How do I compress an image to under 500KB for Reddit?

Upload the image, select target-file-size mode, type 500 in the field and select KB. The tool binary-searches the quality slider for the highest quality that produces a file ≤ 500KB. If your source image is too high-resolution to hit 500KB even at quality 10, it automatically downscales to 75%, 50%, or 33% of the original dimensions until it fits.

What's the Gmail attachment size limit?

Gmail caps inline attachments at 25MB per file. A modern phone photo can blow that limit. Use target-file-size mode set to 25MB to make sure the compressed result fits.

What's the Discord file size limit?

Discord caps free-tier uploads at 8MB per file (Nitro raises this to 50MB). Set the target to 8MB and the compressor will guarantee the result is under that limit.

Should I compress to JPEG or WebP?

JPEG for universal compatibility (every device, every email client). WebP for the web — typically 25-35% smaller than JPEG at the same visible quality. Don't use PNG to compress photos: PNG is lossless and will produce a much larger file than JPEG/WebP.

Why does my compressed image look the same size?

If you chose PNG output, there's almost no compression — PNG is lossless. Switch to JPEG or WebP to actually reduce the file size. If you chose quality 100, you've asked for no quality loss; drop to 80 (or lower) to see real reductions.

← Poster Poster

Free image compressor · Browser only · No upload

Compress an image in your browser. No upload.

Poster Poster Compress is a free in-browser image compressor for JPG, PNG, and WebP. Adjustable quality, live file-size comparison. No upload, no signup, no watermark.

Drop in an image, pick a format, drag the quality slider, see the new file size, hit download. Everything happens on your device.

1. Choose an image

2. Output format

3. How should we compress?

Quality80

Lower = smaller file, more visible artefacts. 80 is a sensible default for social media; drop to 60-70 for email attachments where size matters more than fine detail.

Often used together

All four tools are free, browser-only, no signup required.

🖼️

Resize for bigger savings

Smaller dimensions = much smaller files. Pair resize + compress for the biggest size cuts.

📄

Combine into one PDF

Merge several compressed images into one PDF — one email attachment instead of five.

🎨

Design from scratch

Need a fresh poster instead of compressing an existing one? Build it in the browser.

When you'd use this

Reddit image posts (under 500KB) — Reddit compresses image previews aggressively, and posts above ~500KB get downsized in feed view. Use the target-size mode to set 500KB and the tool returns the highest quality that fits.
Email attachments (under 25MB) — Gmail and Outlook cap inline attachments at 25MB. A modern phone photo can blow that limit on its own. Set target-size to 25MB.
Discord uploads (under 8MB free / 50MB Nitro) — set the target to 8MB to avoid the "file too large" dialog every time.
UK passport / DVLA photo uploads — government photo upload portals usually cap at 2MB with strict dimensions. Pair /resize for the dimensions, then compress to fit the size limit.
Job application portals — LinkedIn Easy Apply, Indeed, and most ATS forms cap CV / portfolio images at 2-5MB.
Web upload forms — most CMSes and signup forms cap at 2-5MB. Compress without re-shooting.
Faster site loading — over-large images are the #1 cause of slow web pages. Compress before you upload to your CMS or e-commerce site.
Social media drafts — Instagram and Facebook re-encode on their end anyway, but starting from a smaller source saves upload time and avoids visible double-compression artefacts.

JPEG, WebP, or PNG?

JPEG — the safe default. Universal support, good quality at 80, great compression at 60-70. Use for photos.
WebP— usually 25-35% smaller than JPEG at the same visible quality. Supported by every modern browser plus Apple/Android natively. Use when output is for the web and you don't need to email the file.
PNG— lossless. The compress tool will re-encode the file (which strips EXIF / metadata) but won't shrink the actual pixels. Use when you need transparency or a perfect-quality result.

Why does the compression happen in your browser?

Most online compressors upload your image to a server, run the compression there, and hand the result back as a download. That works, but it's slow over a phone connection and the privacy story is murky — your photo lives on someone else's server until they decide to delete it.

This tool runs entirely in your browser via the HTML Canvas API. Your image is read into memory locally, the compression happens on your device, and the result is handed back to you as a download. Nothing leaves your laptop or phone. It works offline once the page has loaded.

Often used together with

The resize tool changes pixel dimensions; this one changes file size. They pair well: resize first to the target platform's dimensions, then compress to fit under any upload limit. The file → PDF tool is the third in the set — combine multiple images into one PDF when an email needs a single attachment.

Compressing every weekly post by hand?

If you're manually compressing the same kind of image every week — gig posters, weekly menus, class timetables — the underlying problem is recurrence, not file size. Poster Poster generates correctly-sized, properly-compressed images automatically from your Google Calendar events and posts them across every platform you connect. One-time setup, then it runs itself.