Resize Image
Change image width and height in your browser
Resize Image — what it does
Change an image's width and height in the browser, with an option to keep the aspect ratio locked so one dimension follows the other automatically. Resizing is the most effective size reduction available: a photo at half the width and height carries a quarter of the pixels.
When this tool helps
- Cutting a camera-sized photo down to the dimensions a web page actually displays.
- Meeting a fixed pixel requirement for an avatar, banner or upload form.
- Preparing a smaller version of an image for email or a document.
How to use it
- Choose the image.
- Enter the target width or height.
- Keep aspect ratio locked unless you need exact dimensions.
- Process and download the resized image.
Accuracy, limits, and good practice
- Unlocking the aspect ratio lets you type both dimensions, and any pair that does not match the original ratio will stretch the picture.
- Downscaling is clean; upscaling interpolates and softens, so start from the largest original you have.
- Serve images at roughly the size they display, allowing for double-resolution screens — anything beyond that is bandwidth spent on pixels nobody sees.
Frequently asked questions
What size should a web image be?
Match the display width, or twice it for high-density screens. A full-width hero rarely needs more than about 2000 pixels.
Does resizing reduce the file size?
Substantially. Removing pixels removes data, usually far more effectively than adjusting compression quality alone.
Can I resize many images at once?
Yes, the batch image resizer applies one setting to a whole selection and returns a ZIP.
Related tools on this site
- QR Code Generator — Create a downloadable QR code for text or URLs
- Images to PDF — Combine JPG, PNG, and WebP images into one PDF
- PDF Header & Footer — Add page-aware header or footer text
Everything above runs inside this page. Resize Image needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
調整圖片尺寸能做什麼
在瀏覽器中修改圖片的寬與高，可鎖定長寬比讓另一邊自動跟隨。縮放是最有效的減重手段：寬高各減半的照片，像素只剩四分之一。
什麼時候用得上
- 把原始尺寸的相機照片，縮到網頁實際顯示的大小。
- 符合頭像、橫幅或上傳表單的固定像素要求。
- 為郵件或文件準備較小的圖片版本。
使用步驟
- 選擇圖片。
- 輸入目標寬度或高度。
- 除非需要精確尺寸，否則請保持鎖定長寬比。
- 執行處理並下載縮放後的圖片。
精確度、限制與實務建議
- 解除長寬比鎖定後兩邊都能填，但只要與原始比例不符就會把畫面拉變形。
- 縮小很乾淨；放大是內插、會變糊，所以請從手上最大的原檔開始。
- 圖片以接近顯示尺寸提供即可（高密度螢幕算兩倍），超過的部分都是花在沒人看得到的像素上的頻寬。
常見問題
網頁圖片該多大？
與顯示寬度相同，高密度螢幕則取兩倍。整頁寬的主視覺很少需要超過約 2000 像素。
縮放會讓檔案變小嗎？
會大幅變小。減少像素等於減少資料，通常比單純調整壓縮品質有效得多。
可以一次縮放很多張嗎？
可以，批量圖片縮放工具會用同一組設定處理整批並回傳 ZIP。
本站相關工具
- QR Code 產生器 — 將文字或網址製作成可下載的 QR Code
- 圖片轉 PDF — 將 JPG、PNG、WebP 圖片合併成一個 PDF
- PDF 頁眉與頁尾 — 加入支援頁碼變數的頁眉或頁尾
以上步驟全部在這個頁面內完成，調整圖片尺寸 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。