Independent reference. The source material is available free from CDC. This page is not endorsed by CDC, HHS, or the U.S. Government.
How to use this classifier
- Choose 0–10 effort when you want a quick personal comparison. Select 0 for the effort of sitting and 10 for maximal effort, then read only the CDC band shown.
- Choose Talk test when speaking is a more useful cue. Select the statement that describes what you can say while the aerobic activity is happening.
- Use the result as a momentary description. The same activity can feel different to people with different fitness levels, and it can feel different to the same person on another day.
What the two references mean
Relative intensity asks how hard the activity is for the person doing it. CDC gives two named ranges on its general 0–10 comparison: moderate at 5 or 6, and vigorous beginning at 7 or 8. This page treats 7 through 10 as vigorous and deliberately leaves 0 through 4 unnamed instead of inventing extra labels.
The talk test is a separate rule of thumb on the same CDC page. Talking but not singing points to moderate activity. Being able to say only a few words before pausing for breath points to vigorous activity. It does not measure oxygen use, diagnose breathing trouble, or prove that a particular workout is safe.
Examples
During a brisk walk, a person selects 5 and can talk but not sing. Both references point to moderate intensity for that moment. The result describes perceived effort; it does not prescribe speed, duration, incline, or weekly minutes.
During a run, a person selects 8 and can only speak a few words before pausing. Both references point to vigorous intensity. If the number and talk cue disagree, record the observation rather than forcing a medical conclusion.
Important limits
- The 0–10 buttons are a plain presentation of CDC’s general anchors and bands. They do not reproduce Borg wording, instructions, trademarks, or a licensed Borg chart, and this page does not claim equivalence to a Borg scale.
- This guide does not use symptoms, heart rate, medication, disability, pregnancy, age, diagnosis, or fitness-test results. It gives no target zone, load, pace, exercise choice, training plan, or return-to-activity advice.
- Stop using the page as a classifier if you need help for pain, faintness, chest symptoms, unusual breathlessness, injury, or another health concern. Seek an appropriate clinician or emergency service based on the situation; the page cannot assess urgency.
Exercise intensity FAQ
Is 5 always moderate for everyone?
The CDC number is relative effort. It describes how hard the activity feels to the person, so the same external task can produce a different rating for someone else.
Why are 1–4 not labeled light?
The cited CDC comparison explicitly names 5–6 as moderate and says vigorous begins at 7–8. This page avoids adding a band that the assigned source did not define.
Is this a Borg RPE scale?
No. It does not reproduce the Borg RPE or CR10 instructions or verbal anchors and does not claim validation as either scale.
Can I use this to choose a workout?
It can help describe an activity, but it does not prescribe a workout, duration, weight, pace, or progression.
Does the choice leave my device?
No. The interaction runs in the browser and adds no account or storage.