How to Add Custom Fonts to Klaviyo

Your email template is live. The layout looks sharp. But then you open it on desktop — and the font is wrong.

Instead of your sleek brand typeface, you’re staring at Arial. Or Times New Roman. Generic. Forgettable.

This happens to almost every marketer who skips font customization in Klaviyo. And it costs you more than aesthetics — emails with consistent branding generate 33% higher revenue than those without.

Custom fonts change that. They make your emails feel intentional, on-brand, and professional — from the subject line all the way to the footer.

This guide shows you exactly how to add custom fonts to Klaviyo, which methods actually work, and what to watch out for so your emails render correctly across every inbox.

Why Custom Fonts Matter in Email Marketing

Before diving into the steps, understand what’s at stake.

Typography is one of the first things readers notice. Research shows that 95% of design is typography, and brands that maintain consistent typography see up to 23% higher brand recognition compared to inconsistent ones.

In email marketing specifically:

• Personalized, well-designed emails deliver 6x higher transaction rates than generic ones (Experian)
• Emails with strong visual hierarchy get 80% more readability engagement because readers can scan and find what they need faster
• 47% of email recipients decide to open an email based on the subject line alone — but typography keeps them reading once they’re in
• Mobile accounts for 41.6% of all email opens (Litmus, 2024), which means fonts that don’t render well on smaller screens kill conversions fast
• Poor email design is cited as the top reason 69% of subscribers unsubscribe from brand emails

The bottom line: if your emails look off, people leave. Custom fonts fix the “looks off” problem at the source.

Understanding How Email Fonts Work

Here’s what most guides skip: not all email clients support custom fonts.

Email clients fall into two camps:

Supports web fonts:

• Apple Mail
• iOS Mail
• Outlook for Mac
• Samsung Mail
• Thunderbird

Does NOT support web fonts:

• Gmail (most versions)
• Outlook 2013–2019 (Windows)
• Yahoo Mail

This matters because roughly 58% of all email opens happen in clients that don’t fully support custom fonts (Litmus Client Share, 2024). That’s why fallback fonts exist — and why setting them correctly is non-negotiable.

Your strategy should be: serve the custom font where supported, fall back gracefully where it isn’t.

Method 1 — Using Klaviyo’s Built-in Font Selector

The easiest starting point. Klaviyo includes a set of pre-approved web-safe and Google Fonts directly in the drag-and-drop editor.

Step-by-step:

1. Open your Klaviyo account and navigate to Email Templates
2. Open an existing template or create a new one
3. Click on any text block inside the editor
4. In the right-hand panel, locate the Font Family dropdown
5. Browse the available font options — Klaviyo includes Google Fonts like Lato, Montserrat, Roboto, and Open Sans alongside web-safe options
6. Select your desired font
7. Set the font size, weight, and line height to match your brand
8. Click Save

What you get: Clean, simple font selection with no code required. These fonts load via Google’s CDN and render well in supported email clients.

Limitation: You’re limited to Klaviyo’s built-in font library. If your brand uses a proprietary typeface or a font not in their catalog, you need Method 2 or 3.

Method 2 — Adding Google Fonts via Custom HTML

If you want access to the full Google Fonts library — over 1,500 free typefaces — you can embed them directly into your email template using a custom HTML block.

Step-by-step:

1. Go to fonts.google.com and find your font
2. Click Select this style for the weight(s) you need (regular, bold, italic)
3. In the panel on the right, copy the <link> embed code — it looks like:

<link href=”https://fonts.googleapis.com/css2?family=Playfair+Display:wght@400;700&display=swap” rel=”stylesheet”>

1. In Klaviyo, open your template editor
2. Click the Source or HTML view button (looks like < > in the editor toolbar)
3. Paste the Google Fonts <link> tag inside the <head> section of your template HTML
4. In your text blocks, update the CSS font-family to reference your new font with a fallback stack:

font-family: ‘Playfair Display’, Georgia, serif;

1. Save and preview across multiple email clients using Klaviyo’s preview tools

Pro tip: Always test in Klaviyo’s Preview & Test section before sending. Send yourself a test to both a Gmail and an Apple Mail address to see exactly how the font renders in each.

Method 3 — Using @font-face for Fully Custom or Proprietary Fonts

This is the method for teams with branded typefaces that aren’t on Google Fonts — think custom-licensed fonts, agency-designed typefaces, or fonts purchased from Fonts.com or MyFonts.

What you need first:

• Your font files hosted on a publicly accessible URL (your website, CDN, or AWS S3 bucket)
• The font in .woff and .woff2 formats for best compatibility
• The font’s licensing must permit embedding in emails (check your license)

Step-by-step:

1. Upload your font files to your website or hosting server — for example: https://yourdomain.com/fonts/yourbrandfont.woff2
   
   
2. Open your Klaviyo template in HTML/Source view
   
   
3. Add the @font-face declaration inside the <style> block in your template’s <head>:
   
   

<style>

  @font-face {

    font-family: ‘YourBrandFont’;

    src: url(‘https://yourdomain.com/fonts/yourbrandfont.woff2’) format(‘woff2’),

         url(‘https://yourdomain.com/fonts/yourbrandfont.woff’) format(‘woff’);

    font-weight: normal;

    font-style: normal;

  }

</style>

1. Apply it to your text elements using inline CSS or a style block:

font-family: ‘YourBrandFont’, Helvetica, Arial, sans-serif;

1. Test across email clients — Apple Mail, iOS Mail, and Outlook for Mac will render the custom font; Gmail will fall back to Helvetica or Arial

Why the fallback stack matters: Gmail alone accounts for 27.8% of all email client usage globally (Litmus, 2024). Without a fallback, Gmail users see the browser’s default font — which is rarely what you want.

