A human (~adult) heart pumps between 60 and 90ml of blood each contraction, so a good average would be anywhere from #70# to #80ml# to use in calculation. I'll use #75#, though it would vary with age, person, and instantaneous exertion, presumably.

Take your resting heart rate in beats per minute. Take it a few times and find the average for the most accurate value.

Do the calculation

#T = 60 * V * r #,

where #T# is the total blood pumped, #V# is the volume per pump (#75# in this approximation, #r# is resting heart rate and #60# is for the number of minutes you want.

With units, this is

#T ml = 60min * V(ml)/(beats) * r (beats)/(min)#,

so the #min# and #beats# units cancel, leaving only #ml#.

Say your resting heart rate is #80 (beats)/(min)#, then the total blood pumped in one hour is approximately

#T approx 60 * 75 * 80 = 360,000ml = 360L#