ガイド
ブログ・Webアップロード向け画像圧縮の最適設定
Web掲載用画像で使いやすい圧縮設定の基準をまとめた実践ガイドです。
毎回設定を悩むより、画像タイプごとの基準を決める方が効率的です。品質のばらつきも減らせます。
Set baseline quality by image type
Photos usually work well with medium compression, while screenshots may need slightly higher quality to keep text readable.
Create one baseline for photos and one for text-heavy images so uploads stay consistent.
Use dimension limits before quality tuning
File size drops faster when dimensions match layout width.
For many websites, right-sizing dimensions saves more bytes than aggressive quality reduction.
Recommended practical starting points
Use these as starting values, then adjust based on visual checks.
- Blog photos: JPG/WebP around medium-high quality.
- Screenshots with text: keep quality a bit higher.
- Small UI graphics: compare PNG and WebP before choosing.
- Hero images: test on mobile first.
Check file size targets per placement
Different placements can handle different weight limits.
Set rough targets for thumbnails, inline images, and hero visuals so uploads stay predictable.
Build a simple upload checklist
A repeatable checklist keeps quality and performance aligned across teammates.
- Resize to real display width.
- Apply baseline compression setting.
- Review quickly on desktop and mobile.
- Publish the smallest clear version.
Use this when
- You want a default quality starting point for uploads.
- Your blog images are inconsistent from post to post.
- You need lightweight files for mobile visitors.
- You are documenting a team image workflow.
Start with defaults, then adjust
Good defaults reduce decision fatigue. Begin with a practical range, then raise or lower quality only when a specific image needs it.