy-rating |
| CDC: healthy hot tub use | 13 October 2026 | https://www.cdc.gov/healthy-swimming/safety/what-you-can-do-to-stay-healthy-in-hot-tubs.html |
| Pahlen: historical theoretical water-heating formula | 14 October 2026 | https://www.pahlen.com/wp-content/uploads/2021/02/swimming_pool_electric_heaters.pdf |