The ohm is written with capital omega Ω, the Greek letter at U+03A9. Unicode does have a separate ohm sign at U+2126, but it advises against using it, and normalisation converts it to the Greek letter anyway. Type 03A9 then Alt+X in Word.
01 All shortcuts at a glance
| Platform | Shortcut | |
|---|---|---|
| Windows (any app) | Win+. or Win+; emoji/symbol picker, or Character Map (Win+R → charmap) |
|
| Mac | Control+Command+Space to open Character Viewer, search "Greek Capital Letter Omega" |
|
| Word / Outlook | Type 03A9, then press Alt+X |
|
| Linux (IBus) | Ctrl+Shift+U, then 03a9, then Enter |
|
| HTML / CSS | Ω · \03a9 (CSS) |
02 Step by step, per platform
A real, followable procedure for every platform, not a thin restatement of the shortcut.
Windows
- Open Character Map: Win+R, type charmap, press Enter.
- Search or scroll for Greek Capital Letter Omega (U+03A9).
- Select it, click Copy, then paste where you need it.
Mac
- Press Control+Command+Space to open the Character Viewer.
- Type "Greek Capital Letter Omega" in the search field.
- Double-click the result to insert it.
Microsoft Word
- Type 03A9.
- Press Alt+X immediately after, it converts the hex code to Ω.
03 Characters in this set
04 Troubleshooting & confusables
| Looks like it | But it's actually | When to use |
|---|---|---|
| Ω (U+2126) | The deprecated ohm sign | Kept only for compatibility with older encodings. Prefer the Greek capital. |
| ohms spelled out | The unit name in words | Correct in running prose. The symbol belongs with a figure, as in 470 Ω. |
| R in a value code | A decimal point substitute on components | Resistor markings write 4R7 for 4.7 Ω, keeping the value readable without a dot. |
05 FAQ
Which character should I use for ohms?
The Greek capital omega at U+03A9. Unicode explicitly recommends it over the ohm sign at U+2126, which exists only for compatibility.
Why does the ohm sign exist at all?
It was inherited from older character sets that encoded it separately. Unicode keeps it for round-trip conversion, and normalisation folds it into U+03A9.
What is an ohm?
The SI unit of electrical resistance, named after Georg Ohm. One ohm passes one ampere when one volt is applied across it.
Is there a space before the symbol?
Yes. SI style puts a space between the number and the unit, as in 470 Ω, and preferably a non-breaking one so the pair never splits.
What is the symbol for kilohms and megohms?
kΩ and MΩ, with the standard SI prefixes. Note the capital M for mega and the lowercase k for kilo, which is a real distinction in SI.