Pool, Spa & Water Treatment Chemistry calculator

Pool Evaporation Water Loss Calculator

Convert estimated evaporation depth over the pool surface into gallons per day for water-use and leak checks.

What this calculator does

  • Estimate evaporation loss from surface area, evaporation depth, and gallon conversion.
  • Use it to separate normal evaporation from possible leaks or to plan make-up water.
  • Turns pool surface area, daily evaporation depth, gallon conversion into a practical gal / day result for evaporation water loss.

Formula used

  • Evaporation loss = surface area x evaporation depth x 0.623 x exposure adjustment

Inputs explained

  • Pool surface area: Use water surface area, not deck area.
  • Daily evaporation depth: Use local weather estimate or bucket test result.
  • Gallon conversion: Use 0.623 gallons per square foot-inch.
  • Exposure adjustment: Adjust for cover use, wind, humidity, or indoor ventilation.

How to use the result

  • Use it when planning pool, spa, aquatics, service-route, or water-treatment chemistry adjustments.
  • Use the result for planning math only. Follow product labels, health codes, local regulations, test-kit instructions, chemical safety rules, and qualified pool operator guidance before dosing water.

Common questions

  • What is the evaporation water loss calculator for? Estimate evaporation loss from surface area, evaporation depth, and gallon conversion.
  • What numbers do I need for evaporation water loss? You need pool surface area, daily evaporation depth, gallon conversion, exposure adjustment. Use measured test results and the same pool, spa, tank, or treatment volume for every input.
  • How should I use the result? Use the result to check dose size, run time, flow, inventory, or operating cost before changing a treatment plan or purchase order.
  • What should I verify before acting? Verify water volume, units, chemical strength, product label directions, bather load, local code, and current test results. Retest after treatment and never mix incompatible chemicals.

Last reviewed 2026-05-12.