Flashing °C, °F or mode symbol (ready, or still measuring)
A blinking unit or mode symbol is the thermometer telling you what stage it is at. On most of the infrared thermometers read here it means ready, or not ready yet; on a stick thermometer it means the reading is still rising.
Check your thermometer’s manual — makers differ.
What it is for
Wait for the signal your manual describes before you measure or read the result. Beurer’s FT 90 and FT 95 manuals list a measurement taken while the forehead symbol is still flashing as an error: “Wait until the forehead symbol stops flashing.” Omron’s ET720 manual gives the same fix for a measurement taken before the unit is ready: “Wait until all the icons stop flashing.”
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
- The °C or °F sign, or a small forehead icon, blinking on the screen; on Braun’s No touch, three dashes.
- Names makers use
- Flashing °C or °F (Microlife); Flashing forehead symbol (Beurer FT 90 and FT 95); Flashing icons (Omron ET720); Three dashes --- (Braun No touch BNT 400)
Where makes differ
Flashing means different things. On Microlife’s IR 310 and NC 200 a flashing °C or °F icon means ready, and it flashes again when the thermometer is ready for the next reading. On Microlife’s MT 410 stick thermometer the °C flashes while it is still measuring, and Microlife says ten beeps and a steady °C mean the reading rose by less than 0.1°C in 5 seconds; for the armpit, Microlife says to wait at least 5 minutes regardless of the beep. On Beurer’s FT 90 and FT 95 it is the other way round: the forehead symbol flashes during the self-test, and the thermometer is ready when it stops. Braun’s No touch BNT 400 shows three dashes (“---”) when it is ready and close enough to the forehead.
What it does not mean
A flashing °C or °F is not a warning, and it does not mean the thermometer has switched units. A beep at the end is not a fever alarm by itself: Microlife and Braun use a different pattern of beeps for a fever.
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 4 makers’ own manuals and support pages, each fetched and read on the date shown:
- Microlife: Microlife Ear Thermometer IR 310 — instruction manual (IB IR 310 N-V10, revision 2024-09-13, PDF) — Control Displays and Symbols: Ready for measurement — when the unit is ready, the °C or °F icon keeps flashing and one beep is heard; Measurement complete — the reading is shown and the unit is ready again when the icon flashes again. Checked 2026-09-29.
- Microlife: Microlife NC 200 non-contact thermometer — instruction manual (IB NC 200-e N-V10, 2026-08-17, PDF) — Control displays and symbols: ready for measuring, the «°C» or «°F» icon keeps flashing while the mode icon is displayed; a 3 second countdown before each measurement. Checked 2026-09-29.
- Microlife: Microlife MT 410 digital stick thermometer — instruction manual (IB MT 410, revision 2025-07-03, PDF) — Using the thermometer: “the current temperature is continuously displayed and the «°C» symbol flashes. If the beep is heard 10 times and the «°C» is no longer flashing, this means that the measured increase in temperature is less than 0.1°C in 5 seconds”; armpit: wait at least 5 minutes, regardless of the beep. Checked 2026-09-29.
- Beurer: Beurer FT 95 non-contact thermometer — instructions for use (2021-06-22, PDF) — Error messages: “Measurement during self-test, device not yet ready for measurement. Wait until the forehead symbol stops flashing”; ready for another measurement when two short beeps sound and the forehead symbol stops flashing. Checked 2026-09-29.
- Beurer: Beurer FT 90 non-contact clinical thermometer — instructions for use (2021-06-22, PDF) — Error messages: measurement during self-test, “Wait until the forehead symbol stops flashing”; “When two short beeps sound and the forehead symbol stops flashing, the device is ready to take another measurement.” Checked 2026-09-29.
- Omron: Omron No-Touch Forehead Thermometer ET720 (MC-720-Z) — instruction manual (US, 5681249-5D, PDF) — The Icons and Error Messages: “Measurement before unit is ready. Wait until all the icons stop flashing.” Checked 2026-09-29.
- Braun: Braun No touch + forehead thermometer BNT 400 — instruction manual (Asia-Pacific, PDF) — How to use: “When the thermometer is ready and on or 2.5 cm (1 inch) away from the forehead a horizontal line of dashes (“---”) will appear on the screen.” Checked 2026-09-29.
Written in our own words; quotations are the makers’ wording.