How much can I compress an image without visible quality loss?

Photographs typically compress by 60–90% with no visible difference at normal viewing size, by converting to WebP at 75–85% quality and resizing to the display dimensions.

Is it safe to compress sensitive images online?

Only if the tool is client-side. FileLocally processes files entirely in your browser, so images never leave your device — unlike upload-based compressor sites.

Why is my PNG so much larger than a JPG of the same photo?

PNG is a lossless format designed for graphics with sharp edges, not photographs. For photos it stores far more data than the eye can use; converting to WebP or JPG typically cuts size by 80% or more.

Home › Blog › How to Compress Images Without Losing Quality (2026 Guide)

How-to guide

How to Compress Images Without Losing Quality (2026 Guide)

By FileLocally Editorial · Published 15 July 2026 · Reviewed for accuracy

Quick answer: Convert photos to WebP at 75–85% quality for the biggest savings with no visible loss. Resize images to the dimensions they'll actually be displayed at before compressing — oversizing is the #1 cause of bloated images.

What "losing quality" actually means

Lossy compression discards image data your eye is least sensitive to — subtle colour variations in busy textures, for example. "No visible quality loss" means choosing settings where the discarded data stays below the threshold of human perception at normal viewing size. That threshold is much more forgiving than most people assume, which is why a 4 MB photo can usually become a 400 KB one that looks identical.

The three levers that control file size

1. Dimensions (the big one)

An image displayed at 800px wide but saved at 4000px wide is carrying 25× more pixels than needed. Resize first; everything else is secondary.

2. Format

WebP beats JPG by 25–35% at equal quality and beats PNG massively for photographic content. See our format comparison.

3. Quality setting

The quality slider maps to how aggressively data is discarded. The relationship is not linear — dropping from 100% to 85% often halves the file with no visible change, while 85% to 70% saves less and starts to show on close inspection.

Step-by-step: compress in your browser (no upload)

Open the FileLocally compressor. Files are processed locally — a real difference from upload-based sites if you're handling ID documents, client work or private photos.
Drag your images in. Each appears with its current size.
Choose WebP output and set quality to 80%. Watch the live savings estimate update.
Click Convert & Compress, then download. Compare against the original at 100% zoom — if you can't spot the difference, try 70% and check again.

Recommended settings by use case

Use case	Format	Quality	Typical saving
Website photos / blog images	WebP	75–82%	70–90%
E-commerce product shots	WebP	82–88%	60–80%
Email attachments	JPG or WebP	70–80%	70–90%
Screenshots with text	PNG	lossless	varies
Archival / print masters	PNG	lossless	—

Mistakes to avoid

Compressing the same image repeatedly. Each lossy save compounds artefacts. Always work from the original.
Using PNG for photographs. PNG is lossless, so photos become enormous with no visible benefit.
Trusting "compressed" filenames. Verify actual byte sizes — FileLocally shows before/after totals and the percentage saved.

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