How to choose fonts that distinguish I, l and 1

Some fonts make an uppercase I, a lowercase l and the number 1 look almost identical. That can cause mistakes in passwords, product codes, serial numbers and programming. You can compare the fonts already on your computer and choose one whose characters are easier to tell apart.

The Installed Fonts tool lets you preview your own text in the fonts on your computer. Use a short sample containing all three characters, then check it at the size and weight you will actually use.

Compare the characters in your fonts

1. Open the Installed Fonts tool on a computer in Chrome or Edge. Other browsers may show a reduced version of the tool or may not support it.
2. Use the preview for your own text and enter a sample such as I l 1 | Il1 | ill | 111. The first three characters are uppercase I, lowercase l and the digit one.
3. Look through the font previews and compare the three characters side by side. Pay attention to their tops, bottoms, curves and any small bars or hooks.
4. Repeat the comparison in a longer example from your real use, such as Ill1 or a product code. Similar characters can be harder to spot when they appear among other letters and numbers.
5. Compare promising fonts at the size and weight you need. A shape that looks obvious when large can become unclear in a small label or a light font weight.

Choose a font based on what you see

The uppercase I has bars at the top and bottom

Those bars make uppercase I easier to separate from a plain lowercase l. They are common in serif fonts, but some sans serif fonts also use them. If you like the font overall and its lowercase l is still distinct from the number 1, this can be a clear choice for paragraphs, labels or forms.

The lowercase l has a curve or a foot

A small curve or horizontal foot at the bottom can keep lowercase l from looking like a straight line. Check that the detail remains visible at your intended size. A very subtle foot may disappear in small text, on a low-quality display or in a printout.

The number 1 has an angled top or a base

A slanted top, a small flag or a bottom base can distinguish the digit 1 from both letters. Look at how the character appears next to other numbers as well. If you use the font for account numbers or codes, check a full string rather than judging the digit by itself.

Two or more characters still look alike

Keep comparing. A font may distinguish uppercase I from lowercase l but leave lowercase l and 1 almost identical. For a code or serial number, choose a font that makes all three clear, or add a second check such as grouping the code into short sections. Do not rely on color alone to tell the characters apart.

Pick a font for the task

For code, spreadsheets and fixed-width identifiers, compare monospaced fonts. Each character takes the same horizontal space, which keeps columns and codes aligned. Monospacing does not automatically make I, l and 1 distinct, so inspect the actual shapes before choosing.

If they are available on your computer, you could compare fonts such as Consolas, Menlo, Source Code Pro or Atkinson Hyperlegible. Treat these as candidates, not guarantees: font versions and display sizes can change how a character looks, and the best choice is the one that stays clear in your own sample.

For ordinary reading, a familiar proportional font may be more comfortable. The letters do not all take the same width, but that is not a problem when the text is prose. Use the preview to check that the characters remain identifiable without making every line look widely spaced.

For a printed label or form, choose a font with clear shapes and enough weight to survive printing. For a small screen, avoid very thin strokes. If the text is important, print a sample or view it on the target screen before applying the font everywhere.

Check the font where people will read it

A font preview shows how the font looks on your computer, but it does not guarantee the same font will be available on someone else's device. If you choose a font for a document, website or shared file, check how it will be delivered. A font that is not installed or embedded may be replaced with a different one, changing the shapes you selected.

Also check the final text at its real size, in its real setting. A high-resolution laptop screen, a printed receipt and a dim phone display can make the same character details look different. When a code must be read correctly, include a clear font choice and test the final version before sharing or printing it.