Email Size Calculator
Enter the total size of your attachments, the body size and your email provider's limit. The calculator adds the encoding overhead, tells you if the email fits and gives the largest attachment you can send.
- Sent email size
- Attachment limit
- Fits or not
Both the sender's and the receiver's limits apply.
Attachments grow by about a third when they are sent. Email sends files as Base64 text with line breaks, adding about 37%. A 20 MB file becomes about 27.4 MB, which is too big for a 25 MB limit. The largest attachment that fits 25 MB is about 18 MB.
Email size chart
Encoding adds about 37%. Search for a size.
| Attachment (MB) | Sent (MB) | Fits 25 MB | Fits 10 MB |
|---|---|---|---|
| 1 | 1.4 | Yes | Yes |
| 5 | 6.9 | Yes | Yes |
| 7 | 9.6 | Yes | Yes |
| 10 | 13.7 | Yes | No |
| 15 | 20.6 | Yes | No |
| 18 | 24.7 | Yes | No |
| 20 | 27.4 | No | No |
| 25 | 34.3 | No | No |
25 MB limit.
Attachment and limit
25 MB limit. Slide the attachment size.
The bar fills towards the limit as the attachment grows.
How to check email size
File to sent size. Step through it.
Add files
Total MB.
Zip several files together. It saves a little space and sends as one attachment.
Attach, compress or share a link
Ways to send. Compare them.
Simple.
Smaller.
No limit.
Cloud links also let you update a file after sending.
Before sending
Email checks. Tick each item.
Tick each item as you go.
Photos and videos are already compressed, so zipping them barely helps.
What you get
Email sizing. Each tile explains one result.
MB.
Yours.
Or not.
Attachment.
Encoding.
Many work email servers reject messages over 10 MB, even if your provider allows more.
Frequently Asked Questions
No question matches that search.
Why is my email bigger than the attachment?
Attachments are encoded as Base64 text, which adds about thirty-seven per cent.
What is the largest attachment for a twenty-five megabyte limit?
About eighteen megabytes.
Does the receiver's limit matter?
Yes. The email must fit both your limit and theirs.
How can I send a large file by email?
Share a cloud storage link instead of attaching it.
Does zipping files make them smaller?
For documents, often. Photos and videos barely shrink.
What is the Gmail attachment limit?
Twenty-five megabytes, counting the encoded size.
Do multiple attachments add up?
Yes. The limit is for the whole email.
Send it first time
Check the real size before you press send, and switch to a link when the files are too big.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.