Pulse Oximeter vs Blood Pressure Monitor: What's the Difference? UK Guide
A pulse oximeter and a blood pressure monitor measure different things. A fingertip pulse oximeter estimates blood oxygen saturation (SpO2) and displays pulse rate. An upper-arm blood pressure monitor measures the pressure of blood in your arteries and often also shows pulse rate. Neither device can replace clinical assessment, and one cannot substitute for the other.
Pulse oximeter vs blood pressure monitor: quick comparison
| Question | Pulse oximeter | Blood pressure monitor |
|---|---|---|
| What does it measure? | Estimated oxygen saturation (SpO2) and pulse rate | Systolic and diastolic blood pressure, often pulse rate |
| Where is it used? | Usually a fingertip | Usually the upper arm with an inflatable cuff |
| Typical units | SpO2 as a percentage; pulse in beats per minute | Blood pressure in mmHg; pulse in beats per minute |
| Can it measure blood pressure? | No | Yes |
| Can it measure oxygen saturation? | Yes, as an estimate | Not with a standard upper-arm blood pressure monitor |
What does a pulse oximeter measure?
A pulse oximeter uses light through the finger to estimate how much haemoglobin in the blood is carrying oxygen. It also displays a pulse rate. The Spinegear Finger Pulse Oximeter product listing describes a compact fingertip device that displays SpO2 and pulse rate. It does not measure systolic or diastolic blood pressure.
Pulse oximeter readings can be affected by factors such as movement, poor circulation, nail products and skin pigmentation. The UK Medicines and Healthcare products Regulatory Agency (MHRA) has warned that some pulse oximeters may overestimate oxygen levels in people with darker skin. Do not use a reading alone to decide whether symptoms are serious. If you are breathless, unusually drowsy or becoming unwell, seek appropriate medical help.
What does a blood pressure monitor measure?
A digital upper-arm blood pressure monitor inflates a cuff to estimate systolic and diastolic pressure, reported in millimetres of mercury (mmHg). Many models also display pulse rate. The Spinegear AXD-808 Rechargeable Upper-Arm Blood Pressure Monitor listing confirms a 22–42 cm cuff, USB-C charging, voice guidance and two-user memory with up to 99 readings per user. It is a home blood pressure monitor, not a pulse oximeter or 24-hour clinical ambulatory recorder.
For guidance on measuring and interpreting blood pressure, see the NHS high blood pressure information. Readings need to be interpreted in context, often using repeated measurements.
Why do both devices show pulse rate?
Pulse rate is the number of heartbeats detected per minute. A pulse oximeter estimates it from the changing light signal at the finger; a digital cuff monitor can derive it during a blood pressure measurement. The readings may differ because they are measured at different moments and with different techniques. A displayed pulse does not mean the devices measure the same health parameter.
Which device do you need?
For blood pressure checks
Use an appropriate blood pressure monitor and a cuff that fits. Follow advice from your GP or pharmacist on how often to check and what readings mean. See our blood pressure cuff size guide.
For oxygen saturation checks
A pulse oximeter can provide an estimated SpO2 reading, but its limitations matter. If you have been asked to monitor oxygen levels because of a medical condition, follow the specific instructions and escalation thresholds given by your healthcare team. See our pulse oximeter use guide.
For concerning symptoms
Do not delay seeking help to collect more numbers. Severe breathing difficulty, chest pain or signs of a medical emergency require urgent action. Call 999 in the UK for life-threatening symptoms. The NHS shortness of breath guidance explains when to seek emergency or urgent help.
Common mistakes to avoid
- Assuming an SpO2 percentage is a blood pressure reading.
- Assuming a normal-looking oxygen reading rules out a serious illness.
- Using an incorrectly sized blood pressure cuff.
- Comparing pulse readings taken at different times as though they were simultaneous.
- Changing medication based only on a consumer device reading without professional advice.
Frequently asked questions
Can a pulse oximeter detect high blood pressure?
No. A standard fingertip pulse oximeter does not measure blood pressure.
Does a blood pressure monitor show blood oxygen?
No. A standard digital upper-arm blood pressure monitor reports blood pressure and often pulse, not SpO2.
Why might the pulse readings differ?
Measurements may occur at different times, and movement, circulation and device technique can affect the result. Seek clinical advice about persistent or concerning irregularities.
Are these devices enough to diagnose a condition?
No. Readings are pieces of information; diagnosis and treatment decisions require clinical context.
Related guides
- Why Do Pulse Oximeter Readings Change?
- Common Blood Pressure Monitor Mistakes
- 24-Hour Blood Pressure Monitor vs Home Monitor
This article is general information and not a substitute for personalised medical advice.
