"Keith Nuttle" wrote in message
...
I live in central Indiana, and we have experienced daytime temperatures between
75 and 90 degrees with dew points of 55 to 65 degrees.

My pond has about 120 square feet of surface area.

Can someone give me an estimate, in gallons, of the evaporation during a day.

One cubic inch = 0.00432900431 US gallons

So, measure the drop in water level (in inches) after 24 hours and multiply the
result by the area of your pond (in square inches) then by 0.00432900431 US
gallons, and you'll have your answer.

For instance, my pond is 4 feet by 12 feet. On a typical hot summer day, I lose
anywhere from 0.25 inch, to 0.5 inch. Using the lower number, which is more
typical for my pond, I get

48 in x 144 in x 0.25 in x 0.00432900431 US gallons = 7.4805 gallons per day.