A healthy blood oxygen level (SpO2) is typically 95% to 100% for most people. Levels below about 92%–94% may warrant medical attention, especially if you have symptoms or a known lung or heart condition. Newborns have slightly different expectations (often 90%–95% initially, then rising toward 95%–100%). Key points to know

• How it's measured: Pulse oximetry (noninvasive) gives a percentage SpO2; arterial blood gas (ABG) testing provides a more precise PaO2 value if needed.
• What’s normal by context:
  • General healthy adults and children: 95%–100% SpO2.
  • People with lung or heart disease: 92%–94% may be acceptable to some extent, but should be discussed with a clinician.
  • Newborns: early readings can be 90%–95%, then typically rise to 95%–100%.
• What to do if low:
  • Acute readings <92% or accompanying symptoms (shortness of breath, chest pain, confusion) require prompt medical evaluation.
  • If you have a chronic lung disease and notice a drop, contact your healthcare provider for guidance on your individual target range and any need for supplemental oxygen.

If you’d like, share your age, health conditions, and whether you’re using a pulse oximeter or have recent ABG results, and I can help interpret where your readings fall relative to typical targets and what steps to consider.