Borg Scale 6 to 20: What Each Number Means

The Borg scale runs from 6 to 20 because it was built to shadow heart rate, not because 6 is a natural floor for anything. Verbal anchors sit at specific numbers, and those anchors — not the digits — are what makes one person’s 15 comparable to another’s.

The anchors, rating by rating

• 6 to 8 — no exertion at all, up to extremely light. Sitting, standing, strolling to the kitchen. Nothing you would call exercise.
• 9 to 10 — very light. An easy warm-up walk. You could keep it up for hours.
• 11 to 12 — light. Breathing is up a little and you notice you are moving, but talking is completely unaffected.
• 13 to 14 — somewhat hard. The workhorse of exercise prescriptions. Effort is obvious, you can still hold a conversation, and you could sustain it for a long session.
• 15 to 16 — hard, or heavy. Talking comes in short sentences. This is where most people find their tempo running or a solid interval.
• 17 to 18 — very hard. Sustainable only in bouts, with real concentration required to keep going.
• 19 — extremely hard. Almost everything you have, and not for long.
• 20 — maximal exertion. The stopping point.

The wording belongs to Gunnar Borg and is licensed through Borg Perception; the anchors are described here for reference rather than reproduced as the clinical form. To turn a rating into a training zone, use the Borg RPE scale calculator — that page is the tool, this one is the reference.

What people actually report

Two findings are worth carrying around. First, the top of the scale is emptier than it looks: using the national FRIEND registry of exercise tests, ACSM researchers found that mean and median peak ratings across sex, age and test mode landed between 18 and 19, and 83% of participants reported 18 or higher at the end of a maximal test. A rating of 20 is not the normal ending; 18 or 19 is.

Second, the middle of the scale lines up with measurable physiology. In a cohort of 2,560 adults doing incremental treadmill and cycle tests, the lactate threshold corresponded to an average rating of 10.8 and the individual anaerobic threshold to 13.6. Fixed lactate concentrations of 3 and 4 mmol/L landed at 12.8 and 14.1. That is why “13 to 14” keeps appearing in guidance rather than some rounder number.

Reading a rating honestly

Ratings drift. The same effort feels heavier when you slept badly, when it is hot, when you are under-fueled, and lighter when you are fresh and motivated. That drift is not noise to be corrected — it is the signal, because it reflects the cost of the session to you on that day, which no pace or wattage figure captures.

What does undermine a rating is instruction. The scale assumes you were told to judge the whole body’s effort, not just how hard your legs burn or how loud your breathing is. Read the anchors before your first few sessions and the numbers settle down quickly.

For the 0 to 10 version used in lifting, intervals and whole-session scoring, see the modified Borg CR10 scale. For the version tuned to walking in later life, see the RPE scale for seniors.