M, memory number or memory icon (a stored reading)
You are looking at a stored reading, not a new one. Some thermometers show the last reading by themselves when you switch them on, so the first number you see may be old.
Check your thermometer’s manual — makers differ.
What it is for
Before you trust a number, check that no M or memory icon is lit. Braun’s ThermoScan manual says the last temperature taken is shown automatically for 5 seconds when it is switched on again, and Microlife’s MT 410 manual says the last reading appears for 2 seconds with the M icon.
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 a temperature is a fever or what to do about it; only your own thermometer’s manual and your doctor or nurse can do that for the person you are looking after.
- What it looks like
- An M, sometimes with a number after it, or a small memory icon beside a reading.
- Names makers use
- M, M2 … (Braun ThermoScan); M and a reading number (Microlife); Memory icon (Omron ET720); Memory function (Beurer FT 90 and FT 95)
Where makes differ
Memory size differs: Braun’s ThermoScan 7 keeps the last 9 readings, Omron’s ET720 the last 25, Microlife’s IR 310 and NC 200 the last 30, and Beurer’s FT 90 and FT 95 the last 60, while Withings’ Thermo shows the last five from the past 72 hours on the thermometer itself. What gets stored differs too: Omron leaves out Hi and Lo results and deletes every reading when you switch between °F and °C, and Beurer stores only forehead readings. On Microlife’s MT 410 stick thermometer, holding the button for more than 3 seconds at switch-on shows the maximum temperature stored during the last measurement.
What it does not mean
M does not mean a new measurement or a mode. It is not the small second number Omron’s ET720 shows in the corner after a second reading, which is the reading taken just before.
Other symbols with the same shapes
Sources
No published standard we could check defines the symbols on a digital thermometer’s display, so this meaning is taken from 5 makers’ own manuals and support pages, each fetched and read on the date shown:
- Braun: Braun ThermoScan 7 (IRT 6520) and ThermoScan 3 (IRT 6030) infrared ear thermometers — instruction manual (Asia-Pacific, PDF) — Memory mode: “This model stores the last 9 temperature measurements”; the stored reading is shown with “M” (for example M2); “The last temperature taken is stored in its memory and will be automatically displayed for 5 seconds when it is turned on again.” Checked 2026-09-29.
- Microlife: Microlife MT 410 digital stick thermometer — instruction manual (IB MT 410, revision 2025-07-03, PDF) — Turning on: the last measurement reading is shown automatically for 2 seconds with the «M» icon; Storage of Measured Values: hold ON/OFF for more than 3 seconds to show the stored maximum temperature with «M». Checked 2026-09-29.
- Microlife: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, revision 2024-09-13, PDF) — How to recall 30 readings in Memory Mode: the memory icon shows; “Number «1» and a flashing M are displayed” for the last reading. Checked 2026-09-29.
- Omron: Omron No-Touch Forehead Thermometer ET720 (MC-720-Z) — instruction manual (US, 5681249-5D, PDF) — Using the Memory Function: “This unit automatically stores the last 25 measurement results (excluding Hi/Lo results)”; switching °F/°C deletes stored readings; after a second measurement the first is shown in the right corner. Checked 2026-09-29.
- Beurer: Beurer FT 95 non-contact thermometer — instructions for use (2021-06-22, PDF) — Displaying stored measurements: “The device only stores measurements in forehead temperature mode”, the last 60 measurements, with date and time. Checked 2026-09-29.
- Withings: Withings Thermo — user guide (v2.0, April 2018, PDF) — Viewing the history of my measurements: slide the touch-sensitive area; “You can see the last five measurements taken in the past 72 hours.” Checked 2026-09-29.
Written in our own words; quotations are the makers’ wording.