Bar graph on a pulse oximeter (pulse bar)
The bar rises and falls with each pulse the oximeter detects, and how high it goes shows how strong and clean the signal is. It is a signal-quality gauge: a tall, regular bar means the oximeter has a good pulse to measure; a short or erratic one means the numbers are less trustworthy.
Check your oximeter’s manual — makers differ.
What it is for
Check it before you read SpO2 or PR. Microlife says of its OXY 300 and OXY 200 that “the height of the bar graph is an indication of the pulse and signal strength” and that the bar “should be greater than 30 % for a proper reading”. Masimo says of the MightySat that the pulse bar blinks with the pulse rate and that “the height of the pulse bar provides an assessment of the confidence in the measurement displayed”. If the bar stays low, warm the hand, keep still and try another finger.
These pages report what each maker’s manual says and quote it wherever health is involved. They do not diagnose anything, they are not medical advice, and they do not tell you whether an oxygen or pulse reading is right for you or what to do about it; only your own oximeter’s manual and your doctor or nurse can do that for the person you are looking after.
- What it looks like
- A column of blocks or a single bar beside the numbers that jumps up and down in time with the pulse.
- Names makers use
- Pulse bar (Beurer PO 30 and PO 45, Microlife OXY 300); Pulse Rate Bar (Beurer PO 60); Pulse Bar (Masimo MightySat Rx, when the waveform is off); Bar graph (Microlife OXY 200)
Where makes differ
What the height stands for is worded differently: Microlife calls it pulse and signal strength and gives a minimum, Masimo calls it confidence, and Beurer says the bar only shows the signal variation at the finger and not the strength of the pulse or circulation. On the Masimo MightySat the bar only appears when the waveform is switched off.
What it does not mean
It is not a battery gauge, and it is not a measure of how strong your heartbeat or circulation is: Beurer’s manuals say so in as many words.
Other symbols with the same shapes
Sources
No published standard we could check defines what a fingertip pulse oximeter’s display shows, so this meaning is taken from 3 makers’ own manuals and support pages, each fetched and read on the date shown:
- Microlife: Microlife OXY 300 fingertip pulse oximeter — instruction manual (IB OXY 300 N-V9, revision 2023-11-30, PDF) — “The height of the bar graph 5 is an indication of the pulse and signal strength. The bar should be greater than 30 % for a proper reading.”; explanation of symbols: 5 Pulse bar. Checked 2026-09-29.
- Microlife: Microlife OXY 200 fingertip pulse oximeter — instruction manual (IB OXY 200 S-V10, 2026-09-14, PDF) — The same statement for the OXY 200’s bar graph 4: greater than 30% for a proper reading. Checked 2026-09-29.
- Masimo: Masimo MightySat Rx fingertip pulse oximeter — operator’s manual (LAB-9121C, PDF) — MightySat Rx features, item 5: with the waveform off, “the pulse bar displays as a visual indicator with blinking that corresponds to the pulse rate”; its height assesses the confidence in the measurement. Checked 2026-09-29.
- Beurer: Beurer PO 30 pulse oximeter — instructions for use (2020-01-08, German/English, PDF) — Display description: 4. Pulse bar; neither the pulse wave nor the pulse bar allows the strength of the pulse or circulation to be evaluated. Checked 2026-09-29.
- Beurer: Beurer PO 45 pulse oximeter — instructions for use (2020-06-12, German/English, PDF linked from beurer.com) — Unit description: 4. Pulse bar, 6. Pulse wave. Checked 2026-09-29.
Written in our own words; quotations are the makers’ wording.