Pool running cost calculator: what does my pool cost per month?

There is no honest single answer to what a pool costs per month, because the biggest lines — electricity, gas and water — are priced locally and change through the season. What you can do is add up your own lines. This calculator does that, one cost at a time, so you can see which one is worth attacking.

How the running cost calculator works

pump = watts × hours a day × 30 ÷ 1,000 × price per kWh
heating = kWh × price per kWh, or therms × price per therm, or gallons of propane × price per gallon
chemicals = what you spend in a month
top-up water = surface (sq ft) × inches lost a week × 0.623 gal × 30 ÷ 7 × price per gallon
  (metric: m² × cm a week × 10 L × 30 ÷ 7)
salt cell = watts × pump hours × 30 ÷ 1,000 × price per kWh

A month here is 30 days. Water lost to evaporation and splash-out is entered as inches (or cm) of level a week; one inch over one square foot is 0.623 gallons, and one centimetre over a square metre is 10 litres.

Where the numbers come from

• Pump. Power × hours. DOE’s Florida example pool used 3,000 kWh a year on pumping before changes; a smaller pump and fewer hours together cut that by 75%. The pool pump cost calculator goes deeper, including a variable-speed comparison.
• Heating. Enter the energy your heater uses in a month. If you don’t know it, the pool heating cost calculator estimates it from your pool, temperatures and heater, and the pool heater vs heat pump guide compares fuels.
• Chemicals. Your own receipts are the only reliable figure. The dose calculators — chlorine, salt, acid — turn your test results into amounts you can price.
• Water. Top-ups replace evaporation, splash-out and backwash. SNWA’s Las Vegas average is 48.6 gallons per square foot a year, about 1.5 in a week — a hot, dry desert; most places lose less. The pool evaporation calculator works it through.
• Salt cell. A salt chlorine generator draws power while it runs, usually with the pump. Its spec sheet gives the watts; the salt itself is a once-a-season cost, from the pool salt calculator.

A worked example

The page on how much it costs to run a pool per month works through an example budget line by line, with what changes the total most. Its numbers are examples too; the point is the method.

Where the savings are

1. Pump hours and speed. Usually the biggest line without a heater. DOE suggests starting at 6 hours of filtration a day; ENERGY STAR notes that halving pump speed uses one-eighth the energy.
2. A cover. DOE: 50%–70% off heating, 30%–50% less make-up water, 35%–60% less chemical. SNWA says covers reduce evaporation by 90%.
3. Water temperature. DOE notes each degree of extra temperature costs 10%–30% more in heating energy.
4. Chemistry by test, not habit. Dosing to a test result rather than a routine avoids buying chlorine and acid the water didn’t need. The pool running costs guide has more.