Method 4 — Setting Global Font Styles in Klaviyo Templates

If you’re managing multiple email templates, setting fonts one block at a time is slow. Use Klaviyo’s template-level styling to apply fonts globally.

Step-by-step:

1. Open your template in the drag-and-drop editor
2. Click on the canvas background (outside any content block) to open Email settings in the right panel
3. Under Typography, set your default font for body text and headings
4. Any new text block added to the template will automatically inherit these settings
5. To override individual blocks, simply click that block and change font settings in its panel

This approach saves significant time when building new campaigns and ensures consistency across your entire email — brands that enforce design consistency in email see 20% higher click-through rates compared to those with inconsistent styling.

How to Set Font Fallbacks Correctly

Your fallback stack is your safety net. Here’s how to build one that actually works:

General fallback logic:

/* Sans-serif custom font */

font-family: ‘YourFont’, Arial, Helvetica, sans-serif;

/* Serif custom font */

font-family: ‘YourFont’, Georgia, ‘Times New Roman’, serif;

/* Monospace custom font */

font-family: ‘YourFont’, ‘Courier New’, Courier, monospace;

Rules to follow:

• Always end with a generic family (sans-serif, serif, monospace) as the final fallback
• Choose web-safe fonts (Arial, Georgia, Verdana) as your first fallback — they’re available on virtually every device
• Keep your stack to 3–4 fonts maximum; more than that is unnecessary
• Match the character of your custom font — if it’s a geometric sans-serif, don’t fall back to a serif

Testing Custom Fonts Before You Send

This step is where most marketers cut corners — and regret it.

Testing checklist:

• Klaviyo’s built-in preview — use the Preview & Test function to check desktop and mobile views
• Send test emails to accounts on Gmail, Apple Mail, and Outlook to see real rendering
• Email on Acid or Litmus — these tools simulate 90+ email clients and show you exactly how fonts render in each one; brands using inbox testing tools reduce email rendering issues by 73% (Email on Acid, 2023)
• Check load time — custom fonts add HTTP requests; if your email takes longer than 3 seconds to load, you risk a 53% drop in mobile engagement
• Dark mode preview — test how your font colors appear in dark mode, since over 35% of users now read emails in dark mode (Litmus, 2024)

Common Mistakes When Adding Custom Fonts to Klaviyo

Forgetting to set fallback fonts. If your primary font doesn’t load in Gmail, no fallback means readers see a random system font. Always define your stack.

Using fonts without proper hosting. If your .woff2 file is hosted on a local server or behind authentication, email clients can’t access it. The URL must be publicly accessible at all times.

Overloading your font import. Importing all 9 weights of a font when you only use 2 adds unnecessary load time. Import only the weights and styles you actually use — this alone can cut font load time by 60–70%.

Not testing on Outlook Windows. Outlook 2013–2019 on Windows uses Microsoft Word’s rendering engine, which ignores most CSS including custom fonts. These versions still account for around 9% of business email opens. Always have a clean fallback.

Mixing too many typefaces. Stick to 2 fonts maximum per email — one for headings, one for body. Using 3 or more fonts in a single email reduces perceived professionalism by 38% in design studies.

Ignoring line-height and letter-spacing. Custom fonts often need adjusted spacing compared to system fonts. A line-height of 1.5–1.6 for body copy and 1.2–1.3 for headings is a reliable starting point.

Best Practices for Email Typography in Klaviyo

• Minimum body font size: 14px — anything smaller becomes hard to read on mobile, where 61% of emails are now opened (HubSpot, 2024)
• Heading font size: 22px–28px for strong visual hierarchy
• Maximum line length: 600px — Klaviyo’s default template width is optimized for this; going wider reduces readability on mobile
• Contrast ratio: 4.5:1 minimum between text and background — required for accessibility and improves readability for all readers
• Bold for emphasis, not color — color emphasis can disappear in dark mode or on low-contrast displays
• Left-align body copy — centered text beyond 2–3 lines is harder to read and reduces comprehension speed by up to 25%

Conclusion

Adding custom fonts to Klaviyo isn’t complicated — but doing it right requires more than just dropping a font name into a text box.

You need the right method for your font type (built-in, Google Fonts, or @font-face), a solid fallback stack, and thorough testing across email clients before anything goes to your list.

Here’s a quick recap of what to do:

• Start with Klaviyo’s built-in font selector for common Google Fonts
• Use the HTML <link> method for any font on Google Fonts not in Klaviyo’s default list
• Use @font-face for proprietary or licensed brand fonts hosted on your server
• Set a web-safe fallback for Gmail and Outlook Windows users (9–28% of your list, depending on your audience)
• Test in at least 3 email clients before sending
• Apply global fonts in Klaviyo’s template settings to save time across campaigns

Typography is one of the highest-leverage, lowest-effort improvements you can make to your email program. One afternoon of setup saves every future campaign from looking like it was designed in 2009.

Get your fonts right — then focus on what those emails are supposed to do: book meetings, drive revenue, and build a brand worth remembering.