Check Your HTML Email Size Before Sending
Paste your HTML email and see its exact size, breakdown, structure, images, links and CSS — with practical recommendations to make it more efficient.
What Is an Email Size Checker?
An email size checker measures the exact size of your HTML email and breaks it down so you can see what is making it large. It counts the true UTF-8 byte size, then analyzes the structure, inline CSS, text, embedded image data, URLs, images and links. You get a transparent picture of your template's technical footprint — and clear steps to make it leaner.
Why Does Email Size Matter?
Large emails load slowly, especially on mobile connections. Bloated markup increases the chance of rendering issues, and some clients clip or truncate very large messages. Keeping your HTML reasonably compact is one of the cheapest performance wins in email marketing.
How Large Should an HTML Email Be?
There is no single universal limit. Email providers and clients have different clipping, processing and message-size behavior that can change over time. The tool provides MailCannon size guidance as practical advice, not a specification:
- Under 50 KBLow — a compact template that loads quickly.
- 50–100 KBModerate — worth a quick review of images and CSS.
- 100–150 KBLarge — look for embedded images and duplicated styles.
- 150 KB+Very Large — likely to be slow and at higher risk of clipping.
Why Email Size Matters
How to Reduce HTML Email Size
- Remove unnecessary markup. Fewer nested tables, no stray divs, no unused blocks.
- Reduce duplicated inline CSS. Repeated styles inflate the source quickly — reuse compact email-safe structures.
- Avoid large embedded images. Host images over HTTPS instead of embedding base64 data.
- Remove unnecessary comments. Large comments add bytes without visible content.
- Keep templates simple. Fewer elements, links and duplicated blocks means a smaller payload.
Does Image Size Count Toward HTML Email Size?
It depends on how the image is included:
- HTML source size — the raw bytes of your HTML file, measured exactly by this tool.
- Externally hosted image size — loaded separately from the HTML and NOT included in the HTML size.
- Embedded image / data URI size — inlined in the HTML and fully counted, since it is part of the source.
Frequently asked questions
Accuracy & Privacy
Every measurement comes from the actual HTML you paste. The source size is its real UTF-8 byte length; image, link and element counts are real counts from your markup; embedded data URI sizes are calculated from the source; external image file sizes are never invented or downloaded. The entire analysis runs in your browser, so your HTML is never uploaded or stored.