Unofficial totals say Oak Park had the most rain of any Chicago-area community over the 18-hour period between 6 p.m. Friday and noon Saturday. Wednesday Journal scientists have been hard at work crunching numbers to figure out just how much rain really fell.

Assuming the 8.33 inches of rain fell evenly over Oak Park’s 4.5 square miles during those 18 hours we made these calcuations.

1 mile = 5280 feet
1 square mile = 27,878,400 square feet
1 square foot = 144 square inches
1 liquid gallon = 231 cubic inches

Total area of Oak Park = 4.5 square miles
Total rainfall  = 8.33 inches

4.5 square miles  X  27,878,400 square feet = 125,452,800 square feet
125,452,800 square feet  X  144 square inches = 18,065,203,200 square inches
18,065,203,200 square inches of surface in Oak Park  X  8.33 inches = 150,483,142,656 cubic inches of rain
150,483,142,656 cubic inches of rain ÷ 231 cubic inches = 651,442,176 gallons

Measured in snow, Oak Park’s 8.33 inches of rain would total out to 80 inches, or just shy of 7 feet of fluffy white stuff.

651,442,176 gallons, how to get your mind around that number?

  • Oak Parkers consume 9 million gallons per day during the summer
  • Total water reservoir capacity in Oak Park is 10 million gallons
  • An Olympic swimming pool holds 666,000 gallons

Chime in with your own calculations and comparisons.

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Graham Johnston

Graham Johnston is manager of Internet and technology at If you ever ask Graham about his job the first thing he'll tell you is that he's worked at the same company since he was 10 years old....