Outline text generator

The outline style has a proper name: double-struck, or blackboard bold. Bold letters are awkward to write in chalk, so mathematicians draw one stroke of a letter twice, and printed maths took up the same look. It marks the main sets of numbers: ℕ for the natural numbers, ℤ for the integers (from the German Zahlen, numbers), ℚ for the rationals (from quotient), ℝ for the real numbers and ℂ for the complex numbers.

Unicode added a full double-struck alphabet in 2001, with capitals, small letters and the digits 𝟘 to 𝟡, in the Mathematical Alphanumeric Symbols block. That's the set this generator draws on, with seven exceptions.

Those seven capitals, the letters most used for number sets, were in Unicode years before the rest of the alphabet. They live in the Letterlike Symbols block, beside signs like ℃ and ™. When the full alphabet arrived, Unicode left seven empty slots where they would have gone rather than encode them twice, so a generator has to fill each gap with the older character.

On some devices the older seven are drawn from a different font than their neighbours, so in 𝕆ℙ𝔼ℕ ℍ𝕆𝕌𝕊𝔼 the P, N and H can sit at a slightly different weight or height. Small letters and digits have no gaps, so 𝕠𝕡𝕖𝕟 𝕙𝕠𝕦𝕤𝕖 always comes from a single set.

Tip: If a word is full of C, H, N, P, Q, R or Z, try it in lowercase, or look at it on a second phone before you post.

Outline letters aren't the only hollow option. Circled and boxed letters put a solid letter inside an outlined shape, which behaves differently at small sizes.

Outline keeps each letter's own shape, so it suits names and headings. Bubble letters are rounder and friendlier, and the circle stays visible even when the letter inside gets small. Boxed letters look like keys on a keyboard; since everything becomes a capital and digits stay plain, keep them for a label such as 🄽🄴🅆.

• Use it large or not at all. The hollow comes from a thin gap inside each stroke, and that gap is the first thing to vanish at small sizes.
• Capitals make the effect easiest to see, so 𝕊𝕌𝕄𝕄𝔼ℝ 𝕊𝔸𝕃𝔼 works better as a heading than the lowercase version.
• Outline digits suit years and countdowns: 𝟚𝟘𝟚𝟞, or 𝟛 𝕕𝕒𝕪𝕤 𝕝𝕖𝕗𝕥.
• Keep the sentence around it plain. One outlined word draws the eye; a whole caption in outline is tiring, and screen readers may announce every character as “mathematical double-struck” plus the letter.
• Write hashtags, @mentions, links and anything people need to copy in plain characters.

If you want letters with a coloured outline on a photo, a poster or a Story graphic, that's a design effect, not a character. Design apps such as Canva have outline and hollow text effects you can apply to any font, and the result is saved into the image. The characters on this page are for text boxes: bios, captions, comments and chats.