Email File Size Checker

Email File Size Checker measures the size of your email HTML and gives a clear loading-speed warning before you send. Paste your exported campaign code or select an HTML file to see its size in bytes and kilobytes, whether it is approaching Gmail’s clipping threshold, and which practical improvements can keep the message lean.

Large marketing emails can load slowly on mobile networks and may be clipped by Gmail, leaving subscribers to click “View entire message” before they can see all of your content. This free browser-based checker helps email marketers, developers, and designers catch that risk during QA. Your content stays in your browser and is never uploaded.

• Instant HTML size analysis: Measure pasted email source or a local HTML file in bytes and KB.
• Gmail clipping warning: See whether your message is safely below, nearing, or over the commonly cited 102 KB Gmail HTML threshold.
• Loading-speed guidance: Get a plain-language assessment based on email HTML weight.
• Code composition details: Review character count, line count, image tags, links, comments, base64 images, and style blocks.
• Actionable optimization tips: Recommendations adapt to the issues found in your source.
• Private local analysis: The checker runs entirely in your browser with no upload or account required.

1. Export the final email HTML from your email service provider, builder, or development workflow.
2. Paste the code or choose an HTML file using the input area above.
3. Review the file-size status and Gmail clipping indicator. Keep HTML below 100 KB, with extra room for your sending platform’s additions.
4. Check the composition summary for base64 images, excessive comments, duplicated markup, or unusually large style blocks.
5. Apply the recommendations, export again, and recheck the exact final code before scheduling your campaign.

Example 1: Safe newsletter. A 42 KB exported newsletter contains 14 hosted images and concise HTML. It receives a “Good” loading assessment and is comfortably below the Gmail clipping warning level.

Example 2: At-risk promotional campaign. A 96 KB campaign has several repeated product modules and verbose editor comments. It may still send, but should be simplified before the ESP adds tracking or personalization code.

Example 3: Clipped email risk. A 128 KB email contains a base64-encoded logo and multiple hidden desktop/mobile content blocks. The checker flags a high risk of Gmail clipping and recommends switching to hosted images and removing duplicated markup.

• Protect important content: Reduce the chance Gmail hides your footer, offer details, or tracking pixel behind clipped content.
• Improve mobile experience: Leaner emails are friendlier to recipients on slower connections.
• Catch problems before send: Add a quick technical QA check before a campaign reaches your list.
• Make optimization concrete: Turn a vague “email is too heavy” concern into measurable size, thresholds, and next actions.
• Keep your content private: Analyze drafts locally without uploading customer-facing campaign code.