Three near-identical circle-and-line marks that decide whether a device is asleep, off, or genuinely disconnected. The differences are a gap in a circle and whether the line is inside or crossing it.
Look at the circle. A circle with a gap and a line crossing it is standby — the device stays connected to its supply. A closed circle with the line inside is a true on/off toggle. A plain circle with no line at all means power is actually disconnected. Most consumer 'power buttons' are the standby symbol, which is why unplugging still matters.
| Standby symbol | Power on/off toggle symbol | Power off symbol | |
|---|---|---|---|
| IEC reference | IEC 60417-5009 | IEC 60417-5010 | IEC 60417-5008 |
| Visual difference | Broken circle with a line crossing the gap | Closed circle with the line inside it | Plain circle, no line at all |
| Is power actually disconnected? | No — the equipment stays connected to its supply | Yes, in the off position — it toggles fully on and fully off | Yes — this position disconnects power |
| Where you see it | Most consumer device power buttons, remote controls, monitors | Single buttons that genuinely switch fully on and off | The 'O' half of a rocker or toggle switch marked |/O |
| Common misconception | That pressing it turns the device off. It selects a low-power state; standby draw continues | That it is the same symbol as standby — the closed circle is the whole difference | That any circle means off. Only the plain circle does; a circle with a line is standby |
| Relationship (from Symbolwise's records) | Commonly confused with Power on/off toggle symbol — Near-identical: a broken circle means standby, a closed circle means a true on/off toggle. The difference is a gap a few pixels wide but changes whether power is actually disconnected.; Commonly confused with Power off symbol — Routinely read as 'off', but this symbol leaves the equipment connected to its supply — the plain circle is the one that means power is genuinely disconnected. | Commonly confused with Standby symbol — Near-identical: a closed circle means a true on/off toggle, a broken circle means standby. Only the second actually disconnects nothing. | Commonly confused with Standby symbol — A plain circle means power is genuinely disconnected; the standby symbol's circle-with-a-line does not disconnect power at all. |
IEC 60417's registry entries give each symbol's reference number, title and scope, which is what these rows state. The full normative text is paywalled and is not reproduced — see docs/paywalled-standards.md.
IEC 60417 graphical symbols for use on equipment — Online Browsing Platform entries
ISO/IEC Online Browsing Platform · retrieved 2026-07-29
The official registry confirms each symbol's reference number, title and scope of application, which is what Symbolwise cites. The full normative text and the exact drawing geometry are behind the standard's paywall and are deliberately not reproduced.
Wikipedia · retrieved 2026-07-29
Secondary. Used for the IEC 60417 reference numbers, the quoted definitions, the Unicode codepoints and the 1973 IEC 417 date. The standard text itself is paywalled and was not consulted.
Alpha is a Greek letter and stands for a quantity — an angle, a coefficient, a significance level. The proportionality sign is an operator and stands between two quantities to say they keep a constant ratio. The drawings differ in that the proportionality sign's right-hand stroke runs out in an open curve rather than closing into the letter's tail.
Look at the left-hand edge. A straight flat back is an AND gate: the output is true only when every input is. A curved concave back is an OR gate: true when any input is. Everything else about the shapes is similar, which is why the back edge is worth checking deliberately rather than at a glance.
Equal-length lines mean a capacitor. Alternating long and short lines mean a battery, with the long line positive. If the second line is curved rather than straight it is a polarised capacitor — still a capacitor, but one that must be fitted the right way round.
Look at the pattern. Even short dashes throughout is a hidden line: an edge that exists but is concealed behind material. Long dashes alternating with dots is a centre line: an axis of symmetry or the centre of a circle, which is not a physical edge at all. Reading a centre line as an edge is the commonest beginner's error on a drawing.