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CSS Properties

line-height

CSS property · 19 supported, 2 partial, 0 unsupported across 21 clients

line-height is safe in 19 of 21 email clients as of Sep 2, 2026, the holdouts are Outlook (New), Outlook Classic.

  • 7/7 webmail, 4/6 desktop, 8/8 mobile clients support line-height fully.
  • Partial in Outlook (New), Outlook Classic, behavior differs from browsers, test before relying on it.
  • Outlook Classic (Word engine, supported to at least 2029) does not fully support line-height, and its replacement changes little here; see the deprecation diff.
  • Across all clients, only 6 of 298 tracked HTML/CSS features render identically everywhere.

Source: caniemail.com (MIT), via the Emailens engine. Last tested upstream Oct 2, 2021, synced by Emailens Sep 2, 2026.

line-height controls the vertical rhythm of text and is one of the most legibility-critical CSS properties in email. Email clients tend to add their own baseline corrections, and Outlook on Windows often shifts line-height calculations by 1–2 pixels relative to web browsers, which can cumulatively offset long blocks of body copy.

Client Support

ClientCategoryEngineSupport
GmailwebmailGmail WebSupported
Gmail AndroidmobileGmail MobileSupported
Gmail iOSmobileGmail MobileSupported
Outlook 365webmailOutlook WebSupported
Outlook (New)desktopOutlook WebPartialSee caveat 1
Outlook ClassicdesktopMicrosoft WordPartialSee caveat 1
Outlook iOSmobileOutlook MobileSupported
Outlook AndroidmobileOutlook MobileSupported
Outlook for MacdesktopWebKitSupported
Apple MaildesktopWebKitSupported
Apple Mail iOSmobileWebKitSupported
Yahoo MailwebmailYahooSupported
Yahoo Mail AndroidmobileYahooSupported
Yahoo Mail iOSmobileYahooSupported
Samsung MailmobileSamsungSupported
ThunderbirddesktopGeckoSupported
HEY MailwebmailWebKitSupported
Proton MailwebmailProtonSupported
AOL MailwebmailAOLSupported
FastmailwebmailFastmailSupported
SuperhumandesktopBlinkSupported

Documented caveats (1)

  1. 1.Outlook (New), Outlook Classic: Buggy. em and px units behave weirdly. Use mso-line-height-rule:exactly.

Caveats recorded by caniemail.com (MIT) and carried verbatim, one entry per wording rather than per client.

Client-by-client behaviour for line-height

Fully supports line-height (19): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, AOL Mail, Fastmail, Superhuman.

Partial support (2): Outlook (New), Outlook Classic. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

When to use line-height in email

  • Setting comfortable body-copy leading (typically 1.4–1.6) for readability on small screens.
  • Tightening headline leading to keep multi-line titles visually unified.
  • Acting as a vertical-spacer trick by setting a large line-height on an empty table cell.

Rendering behaviour and edge cases

  • Outlook on Windows uses a different baseline algorithm and can shift text vertically by a pixel or two compared to web browsers.
  • Some Android clients scale line-height with user accessibility text-size settings, breaking precise vertical rhythm.
  • Setting line-height as a unitless number (e.g. 1.5) is more reliable than fixed px values, as it scales with the inherited font-size.

Recommended fallback strategy

Always pair font-size with an explicit line-height. Prefer unitless values for inherited typography. For pixel-perfect spacer rows, combine an explicit line-height with a height attribute on the <td> to give Outlook a stable vertical baseline.

Fixes & Workarounds

Outlook (New)

Partial

"line-height" is not supported in this email client.

Outlook Classic

Partial

"line-height" is not supported in this email client.

Related Features

!important accent-color align-items animation aspect-ratio backdrop-filter background background-blend-mode

Check your own HTML for line-height

Paste your own, or run the sample below. Analyzed in this page, with no signup and nothing stored.
Zero-Friction Engine Preview

Test your line-height layout across 21 email clients

Preview rendering, catch CSS issues, and see how line-height displays across Outlook, Gmail, and Apple Mail. Free, no account needed.

Instant live preview · No signup required · 21 email engines

Last tested upstream: · Last synced by Emailens:

caniemail.com (MIT) records Oct 2, 2021 as the last time line-height was tested in a real client, 4 years before this sync. Syncing copies that result forward, it does not re-test it. Carried in @emailens/engine data v0.12.2.