This article is from the Aerobics Fitness FAQ, by oaktree@shell.urjet.net (Robles) with numerous contributions by others.
The Borg scale of perceived exertion is another way of
determining how hard you are working. Using your own
subjective Rate of Perceived Exertion (RPE) on a scale of
6-20 or a scale of 0-10, you determine how hard you *feel*
you are working. A rating of 12-16 ("somewhat hard" to
"hard" on the 12-20 scale) or a rating of 4-6 ("somewhat
strong" to "very strong") on the 0-10 scale
reflects a heartrate of 60-90% of maximum and should be the
target area for which to strive.
Original Scale Revised Scale 6 0 Nothing at all 7 Very, very light 0.5 Very, very weak 8 1 Very weak 9 Very light 2 Weak 10 3 Moderate 11 Fairly light 4 Somewhat strong 12 5 Strong 13 Somewhat hard 6 14 7 Very strong 15 Hard 8 16 9 17 Very hard 10 Very, very strong 18 * Maximal 19 Very, very hard 20
 
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