How many breaths does a person average each day?

12-16 beats per minute is average so...

720-960 beats per hour

17,280-23,040 per day

A normal respiratory rate is somewhere around 8-14 breaths per minute. Given 1,440 minutes in a day, and assuming a normal respiratory rate of say 12 breaths per minute, and that respiratory rate doesn't vary much throughout the day, you'd have 12 * 1,440 = 17,280 breaths in a day. Of course these assumptions break down when considering a real person doing real things (eg, what would happen in exercise?), the number at least gets you in the ballpark.

17,280-23,040 per day

The average person takes about 15 breaths a minute. So, 15 x 60 (minutes in an hour)= 900 x 24 (hours in a day) = 21,600.

Depending on the circumstances, the average person in- and exhales 12 times per minute 0.5 litres of air. 12 times 0.5 makes 6 litres of air per minute. Thus 60 times (1 hour) 24 times (1 day) 6 litres results in 8640 litres of air in 1 day. This is done in 17280 breaths per day.