Pulse oximeters explained: what your SpO2 reading means

A fingertip pulse oximeter shines light through your finger to estimate how much oxygen your blood is carrying (SpO2) and your pulse rate.

Getting a good reading

• Warm your hands first: cold fingers reduce blood flow.
• Remove nail polish or artificial nails from the finger you use.
• Rest your hand on your chest or a table and stay still for at least 10 seconds.
• Wait for the number to settle before reading it.

What affects accuracy

Movement, poor circulation, bright light and very dark nail polish can all affect readings. Research also shows some oximeters can be less accurate on darker skin tones, so trends over time are more useful than a single number.

When to seek help

If you feel short of breath, have chest pain or feel confused, seek medical help immediately, whatever your oximeter reads.

This article is general information, not medical advice.