Ballpark — April 21, 2026
Answers to that day's 5 daily estimation questions.
Tennis balls used during the Wimbledon tournament
55,000 balls
New balls are provided every few games.
About how much does a gallon of water weigh?
8.34 lb
A gallon of water is about 8.3 pounds.
About how many liters can a typical grocery shopping cart hold?
~150 L
A full-size grocery cart holds on the order of a hundred liters.
About how many times does a person breathe in a day?
~20,000 breaths/day
Breathing adds up fast—often around twenty thousand breaths per day.
What temperature is an average household refrigerator set to?
~37 °F
Many fridges are set just above freezing to keep food safe.