画像サイズを100KBに縮小するにはどうすればいいですか?
In today’s fast-paced digital world, optimizing image size is essential for faster website loading, quicker sharing, and saving storage space. Whether you’re uploading a profile photo, attaching an image to an email, or compressing images for a blog or e-commerce listing, there are often strict file size limits. A common requirement is to reduce image size to under 100KB, which can be a challenge, especially if you want to retain good quality.
This article explores various effective ways to reduce image size to 100KB without compromising too much on visual quality, now let’s start it.
1. Why You Need to Reduce Image Size to 100KB?
Reducing image file size helps in several scenarios:
- Faster Load Time : Smaller images load faster on websites and improve user experience.
- Storage Management : Reducing size saves disk or cloud storage space.
- Email & Messaging Limits : Email attachments often have size caps; small images ensure delivery.
- Online Form Uploads : Government sites, job applications, and registration forms often require <100KB image uploads.
- SEO & Performance : Smaller images reduce page load time, positively affecting SEO rankings.
But achieving this reduction while maintaining decent quality can be tricky. So let’s break it down.
2. Reduce Image Size to 100KB Using Swyshare Free Online Image Compressor
Swyshare 画像圧縮ツール is a simple yet powerful online tool designed to help you reduce image sizes quickly without compromising quality. Whether you’re dealing with photos, graphics, or screenshots, Swyshare makes compressing your images to under 100KB effortless.
使い方 Swyshare to reduce image size to 100KB:
- Visit the Swyshare Image Compressor website, then drag and drop your image files into the upload area.
- The tool automatically compresses the image and allows you to preview of the original and compressed versions.
- Check the file size displayed – if it’s above 100KB. Once satisfied with the quality and size, download the compressed image to your device.

3. Reduce Image Size to 100KB Using Desktop Software
If you want more control, especially for bulk image processing , desktop apps offer deeper customization and better results.
💻 Software Options:
Photoshop (Paid)
- へ移動 File > Export > Save for Web (Legacy) 。
- Choose JPEG format and adjust quality slider until size is under 100KB.
- Preview image and file size in real-time.
Paint.NET (Free for Windows)
- Open image > File > Save As > Select JPG.
- Use the quality slider to target under 100KB.
- Keep checking the preview until it meets your requirement.
GIMP (Free, Cross-platform)
- Open image > ファイル > 名前を付けてエクスポート > Choose JPG/PNG.
- Adjust compression level (e.g., 80% for JPG).
- Check estimated file size before saving.
ImageOptim (Mac)
- Drag images into the app.
- It automatically compresses using smart algorithms.
- Best for macOS users looking for quick, lossless compression.

4. Reduce Image Size to 100KB Using Mobile Apps
When you’re on the go, mobile apps can help you compress images directly from your device.
Android:
- Photo Compress 2.0 – Resize and reduce file size to a target threshold.
- Lit Photo Compress & Resize – Offers batch resizing and percentage-based compression.

iOS:
- Compress Photos & Pictures – Select images and reduce to a size like 100KB.
- Image Size – Resize by dimensions or file size, preview before saving.

5. Adjust Dimensions and Format for Better Compression
Reducing the 解決 または changing the image format can make a huge difference in file size.
Reduce Resolution:
- An image with 4000×3000 resolution will be large. Resize it to something like 1024×768 or 800×600 before compressing.
- Online tools like Simple Image Resizer または ILoveIMG allow resizing by pixel dimensions.

Change File Format:
- 変換する PNG に JPG : PNGs are lossless but heavier. JPGs offer smaller size at acceptable quality.
- Use ウェブP : Google’s WebP format maintains high quality at much lower sizes (but not all platforms support it).
6. Reduce Image Size to 100KB with Microsoft Tools
If you don’t want third-party apps:
Microsoft Paint (Windows):
- Open the image, click Resize and choose percentage or pixel value.
- Save As JPG and check size, repeat until you hit 100KB.

Outlook / Word:
When inserting images into Microsoft Office:
- Use Compress Pictures option.
- 選ぶ E-mail (96 ppi) または Web (150 ppi) compression options.

7. 結論
Reducing an image size to 100KB is essential for faster uploads, efficient storage, and improved online performance. While there are many tools available, Swyshare 画像圧縮ツール stands out as an excellent free choice for anyone looking to quickly and easily compress images without sacrificing quality. Its drag-and-drop simplicity, instant preview, and effective compression algorithms make it perfect for both beginners and professionals alike. Whether you need to optimize a single photo or several images, Swyshare offers a fast, reliable, and user-friendly solution to get your images under 100KB with minimal effort. Give Swyshare a try and experience hassle-free image compression today!