How to Send Morse Code with a Flashlight
Morse code was made for light: how to flash SOS and any message with a flashlight or phone torch, with the exact timing that keeps it readable.
Before radio, Morse code travelled by light — naval signal lamps blinked messages between ships for over a century, and they still work when everything else fails. A flashlight, a phone torch or a bedroom lamp is all you need to send a message tonight.
The timing that makes it readable
Light follows exactly the same rules as sound. A dit is a short flash of one unit; a dah stays on for three units. Inside a letter, leave one unit of darkness between flashes; between letters, three units; between words, seven. Keeping the dark gaps honest matters more than speed — a rushed gap merges two letters into a different one.
| Element | Light | Length |
|---|---|---|
| Dit (·) | short flash | 1 unit |
| Dah (–) | long flash | 3 units |
| Gap in a letter | darkness | 1 unit |
| Gap between letters | darkness | 3 units |
| Gap between words | darkness | 7 units |
Flashing SOS, step by step
- Three short flashes — S (· · ·).
- Three long flashes — O (– – –).
- Three short flashes again — S. Pause for a few seconds, then repeat.
- Aim at your target and keep the rhythm steady: steady and slow beats fast and ragged.
SOS is sent as one continuous prosign — no letter gaps — which is what makes it instantly recognisable. Read the full story in SOS in Morse code.
Use your phone as a signal lamp
Our free Morse code translator has a built-in lamp that flashes any message in perfect time while the tone plays — type it, press play, and hold the screen where it can be seen. It is the easiest way to learn light timing, because you can copy a machine that never rushes its gaps.
A century of blinking ships
Navies still train signalmen on Aldis lamps: directional lights with a trigger that shutter Morse across miles of open water, no electronics to jam or intercept. The skill survived radio for a simple reason — light is silent, private to the line of sight, and works in radio blackout.
Frequently asked questions
What is SOS with a flashlight?
Three short flashes, three long, three short — · · · – – – · · · — with a clear pause before repeating. In an emergency, any repeated group of three signals is also a recognised distress pattern.
How fast should I flash?
Slower than feels natural. Aim for a dit of about half a second while learning; whoever is reading needs your dark gaps far more than your speed.
Which letters are easiest to send by light?
E (one short), T (one long) and S/O. Learn the rest with the full Morse code alphabet — every character has audio you can flash along to.
