Blackletter and cursive get grouped together as the fancy ones, which hides the fact that they fail in opposite ways. Blackletter is dense and vertical and falls apart on capitals. Cursive is thin and sloping and falls apart at small sizes. Choosing between them is less about taste than about where the text will be read, and the answer flips depending on whether you are writing a display name or a caption.
Neither style installs a typeface. Both are lookup tables: your letter goes in, a different Unicode character comes out, and that character is what lands on your clipboard.
The blackletter and script alphabets both live in the Mathematical Alphanumeric Symbols block, U+1D400 to U+1D7FF. That block was encoded so mathematicians could distinguish a script capital L from a blackletter capital L in an equation, because in mathematics those are different symbols with different meanings. Decoration was not the point. It is a side effect of a block designed for notation.
That origin explains most of the quirks below. A block built for equations contains exactly the letters equations needed. Where mathematics had no use for a character, the character is not there, and the tool passes your letter through unchanged.
You can see both sets side by side on the fancy text generator, or narrowed to their own families on the old English page and the cursive page.
Blackletter has one specific failure that catches people out, and it is worth knowing before you commit a name to it.
In most blackletter designs the capital I and the capital J are nearly identical. They differ by a small descender or a slight change of curve, at a size where neither is visible. A name beginning with either letter becomes a guess for the reader.
The script alphabet has a milder version of the same issue between capital I and capital T, and a worse one between capital F and capital T in some renderings, because the fonts that draw these code points vary and you do not control which one a reader has.
If your name starts with one of those letters, test it specifically rather than testing a generic sample. Type your own name into the preview, not the word that was already in the box.
Blackletter is dense. The strokes are thick and close together, which means it survives being shrunk better than script does, but it turns into a solid block when the letters are packed. It reads well in short runs of three or four words and poorly in a full sentence.
Script is the opposite. The strokes are thin and the letters lean, so a long phrase still reads as a phrase rather than a wall. But thin strokes are the first thing to disappear when a renderer scales text down or applies anti-aliasing badly, and at profile-name size a script alphabet can fade into the background.
So: blackletter for a short display name, script for a longer line in a bio or a caption. Reverse that and both will disappoint you.
The Mathematical Alphanumeric Symbols block includes several sets of styled digits, but not one for every alphabet. There are bold digits, sans-serif digits, monospace digits and double-struck digits. There is no script digit set and no blackletter digit set.
When a style has no digit of its own, the tool passes your digit through as an ordinary one. A blackletter name containing a number renders as blackletter letters with plain digits sitting among them, which looks like a mistake even though it is the only thing that can happen.
The same applies to punctuation. Neither alphabet includes styled punctuation, so apostrophes, periods and hyphens stay plain throughout.
If your text has digits in it and the mixture bothers you, pick a style that does have matching digits. Bold and monospace both do, and both are on the bold text page and the fancy text generator.
A handful of letters in these alphabets were already encoded elsewhere in Unicode before the mathematical block existed, so they were not encoded a second time. The block has holes at those positions, and the standard points to the older characters instead.
The practical result is that a few letters in the script and blackletter sets come from a different part of Unicode than their neighbours. They are the correct characters and they render correctly in most fonts, but they can be drawn by a different font than the rest of the word, which produces a visible mismatch in weight or slope on some systems.
This is not something you can fix. It is a property of how the standard grew. It is worth knowing because it explains an otherwise baffling effect: one letter in your name looking wrong while every other letter looks right.
A substituted alphabet is a one-for-one exchange. Twenty letters in, twenty characters out. Neither blackletter nor script adds anything to your character count.
What they do add is storage. Both sit above U+FFFF, so each styled letter is stored as a surrogate pair, two units where a plain letter takes one. A field that counts storage rather than characters charges you double, which turns a 30-character display name into a 15-letter one.
This is the same for both styles, so it is not a tiebreaker between them. It is a reason to check the counter before you commit either. The character counter reports characters and storage units separately so you can see which number is close to the limit.
Frames are what add characters, and those are separate from the alphabet. Choosing blackletter and choosing a frame are two independent decisions.
Neither style is good news for assistive technology, and the failure mode is the same for both.
A screen reader meeting U+1D4D0 finds a character named MATHEMATICAL BOLD SCRIPT CAPITAL A. Depending on the reader and its speech dictionary it may announce that full name, spell the run out one character at a time, or skip it entirely and say nothing at all. A name written in script can arrive as silence.
There is no version of this that is fine. If the text is something a person needs in order to reach you, understand you or act on your post, it should be plain. Style a tagline, a divider, a decorative line in a bio, and leave your name, your business and your instructions in ordinary letters.
That is a real cost rather than a technicality, and it applies equally to both alphabets.
Three questions settle it.
How long is the text? Under four words, blackletter is the stronger look and survives the small sizes a name is rendered at. Longer than that, script keeps its shape while blackletter congeals.
Does it start with I or J? If yes, blackletter is out unless you are willing to be misread. Test your own first letter rather than the sample.
Does it contain digits? If yes, both will mix styled letters with plain numbers. Either accept that or move to bold or monospace, which have matching digit sets.
After that it is preference, and preference is a reasonable basis for a decision that only affects how a tagline looks. The cursive page and the old English page each narrow the list to one family so you can compare within a style rather than scrolling past three hundred rows.
Both alphabets depend on the reader's device having a font that covers the code points, and coverage is not universal.
Older Android builds, locked-down work machines, smart TVs and embedded browsers are the usual failures. On those, a character with no available glyph draws as a hollow rectangle, the font's .notdef glyph, sometimes with hex digits inside.
Blackletter and script are both long-standing parts of the standard and are covered better than the newer decorative ranges, but neither is as safe as bold or monospace, which almost every font family includes in some form.
There is no way to test every device. A reasonable proxy is an older Android phone and a plain terminal. If your text survives both, it will survive nearly anywhere, and if it does not, you have learned that before your profile went out to people who will not tell you it looked broken.
The names are used interchangeably for these alphabets. In Unicode the formal name for the letters is fraktur, and old English is the name most people search for.
A few letters were already encoded elsewhere in Unicode before the mathematical block existed, so the standard points to the older characters. Those can be drawn by a different font than their neighbours.
No. Username and handle fields generally permit ASCII letters, digits and a separator only, so a substituted alphabet is refused rather than shortened.