Does my image actually stay on my device?

Yes. The resize runs in your browser using the Canvas API. We never see, store, or transmit your image. You can verify this in your browser's network tab — only static files load, no upload requests.

What's the catch? Why is this free?

No catch. The whole tool runs in your browser, so there are no servers and no bandwidth costs. We're validating demand first; a paid tier with batch resize and API access may come later.

Can I batch resize multiple images?

Yes — one click exports your photo resized to all 17 marketplace presets as a ZIP. Single-image batch export is built in; multi-image upload is on the roadmap.

Do you support my country's platform?

Yes — imgsize.cc supports Amazon (US, IN), Etsy, Shopify, Walmart, Flipkart, Instagram, TikTok, YouTube, LinkedIn, X, Facebook, Pinterest, Threads, Mastodon, Twitch, Snapchat, Behance, Substack, Medium, Dribbble, Tumblr, Vimeo, SoundCloud, Discord, WhatsApp and Spotify. If we don't have your platform yet, request it via email.

What image formats can I export?

JPEG, PNG, TIFF, and GIF. PNG is the default for product photos because it preserves transparency and is the format Amazon prefers. JPEG is smaller and great for social posts.

Substack Post Banner Size: 1456×180 (2026 Spec)

Substack publication banner size: the 2026 spec

This guide covers the official spec, format requirements, and the practical workflow imgsize.cc uses to get it right in your browser.

Why these dimensions

Substack publication banners appear at the top of every post. The 1456×180 pixel spec (8:1 ratio) renders sharp on retina displays. Use a brand-aligned graphic or photo.

Specification breakdown

Size: 1456×180 px (mandatory)
Format: JPEG, PNG
Max file size: 10 MB
Aspect ratio: 8:1 (banner)

The "safe area" inside the frame

Crop the central content of your image to the central 80% of the frame. Substack Post Banner may crop or overlay UI elements near the edges, so critical content should stay well within the safe zone.

Common mistakes

Text in the center — covered by publication name overlay
Off-brand colors — looks inconsistent
Aspect ratio off — letterboxed with white

Frequently asked questions

Does the banner show on the email?

Yes, on both the web archive and email version of every post.

How imgsize.cc handles it

Drop your source image into the workbench above. The crop box defaults to an 8:1 aspect ratio matching Substack's banner spec. Resize, crop, and download as a 1456×180 pixel PNG — all in your browser, no upload required.

Substack Post Banner

Spec details