How to Add a Subscript in Microsoft Word

Subscript text sits slightly below the normal line of text and appears smaller than the surrounding characters. You'll see it in chemical formulas like H₂O, mathematical expressions, footnote-style references, and scientific notation. Microsoft Word supports subscript formatting through several methods — and which one works best depends on how you work, how often you need it, and which version of Word you're running.

What Subscript Actually Does (and When You Need It)

When you apply subscript formatting, Word reduces the selected text to roughly 58–65% of the normal font size and drops it below the text baseline. The line spacing around it typically stays consistent, so your document layout doesn't break.

Common use cases include:

• Chemical formulas — CO₂, H₂SO₄, C₆H₁₂O₆
• Mathematical notation — variable subscripts like x₁, x₂
• Trademark and footnote symbols when superscript isn't appropriate
• Technical documentation referencing indexed values

Subscript is different from superscript, which raises text above the baseline (used for exponents like x², ordinal indicators like 1st, or citation numbers). Word treats them as separate formatting options, though they sit right next to each other in the interface.

Method 1: The Keyboard Shortcut ⌨️

The fastest way to apply subscript in Word on Windows is the keyboard shortcut:

Ctrl + =

Here's how it works:

1. Select the text you want to format as subscript
2. Press Ctrl + =
3. The selected text drops below the baseline

To turn subscript off, select the formatted text and press Ctrl + = again. It toggles on and off.

On Mac, the equivalent shortcut is Command + = in most versions of Word for Mac — though some macOS versions and keyboard configurations may require Command + Shift + = depending on your system settings and Word version.

If you're typing on the go and don't want to reach for the mouse, this method is by far the most efficient.

Method 2: The Home Tab Ribbon

If you prefer visual navigation or don't want to memorize shortcuts:

1. Select the text you want to subscript
2. Go to the Home tab on the ribbon
3. In the Font group, click the subscript button — it looks like an X₂ icon
4. Your selected text will drop below the line

Clicking the same button again removes the formatting. This method works identically in Word 2016, 2019, 2021, and Microsoft 365 on both Windows and Mac.

Method 3: The Font Dialog Box

For more control over character formatting at once, use the Font dialog:

1. Select your text
2. Press Ctrl + D (Windows) or Command + D (Mac) to open the Font dialog
3. Under Effects, check the Subscript box
4. Click OK

This method is useful when you're already in the Font dialog adjusting size, style, or spacing — you can apply subscript as part of a broader formatting change without additional steps.

Method 4: AutoCorrect and AutoFormat (For Repeated Use)

If you're working in a document that requires frequent subscript formatting — like a chemistry paper or a lab report — manually applying formatting every time becomes tedious. Word's AutoCorrect feature can be configured to automatically replace specific text strings with pre-formatted characters.

For example, you could set "H2O" to automatically convert to "H₂O" using AutoCorrect. This works best when you have predictable, recurring text patterns.

Alternatively, Unicode character input is worth knowing: many subscript numerals (₀ through ₉) exist as actual Unicode characters. If your document will be copied into environments that don't preserve Word formatting — like emails or plain-text fields — using actual Unicode subscript characters can preserve the visual appearance where Word formatting would not.

Variables That Affect Your Experience 🔧

The same steps produce slightly different results depending on your setup:

When Subscript Formatting Doesn't Carry Over

One thing that surprises many users: Word subscript formatting is document-specific. If you copy subscripted text and paste it into a plain-text editor, a web form, or certain email clients, the formatting disappears and the character appears at normal size on the baseline.

If portability matters, using actual Unicode subscript characters (which can be inserted via Insert > Symbol or pasted directly) is more reliable across environments. However, Unicode subscript coverage is limited — full subscript letters exist for some characters but not all.

For PDFs exported from Word, subscript formatting generally carries through correctly because the PDF renders from Word's formatting instructions directly.

How Subscript Interacts With Line Spacing

One formatting detail worth knowing: in documents with fixed line spacing (set to an exact point value rather than "Multiple" or "At Least"), subscript characters can sometimes get clipped at the bottom. If your subscript looks cut off, checking your paragraph's line spacing settings — rather than the font or subscript formatting itself — is usually where the fix lives.

The relationship between how you work, what version of Word you're running, how your document will ultimately be used, and how often you need subscript formatting all shape which approach actually fits your workflow.