95 to 100 percent is normal on a pulse oximeter, per MedlinePlus - with asterisks: chronic lung disease can set a lower personal baseline, and altitude lowers everyone's.
Act when readings drop below 92 percent, or when any low reading arrives with symptoms - breathlessness, chest pain, confusion, blue or grey lips - and severe symptoms mean 911 regardless of the number. Home-oximeter traps: nail polish blocks the sensor (use a bare finger), cold fingers read falsely low (warm first), movement scrambles readings, cheap devices vary - sit still, warm hand, bare nail, wait for steady. The rule that outranks the device: how you feel beats what it says. Pymander is a free AI doctor, 24/7 by text, and can help you judge a reading.
What to do
Common questions
What is a normal oxygen level?
A normal oxygen saturation - the number a pulse oximeter clips onto your finger to read - is 95 to 100 percent, per MedlinePlus. The asterisks: people with chronic lung disease (COPD, severe asthma) can run lower baselines that their doctors accept as normal for them, and altitude lowers readings for everyone. What the number means practically: it is the percentage of your hemoglobin currently carrying oxygen - your blood's delivery efficiency. When to act: a reading dropping below 92 percent, or any low-ish reading with symptoms - breathlessness, chest pain, confusion, blue or grey lips and fingernails - means medical attention now; severe symptoms mean 911 regardless of what the device says. The home-oximeter traps, because they are common: nail polish and artificial nails block the sensor's light (use a bare finger or a different site), cold fingers read falsely low (warm your hand first), movement during the reading scrambles it, and cheap devices vary in accuracy - sit still, warm hand, bare nail, and wait for a steady reading. And the rule that outranks the device: how you feel beats what it says - a person gasping with a 94 needs help, and a calm 93 without symptoms usually needs a recheck, not an ambulance. Pymander is a free AI doctor, 24/7 by text, that can help you judge a reading.