Pool fill time calculator
How long a pool takes to fill at a known flow rate.
Fill in the fields and the result will appear here automatically.
Takes the volume — given directly, or from the dimensions of a rectangular or round pool — converts it to litres and divides by the flow. Exactly three shapes are supported, the ones that actually come up; an arbitrary basin will not fit here, and the calculator does not pretend otherwise.
How it works
Formula and logic
Known volume V is in m³; rectangular basin V=L×B×h and cylindrical round basin V=π×(D/2)²×h. Convert flow to L/min: L/h÷60, m³/h×1000÷60. Time t=1000 V/F minutes; hours=t/60. The hours/minutes row rounds total t first, then splits whole hours and remainder 0..59. Depth is active only for the two dimension modes.
Example
A 32 m³ pool at 20 litres per minute takes 1600 minutes, or about 26.7 hours. 0.596 m³ at 10 L/min takes 59.6 min; the rounded row is 1 h 0 min.
Fields and units
- Pool shape — list option
- Volume, m³ — m³
- Length, m — m
- Width, m — m
- Diameter, m — m
- Depth, m — m
- Flow rate — in the selected volume-flow unit
- Flow unit — list option
How to use
- — Choose whether you know the volume or the dimensions.
- — Enter the figures for that shape.
- — Enter the flow rate and pick its unit.
Method and limitations
- Calculation method
- Formula and logic
- Limitation
- Known volume V is in m³; rectangular basin V=L×B×h and cylindrical round basin V=π×(D/2)²×h.
FAQ
Where do I find the flow rate?
Fill a bucket of known volume and time it. A garden hose and a mains supply differ by several times, so measuring beats guessing.
Should I measure the depth I actually fill to?
Yes. Pools are rarely filled to the brim, and the water line is what determines the volume.
Are other shapes supported?
No, only a known volume, a rectangle and a circle. An oval or freeform basin would need a geometry the calculator does not have.
Does the flow stay constant in practice?
Not necessarily: pressure, hose and other users can change flow. The formula assumes the constant entered rate and omits evaporation, leaks and additional sources. Its time may be below or above the actual duration.