Å and Å are one of those Unicode pairs that can look perfectly identical. U+212B carries the historical name ANGSTROM SIGN; U+00C5 is the ordinary letter A WITH RING ABOVE. Unicode links them canonically and prefers Å for current text.
For the unit itself, the current SI Brochure lists the symbol Å and defines one angstrom as 10−10 m, or 0.1 nm. The interesting part is therefore not the size of the unit, but why a second Å-shaped code point exists at all.
Two ways an Å-shaped symbol can be encoded
| Form | Unicode identity | Code point | Role in modern text |
|---|---|---|---|
| Å | ANGSTROM SIGN | U+212B | Legacy encoded character |
| Å | LATIN CAPITAL LETTER A WITH RING ABOVE | U+00C5 | Preferred Unicode representation and angstrom unit symbol |
Why the special angstrom sign exists
Earlier character sets did not all represent the angstrom in the same way. Some had a dedicated symbol, while other systems used the ordinary letter Å. Unicode preserved U+212B so those older encodings could be converted without simply discarding their original character identity.
Unicode then linked U+212B to U+00C5 through canonical equivalence. Its Names List marks Å as the preferred representation. The dedicated code point therefore survives mainly for compatibility with legacy text, not because modern scientific writing requires a distinct angstrom character.
What normalization does to Å
Canonical normalization can replace Å with Å. The regular Å itself can also be represented in decomposed form as U+0041 LATIN CAPITAL LETTER A followed by U+030A COMBINING RING ABOVE.
So visually similar source text can begin from three related encodings: U+212B, the precomposed U+00C5, or an A-plus-combining-ring sequence. Unicode normalization exists so applications do not have to treat those equivalent forms as unrelated text.
Where Å fits in measurement
One angstrom is 10−10 m, or 0.1 nm. Within measurement notation, it is a non-SI length unit that still appears in atomic-scale distances, crystal structures, and wavelengths. The 2026 SI Brochure lists it among historical decimal multiples and submultiples of SI units.
The unit name may appear as angstrom in English technical material or as ångström when the original spelling is retained. The unit symbol is Å; changing the spelling of the name does not create a different unit symbol.
That status should not be confused with the encoding question. Converting 1 Å to 0.1 nm changes the unit expression and numerical scale. Replacing U+212B Å with U+00C5 Å changes only the Unicode representation.
The same Å is also a letter
U+00C5 is a normal alphabetic character used in languages including Swedish and Norwegian. In a personal name or word, Å is simply a letter. In a scientific expression such as 1.54 Å, context gives the same character the role of a unit symbol.
This is normal in technical notation. A letter can take on a conventional unit meaning without becoming a different character. Unicode therefore does not need a special modern glyph just to distinguish “letter Å” from “angstrom Å”.
Older PDFs, scientific archives, OCR output, and character pickers can still produce U+212B. The glyph gives no warning: the legacy code point usually becomes visible only when a string comparison or normalization step exposes it.
When normalization changes Å to Å, the measurement has not changed. Only the Unicode representation has moved to the preferred canonical form.
That makes this pair different from ordinary look-alikes. Unicode is not merely saying that Å and Å resemble each other; it formally connects them through canonical equivalence.
The same legacy pattern appears with Ω vs Ω and K vs K, although the scientific contexts of those units are different.
Converting Å to nm is not normalization
The angstrom and nanometre are often used for quantities on similar scales, so a few conversions are useful: 1 Å = 0.1 nm, 10 Å = 1 nm, and 100 Å = 10 nm. The conversion changes the numerical value because the units have different sizes.
That is completely separate from replacing Å with Å. Unicode normalization changes only the encoded character; a unit conversion changes the measurement expression. Mixing those two operations in a cleanup script can silently alter scientific data.
Although Å is based on the Latin letter A, the ring is part of the character’s identity. Replacing Å with plain A is not Unicode normalization and can change both language text and measurement notation. A search system may choose accent-insensitive matching for user convenience, but the stored source should not be stripped casually.
Preferred character for new text
Write the angstrom symbol as Å U+00C5 in new text. Preserve Å U+212B only when exact reproduction of a legacy source is part of the job.
For search and comparison, normalized text is the practical choice. If provenance matters, keep the original source alongside it; there is no need to pretend that the legacy code point represents a different length unit.