Ohm symbol
The ohm symbol Ω is electricity’s unit of resistance — the Greek capital omega, borrowed to honour Georg Ohm, whose law (V = I × R) runs every circuit ever built. Copy Ω here with its scaled family (mΩ, kΩ, MΩ), the values it labels on resistors and speakers, and the story of its secret twin, the dedicated ohm sign Ω.
Copy the ohm forms
Ohm values ready to copy
Reading resistance values
| Scale | Meaning | Where you meet it |
|---|---|---|
| mΩ (milliohm) | A thousandth of an ohm | Cable and contact resistance, battery internals |
| Ω (ohm) | The base unit | Speakers (4 Ω, 8 Ω), heating elements, sensors |
| kΩ (kilohm) | A thousand ohms | Most resistors in electronics: 1 kΩ, 4.7 kΩ, 10 kΩ |
| MΩ (megohm) | A million ohms | Insulation testing, multimeter input resistance |
Two characters claim to be the ohm. The everyday one is Greek capital omega Ω (U+03A9) — the SI itself writes the unit with omega. Unicode also keeps a separate OHM SIGN Ω (U+2126), a legacy character that looks identical and is treated as equivalent; documents use omega almost everywhere, and either pastes fine — just know the twin exists when a spec sheet insists on it.
How to type it
| Platform | Method |
|---|---|
| Windows (Word) | Type 3A9 then Alt + X (2126 for the dedicated ohm sign) |
| Mac | Option + Z gives Ω on the standard layout |
| HTML | The “Omega” entity name (ampersand + Omega;) or code 937; the ohm sign is code 8486 |
| Multimeters & labels | The Ω is printed on the dial — for notes and reports, copy it from here rather than typing a look-alike O |
Explore more
The letter’s own home is the Greek alphabet, its unit colleagues gather in the unit symbols, and the law it serves is written with the multiplication symbol inside the wider math symbols.
Frequently asked questions
What does the ohm symbol measure?
Electrical resistance: how strongly a material or component opposes current. One ohm is the resistance that lets one amp flow under one volt — Ohm’s law, V = I × R, ties the three together, and R is always written in Ω.
Is Ω just the Greek letter omega?
Yes — the unit borrowed the capital omega wholesale when the ohm was standardised in the 1860s–70s, honouring Georg Ohm’s name with a Greek O. The same glyph moonlights as the ohm in physics and as a letter in Greek text; context decides which job it is doing.
Ω or Ω — which should I copy?
Ω (Greek omega, U+03A9) for practically everything: it is what the SI uses and what every font carries. The separate ohm sign Ω (U+2126) exists for legacy data; the two are canonically equivalent, so nothing breaks if one is swapped for the other.
Why do resistors say 4K7 instead of 4.7 kΩ?
Print survives better than decimal points on tiny components: the letter replaces the point and carries the scale at once — 4K7 = 4.7 kΩ, 1M0 = 1.0 MΩ, and 0R5 = 0.5 Ω (R for the base unit itself).