How to Determine Your BOLT Score
Some of you know this feeling already. You're a few rounds into active breathwork and your fingers start to tingle, or the room gets a little lighter, a little farther away. That's your body reacting to a shift in carbon dioxide, and it's a normal part of the process. I wrote more about the full picture in CO2 and Breathwork: What's Actually Happening in Your Body, and touched on it again in this week's newsletter.
This post is the practical piece. A simple way to measure your own CO2 tolerance, called the BOLT score, and what to actually do with the number once you have it.
What Is the BOLT Score?
BOLT stands for Body Oxygen Level Test. It was popularized by Patrick McKeown, creator of the Oxygen Advantage method, as a way to measure how long your body can comfortably tolerate a buildup of carbon dioxide before the urge to breathe kicks in. Despite the name, it isn't really measuring oxygen. It's measuring your sensitivity to CO2, the actual trigger for your next breath.
The higher the number, generally, the calmer and more efficient your breathing tends to be day to day.
How to Measure Your BOLT Score
You don't need any equipment beyond a timer.
Take three normal breaths, in and out through your nose.
After your last exhale, pinch your nose closed.
Time yourself until you feel the first real urge to breathe, not the point where you're gasping or straining.
If your diaphragm twitches or jumps, you've gone past your first signal. Start over, and don't push for a bigger number.
The point isn't willpower. It's information. You're timing your body's actual signal, not how long you can white-knuckle through discomfort.
You can read more about the original method on Oxygen Advantage's site.
Why the Tingling Happens
That tingling or lightheadedness comes from something called respiratory alkalosis. Active breathwork moves air faster than your day-to-day breathing, which pushes more CO2 out of your body than it's used to losing. That shift changes your blood's pH slightly, and your nervous system reads it as a signal, sometimes felt as tingling in the hands or mouth, sometimes as a lighter, farther-away feeling in the head.
None of it means something is wrong. It means your CO2 tolerance has room to build. This is part of why we always say, don't push, don't strain. Come back to natural breathing if a sensation feels like too much. The BOLT score below is one way to track that tolerance over time.
If you want the deeper physiology behind this, including why CO2 matters as much as oxygen, I wrote a full breakdown in CO2 and Breathwork.
What a Good BOLT Score Looks Like
Most people who haven't done any breath training land somewhere around 20 seconds or below. According to McKeown, a BOLT score under 20 seconds is often associated with a blocked nose, disrupted sleep, or breathlessness during exercise. A score of 40 seconds and above is considered a marker of efficient, effortless breathing.
Improving your score isn't about chasing a number for its own sake. It's a way of tracking how your nervous system is settling over time, breath by breath.
Building Your Tolerance
A few things tend to move the number over time, in my own experience and in what I see with clients:
Regular nasal breathing, even outside of formal practice. (Diaphragmatic Breathing, Breath retention, gentle holds)
Consistent active breathwork sessions.
Slower, gentler daily breathing rather than shallow chest breathing.
Patience. This shifts gradually, not overnight.
If you're curious where you're starting from, try the test above before your next circle or session. Some of you check in with it every few months just to notice the shift.
Go Deeper
If you want to explore what your breath is teaching you, in your own body or in guiding others, the Activation Breathwork Certification Training is a three-month path built for real depth. We approach the training through a science-based, somatic, spiritual psychology, shamanic, and trauma-informed lens. We keep each cohort small on purpose, and payment plans are available. Book a discovery call.
