What size should a logo be in an email signature?

120–200px wide is the standard range for horizontal logos (wordmarks). Icon-only or square logos should be 40–60px. Maximum height 60px keeps the logo proportionate to the surrounding text. Use PNG format with a transparent background.

Why does my logo appear too large in Outlook?

Outlook scales images based on display DPI. At 125% or 150% Windows scaling, a 160px logo renders at 200–240px. Fix: add both a width HTML attribute (width='160') and an inline CSS style (style='width:160px;max-width:160px;') to the img tag. Outlook respects the HTML attribute for DPI scaling; the CSS max-width prevents overflow in Gmail.

Should I use PNG or SVG for a logo in an email signature?

PNG. SVG is not supported in desktop Outlook (any version) or many mobile email clients — it renders as a broken image. Export your logo as a PNG at 2x the display size for retina sharpness, then constrain it to the display size with the width attribute.

Email Signature Logo Size

Logo sizing in email signatures has two separate problems: choosing the right display dimensions so the logo doesn't dominate or shrink, and applying the Outlook DPI fix so it doesn't scale unpredictably on high-resolution Windows displays. Both are required.

Updated: March 2026·~3 min read

Quick Reference

Horizontal wordmark:120–200px wide, max 50px tall

Square / icon mark:40–60px × 40–60px

File format:PNG with transparent background

File size:Under 20KB (compress with TinyPNG)

Export size (retina):2× display size, constrain with width attr

Logo Size by Type

Horizontal wordmark (text + icon)

160–200px wide, 35–50px tall

The most common logo format. At 160px, it sits proportionately next to a 14px contact block. Going wider than 200px risks overflowing on mobile email views (320px viewport minus padding).

Icon only / emblem

40–60px square

Small square or circular logos used alone. At 40px they're clear enough to recognize. Going below 32px makes them unreadable on non-retina displays. Often placed to the left of the name.

Stacked logo (icon above text)

80–120px wide, 60–80px tall

Stacked formats run tall. Keep total height under 80px or the logo occupies too much vertical space in a preview pane. Consider using the horizontal version for email signatures instead.

Full-width banner logo

540px wide, auto height

Used when the logo serves as a design header across the full signature. Must stay within 540px (600px - 60px padding margin). This style works better for marketing emails than professional signatures.

The Outlook DPI Scaling Fix

Outlook scales images based on Windows display DPI settings. At 125% scaling (common on 1080p laptops), a 160px logo renders at 200px. At 150% (common on 4K screens), it renders at 240px. The only reliable fix is specifying width in both the HTML attribute and inline CSS:

Correct — both HTML attribute and CSS style:

width="160" — HTML attribute. Outlook reads this to override DPI scaling. Required.

height="42" — HTML attribute. Prevents layout shift while image loads. Recommended.

style="width:160px;max-width:160px;" — CSS. Prevents overflow in Gmail and constrains the image in browser-based clients.

display:block; — Removes the default inline-block gap that appears below images in some email clients (a 4px phantom space).

Retina-Sharp Logos

Export your logo PNG at 2× the display width. Constrain it to the display width using the width attribute. The image renders at double pixel density on retina displays while appearing the correct size everywhere.

Example: display at 160px, export at 320px

→ Export logo-320.png at 320px wide from your design tool
→ Compress with TinyPNG (target under 20KB)
→ Host at your public HTTPS URL
→ Set width="160" and style="width:160px" in the img tag
→ On standard displays: renders at 160px. On retina: renders at 160px but with 320px of pixel data = crisp

Note: The 2× file is larger. If your logo PNG is already under 20KB at 2×, use this approach. If the 2× PNG exceeds 40KB, compress harder or use 1.5× instead.

Format: Why PNG, Not SVG

PNG — use this

Lossless compression. Supports transparency. Renders in all email clients including all Outlook versions, Apple Mail, Gmail, and mobile apps. This is the only safe format for logos in email signatures.

SVG — do not use

Desktop Outlook (2016, 2019, 2021, 365) does not render SVG — it shows a broken image placeholder. Many mobile email clients also block SVG. Even though Gmail and OWA support SVG, you cannot use it if any recipients use desktop Outlook.

JPG — not ideal for logos

JPG uses lossy compression that introduces visible artifacts on sharp edges, solid colors, and text. Logos with text look noticeably blurry as JPG. Only use JPG for photographic images (headshots).

Related Guides

Add Your Logo to a Signature

SignForge applies the Outlook DPI fix to every logo automatically — width attribute and inline CSS, no manual edits needed.

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Works with Gmail, Outlook, Apple Mail & more