Pool Pump Run Time Calculator
Pool water is managed in turnovers, not in hours. A turnover is the time it takes for the whole body of water to pass through the filter once — volume divided by flow. Fifty thousand litres at 250 litres a minute is one turnover in 3.3 hours, so a target of one and a half turnovers a day means five hours of running. What is worth optimising here is not the hours but the watts: pump power rises with roughly the cube of flow, so halving the speed and running twice as long delivers the same turnover for about a quarter of the electricity. That single relationship is what pays for a variable-speed pump.
Your numbers
Run time a day
5h
Time for one turnover
3.3h
Energy a month
165kWh
What it means
Run it 5 hours a day, which comes to 165 kWh a month. Running slower for longer buys the same turnover for far less electricity.
Formula
Time for one turnover = Litres ÷ (Flow (L/min) × 60), Run time a day = Time for one turnover × Turnovers a day
The flow printed on a pump is measured with no plumbing resistance, so the real figure is lower — read the filter pressure gauge alongside a flow meter if you want the true number. A dirty filter drops flow further, which means the same run time quietly delivers less turnover, so the backwash interval belongs to this calculation too.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Litres (L)Capacity in litres; one litre is 1,000 cm³. | 50,000 | 0 and up |
| Flow (L/min) (L/min)How many litres the tap delivers each minute. | 250 | 0 and up |
| Turnovers a day (×)How many turnovers a day you are aiming for — the real standard, not hours. | 1.5 | 0 ~ 10 |
| Pump power draw (kW)The pump draw; it falls with roughly the cube of flow when you slow it down. | 1.1 | 0 and up |
Step by step
Quick reference table
Results when only Litres (L) changes and everything else stays put.
| Litres (L) | Run time a day (h) | Time for one turnover (h) | Energy a month (kWh) |
|---|---|---|---|
| 25,000 | 2.5 | 1.7 | 83 |
| 37,500 | 3.8 | 2.5 | 124 |
| 50,000 | 5 | 3.3 | 165 |
| 75,000 | 7.5 | 5 | 248 |
| 100,000 | 10 | 6.7 | 330 |
What each result means
| Result | At default values |
|---|---|
| Run time a day (h)The hours a day the pump must run to deliver that many turnovers. | 5 |
| Time for one turnover (h)How long the whole body of water takes to pass through the filter once. | 3.3 |
| Energy a month (kWh)A month of running at that schedule; multiply by your own tariff for the cost. | 165 |
Common mistakes
The flow printed on a pump is measured with no plumbing resistance, so the real figure is lower — read the filter pressure gauge alongside a flow meter if you want the true number. A dirty filter drops flow further, which means the same run time quietly delivers less turnover, so the backwash interval belongs to this calculation too.
Glossary
- Litres
- Capacity in litres; one litre is 1,000 cm³.
- Flow (L/min)
- How many litres the tap delivers each minute.
- Turnovers a day
- How many turnovers a day you are aiming for — the real standard, not hours.
- Pump power draw
- The pump draw; it falls with roughly the cube of flow when you slow it down.
- Run time a day
- The hours a day the pump must run to deliver that many turnovers.
- Time for one turnover
- How long the whole body of water takes to pass through the filter once.
- Energy a month
- A month of running at that schedule; multiply by your own tariff for the cost.
Frequently asked questions
Q. How is Pool Pump Run Time Calculator calculated?
Time for one turnover = Litres ÷ (Flow (L/min) × 60), Run time a day = Time for one turnover × Turnovers a day — Pool water is managed in turnovers, not in hours. A turnover is the time it takes for the whole body of water to pass through the filter once — volume divided by flow. Fifty thousand litres at 250 litres a minute is one turnover in 3.3 hours, so a target of one and a half turnovers a day means five hours of running. What is worth optimising here is not the hours but the watts: pump power rises with roughly the cube of flow, so halving the speed and running twice as long delivers the same turnover for about a quarter of the electricity. That single relationship is what pays for a variable-speed pump.
Q. Can you walk through an example?
With Litres 50,000L, Flow (L/min) 250L/min, Turnovers a day 1.5×, Pump power draw 1.1kW, the answer is Run time a day 5h.
Q. What do I need to enter?
Enter Litres, Flow (L/min), Turnovers a day, Pump power draw. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Litres (L) moves the answer to Litres (L) 25,000 → Run time a day (h) 2.5 and Litres (L) 100,000 → Run time a day (h) 10. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
The flow printed on a pump is measured with no plumbing resistance, so the real figure is lower — read the filter pressure gauge alongside a flow meter if you want the true number. A dirty filter drops flow further, which means the same run time quietly delivers less turnover, so the backwash interval belongs to this calculation too.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.