Optimise Images for Email
Compress and format images correctly for every major email client and marketing platform — without ever uploading the source file.
Email image optimisation is deceptively technical. Every email client caps attachments at a different size (25 MB for Gmail, 20 MB for Outlook, 5 MB for some corporate mail policies), every marketing platform re-encodes at ingest (Mailchimp, Klaviyo, HubSpot all downscale to 600 px render width), and email HTML support for modern formats is inconsistent (Outlook desktop can't render WebP in-body). The right image for your email depends on where it's going.
This hub groups every email-related preset in one place: attachment compression for personal and corporate mail, retina-optimised images for marketing platforms, and small-file presets for transactional and cold-outreach flows. Every preset compresses in your browser — the source image never leaves your device.
For the underlying decisions — quality settings, dimension ceilings, format choice — the two rules of thumb are: (1) target 1200 px at quality 82 for anything embedded in a marketing template (600 px render × 2 for retina), and (2) stay under 5 MB per attachment for anything sent to a corporate address you don't already know.
Email clients (attachment size)
Presets tuned to each major email client's attachment cap. Use these when you're attaching a photo to a message, not embedding in a marketing template.
Email marketing platforms
Presets tuned for Mailchimp, Klaviyo and HubSpot email template rendering. Every major marketing platform renders at 600 px width — supply 1200 px retina JPEG.
Transactional & specialist email
Small-file presets for transactional email, cold outreach and email signatures where deliverability matters more than image weight.
Related tools
Frequently asked questions
- What's the safest attachment size for email in 2026?
- Under 5 MB per attachment is universally safe. Gmail and Yahoo Mail cap at 25 MB, Outlook.com at 20 MB, but many corporate mail systems cap much lower (2–10 MB). If you don't know the recipient's server-side policy, under 5 MB is the safe ceiling.
- Should I use WebP or JPEG for email marketing images?
- JPEG. Outlook desktop still doesn't render WebP in-body, and Outlook has a substantial B2B market share. Send WebP only for platforms where you know 100% of subscribers are on WebP-capable clients (e.g., mobile-only newsletter audiences).
- Do email marketing platforms re-compress uploads?
- Yes. Mailchimp, Klaviyo and HubSpot all downscale uploads to 600 px render width and re-encode with their own quality settings. Uploading a clean 1200 px JPEG (retina at 600 px) at quality 82 lands optimally after their re-encode.
- Does compressing before send actually improve deliverability?
- For cold outreach and transactional email routed through SMTP providers (SendGrid, Postmark, SES, Instantly), yes — heavy attachments trigger spam filters more aggressively than light ones. For warm personal email, less so, but recipients on slow mobile connections still benefit.
- Are my images uploaded anywhere?
- No. Every preset on this site compresses in your browser using the Canvas API. Your source image never leaves your device — only the compressed result you download.