A fingertip pulse oximeter shines light through your finger to estimate blood oxygen saturation (SpO2) and pulse. Sit still, warm your hands, remove nail polish, and wait for a steady reading. Cold fingers, movement, nail polish and, as the FDA has noted, darker skin pigmentation can affect accuracy. Use readings alongside symptoms, and contact a doctor about low readings or breathing difficulty.
A pulse oximeter is a useful home check when used correctly.
Getting an accurate reading
| Step | Why |
|---|---|
| Rest for 5 minutes | Movement affects readings |
| Warm your hands | Cold fingers reduce blood flow |
| Remove nail polish | It can block light |
| Use the index or middle finger | Common recommended fingers |
| Wait for a steady number | Readings settle after a few seconds |
Accuracy limits
The FDA has communicated that skin pigmentation, poor circulation, skin thickness and temperature can affect pulse oximeter accuracy. Look at trends and symptoms, not one number.
When to call a doctor
Low readings, a falling trend, or symptoms such as breathlessness, confusion or chest pain. Call emergency services for severe symptoms.
Compare with smartwatch SpO2, and see OTC glucose monitors. Browse home monitors.
Common questions
What is a normal SpO2 reading?
Many healthy people read around 95 to 100 percent. Your doctor can tell you what is normal for you, especially with lung or heart conditions.
Are cheap oximeters accurate?
Accuracy varies. Look for FDA-cleared prescription or over-the-counter devices, and note that some low-cost devices are sold for sports or wellness only.
Should I rely only on the oximeter?
No. Symptoms such as shortness of breath or chest pain matter more. Seek care if you feel unwell.