Find your quality sweet spot
For most photographs, the magic range sits between 70 and 85 on the quality slider. Inside this band, file sizes routinely drop 60–80% while the image looks identical at normal viewing distance — the discarded data is detail your eyes cannot resolve anyway.
Move the slider and watch the per-image savings update live. The first big drop — from maximum down to about 80 — usually buys the largest savings for zero visible cost. Below 70, scrutinize closely; below 60, expect artifacts in skies, shadows, and smooth gradients.
One more lever: the format itself. A photo at quality 80 as WebP often beats the same photo at quality 90 as JPG — smaller file, equal or better appearance. When chasing maximum quality per byte, switch formats before reaching for a higher slider value.
Match the format to the image
Format choice affects perceived quality as much as the slider. Photographs shine as JPG or WebP; graphics with text, logos, and screenshots stay razor-sharp as PNG. Putting a text-heavy screenshot through aggressive JPG compression is the fastest way to make words look fuzzy.
WebP deserves special mention: at equal visual quality it is typically 25–35% smaller than JPG, with transparency support as a bonus. If your audience uses modern browsers, it is the quality-per-byte champion.
Never recompress a compressed image
Every lossy compression discards data permanently, and compressing an already-compressed JPG discards more — generation loss that accumulates into visible mush. Always compress from the original or highest-quality version you have, never from a previously shrunk copy.
This applies to downloads too: if a platform already compressed your image (social media, messaging apps), compressing that download again compounds the damage. Go back to the source file whenever possible.
Check results at 100% zoom
Thumbnails lie. An image that looks perfect as a small card can reveal blockiness, banding, or smeared detail at full size. Before downloading a batch, open two or three cards at 100% and inspect edges, faces, and text — the areas where artifacts appear first.
Pay special attention to high-contrast edges and smooth gradients: halos around dark-to-light transitions and stair-stepped skies are the telltale signs you pushed one notch too far. Nudge quality up slightly and the whole batch re-processes automatically.
Size the image before compressing
Compression works best on images already at their display size. A 6000px photo shown at 1200px wastes bytes twice: once on pixels nobody sees, once on compressing them. Resize to the target dimensions first, then compress — the quality-per-byte ratio improves dramatically.
The CubTools resize tool pairs perfectly here: bring the image down to display size, then run it through the compressor. Two quick steps, one dramatically leaner file, zero visible difference on the page.
Frequently asked questions
What quality setting looks best?
For photos, 75–85 preserves full visual quality while cutting most of the bytes. Reserve 85+ for detail-critical work and 60–70 for thumbnails or casual sharing.
Does compressing twice hurt quality?
Yes — each lossy pass discards more data. Always compress from the original or highest-quality version, never from an already-compressed copy.
Which format keeps the best quality?
PNG is lossless and pixel-perfect (but large). For photos, WebP at 75–80 gives the best quality per byte; JPG at 80–85 is the universal safe choice.
How do I check quality before downloading?
Open the result cards at 100% zoom and inspect edges, gradients, and text. If you spot blockiness or banding, raise the quality a notch.