Training load calculator
Session RPE calculator — training load, monotony and strain
Write down a week of sessions with a duration and a 1–10 rating of how hard each one felt. The grid prices every session in Foster's arbitrary units, adds the week up day by day, and gives you the monotony and strain figures on top. Edit any row. Free, instant, no sign-up.
Your training week
Rate the whole session, once, about half an hour after it finished — not during it, and not one number per interval. Warm-up and cool-down count in the duration. Two sessions on the same day add together into one daily load.
Load by day
A day with no session is a zero in this row, not a gap. It goes into the mean and into the standard deviation like every other day — leave the rest days out and a well-varied week starts to look flat.
Monotony here divides by the population standard deviation — squared deviations over n, with n = 7 — because the seven days are the whole week being described rather than a sample of it. With the sample standard deviation (over n−1), which is what a spreadsheet's STDEV gives you, the same week reads 1.32.
A high weekly load together with high monotony is the combination Carl Foster associated with illness and injury in the original monitoring work. Read it as a flag to think about rather than a diagnosis: the studies behind it are small, and no monotony value predicts that anything will happen to a particular person in a particular week.
One week's load says little on its own — the coach watches how the total, and the shape, move from week to week.
The session RPE scale
Borg's category-ratio scale as Foster's group put it to athletes. Rungs 6, 8 and 9 carry no wording in the original — they are the spaces between the anchored ratings, and athletes use them exactly that way.
What is session RPE?
Session RPE prices a training session with the two numbers every athlete already has: how long it lasted, and how hard the whole thing felt. Around thirty minutes after the session ends — far enough away that the last hard interval no longer dominates the answer — the athlete rates it from 1 to 10 on Borg's category-ratio scale, and that rating is multiplied by the duration in minutes to give a load in arbitrary units. An easy 45-minute jog at RPE 3 is 135 AU; an hour of threshold work at RPE 8 is 480. Carl Foster published the method in 1998 in Medicine & Science in Sports & Exercise, and its whole point is that it costs nothing: no lab, no power meter, no chest strap, one question.
How this calculator works
Each session is priced at duration × RPE and rounded to whole units, then the sessions are summed day by day across the seven days of the week. Monotony is the mean of those seven daily loads divided by their standard deviation; strain is the weekly total multiplied by monotony. This page uses the population standard deviation — squared deviations divided by n, with n = 7 — on the grounds that a training week is the complete set of days you are describing, not a sample drawn from a larger pool. State that convention out loud, because sources differ and the difference is not small: a spreadsheet's STDEV is the sample form (divided by n−1), which for a seven-day week makes the standard deviation about 8% larger and the monotony about 8% smaller. Both figures are printed here so nobody has to guess which one they are reading.
Why rest days count as zero
A day with no session enters the calculation as a zero, not as a missing value, and that decision moves the answer more than most people expect. Take the week this page opens on: 1,815 AU across six sessions with Thursday off scores a monotony of 1.43. Throw the rest day out and average across the six days that had training in them, and the same week scores 1.90 — the mean rises, the spread collapses, and a properly varied week suddenly looks flat. Zeros are where the variation in a training week actually lives, so an implementation that quietly drops them is not computing the same statistic. If you are comparing this page against another tool and the monotony disagrees, check the rest days before you check anything else.
Logging session RPE so the numbers mean something
Ask for the rating once, for the whole session, about half an hour afterwards — rate it in the car park and the final effort colours the entire answer. Use the same verbal anchors every week, because the scale is only as consistent as the words attached to it, and rate the session you actually did rather than the one that was written down. Count warm-up and cool-down in the duration. Then treat the weekly total as a trend rather than a target: session RPE is at its most useful comparing this week to last week for the same athlete, and at its least useful comparing one athlete's number to another's, because the scale is calibrated inside one head at a time.