7 in Morse Code: −−···
The number 7 in Morse code is −−···, spoken as "DAH-DAH-di-di-dit": two long, then three short. Like every Morse digit it uses exactly five elements, so once you know the counting rule you can read any number without memorizing it.
Timing: how long each part lasts
Morse timing is built from one unit, the length of a dot. A dash is 3 units, and the silence between the elements of a single character is 1 unit. At 20 words per minute, one unit is 60 ms, so 7 breaks down like this:
| Element | Signal | Length (units) | At 20 WPM |
|---|---|---|---|
| Dash | − | 3 | 180 ms |
| Gap | (silence) | 1 | 60 ms |
| Dash | − | 3 | 180 ms |
| Gap | (silence) | 1 | 60 ms |
| Dot | · | 1 | 60 ms |
| Gap | (silence) | 1 | 60 ms |
| Dot | · | 1 | 60 ms |
| Gap | (silence) | 1 | 60 ms |
| Dot | · | 1 | 60 ms |
| Total for 7 | 13 | 780 ms | |
How to signal 7
- Tap it: two long, then three short. A short is a quick tap; a long is a heavier tap, or a quick tap followed by a slight hold, about three times as long.
- Blink it: two long, then three short. Use quick blinks for dots and slow, deliberate eye closes for dashes, keeping the rhythm steady.
- Flash it: two long, then three short. Short flashes for dots; for dashes, hold the light on about three times longer. Any flashlight or phone screen works.
Why the pattern makes sense
Every digit from 0 to 9 is exactly five elements long. For 1 through 5, count the dots at the start: the digit is the dot count, and dashes fill the rest. For 6 through 0, count the dashes: the digit is five plus the dash count (with 0 as five dashes). For 7: Two dashes (7 minus 5), then three dots.
7 opens '73', the classic goodbye between operators. It also sounds like Z with one extra dot on the end, another common speed trap.