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The ohm sign is a capital omega. Unicode encodes them separately, they are drawn identically, and only the context tells you which you are looking at.
If it sits after a number on a circuit diagram, a resistor or a rating plate, it is the ohm — a unit of electrical resistance. If it appears in a formula as a variable, it is the Greek letter, most often angular velocity in its lowercase form ω. The characters are visually identical in capital form, so position is the whole answer.
The ohm sign is the capital of this letter, encoded separately in Unicode and drawn identically. Whether a capital omega means resistance or the letter depends entirely on where it appears.
Drawn from the visual attributes recorded for each symbol. Only traits the two records disagree about are listed.
| Trait | Omega | Ohm sign |
|---|---|---|
| Built from | letter like and circles | letter like |
| Omega | Ohm sign | |
|---|---|---|
| What it is | The last letter of the Greek alphabet | A unit of electrical resistance |
| Where you meet it | In formulae, as a variable | After a number, on components and rating plates |
| Typical meaning | Angular velocity (ω), or an infinite ordinal | Resistance in ohms — 470Ω, 10kΩ |
| Unicode | U+03C9 lowercase, U+03A9 capital | U+2126, kept separate for compatibility |
| Relationship (from Symbolwise's records) | Commonly confused with Ohm sign — The ohm sign is the capital of this letter, encoded separately in Unicode and drawn identically. Whether a capital omega means resistance or the letter depends entirely on where it appears. | Commonly confused with Omega — This sign is the capital Greek letter omega, encoded separately in Unicode for compatibility. Whether a capital omega means resistance or the letter depends entirely on where it appears. |
Unicode Code Chart: Greek and Coptic (U+0370–U+03FF)
The Unicode Consortium · retrieved 2026-07-30
Authoritative for the character's code point, name and block only. Unicode assigns identity; it does not define what a symbol means in use.
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for the widely-agreed uses of the letter across fields and for its history. Not used to assert that any one use is the letter's definitive meaning — no body defines that, and the record says so.
Greek letters used in mathematics, science, and engineering
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for the widely-agreed uses of the letter across fields and for its history. Not used to assert that any one use is the letter's definitive meaning — no body defines that, and the record says so.
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