Pool Evaporation Calculator — Gallons and Refill Time

Live calculator

Enter your measurements

Water-surface length

Measure across the waterline, not outside coping or walls.Water-surface width

Surface shape factor

Use 100% for a rectangle or 78.54% for a true ellipse measured across full axes.Uncovered daily evaporation

in/day

Enter an evaporation-only local estimate or controlled benchmark, not total unexplained water loss.Planning period

days

Entered cover reduction

Use a documented or scenario value; zero represents the entered uncovered benchmark.Measured refill flow

gal/min

Measure flow at the actual hose, valve, or fill outlet.Optional local water rate

$/1,000 gal

Use the applicable marginal water rate; add sewer or other charges separately when they apply.

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