Thumbnails are scaled-down versions of larger photographs, useful for conserving screen space on a Web page or visually scanning a photo archive for a specific shot. They don't have a standard size -- thumbnails for a portfolio might be much larger than thumbnails for your LinkedIn profile. Facebook, for instance, uses three thumbnail dimensions, depending on where your image appears. Free online programs can help you take any image and reduce its size to a thumbnail.
Click "Choose a File." Browse to and select the image you want; it needs to be a JPEG or PNG file smaller than 1MB.
Click the "Select a Thumbnail Size" menu to choose how big you want your thumbnail.
Click the "Make a Thumbnail" button.
Copy the URL, HTML or BBCode and use it online. Right-click the thumbnail and click "Save Image As" to save the thumbnail to your computer.
Click "Choose File" and browse to and select your image. Click "Upload Image."
Slide the top slider between "small" and "big." You can see your image resize. Use the included guides to estimate the resulting width and height, or use the Width and Height boxes to enter in exact values.
Select the output file format in the Save As box; you can choose JPG, GIF or PNG. You can also choose the file quality and whether you want to crop or rotate the image. The image preview changes so you can see your selections.
Select the "Sharpen" box if you are severely reducing an image. Sharpening helps reduce the resulting fuzziness.
Click "Resize My Image" when you have made all your selections. After your file is uploaded, click the "Click to Continue" link.
Right-click the image and select "Save Image As" to save the image to your computer. Resizr.com periodically deletes images from the server.
Click "Browse" to select a picture from your computer. To select an online image, click "From Web" and type in the URL. Click "Continue."
Use the "Crop" and "Rotate" menus to crop and rotate your image, if desired.
Click the "Make My Picture" menu and select "Custom Size." Type in your desired width in the Width box. Click outside of the box; the estimated final size of your image is listed in pixels.
Select any special effects you want to apply to your image in the Choose Special Effects section.
Choose your image format (JPG, GIF, PNG or BMP). If you select "JPG," you can also choose the quality and the maximum file size.
Click "I'm Done, Resize My Picture."
Click "Save to Disk" to save the image to your computer. Click "Save to Web" to post the picture on social media sites. The image is deleted off PicResize's servers in 20 minutes.
Reducing the file size means that your image has fewer pixels than it did before, which means the thumbnail might look blurry. Use sharpening tools if your image resizer has them or choose a higher quality for the output file.
JPG files compress badly when you output them as JPG. Start with a PNG or GIF image, or choose a different file format for your thumbnail if you are starting with a JPG image.
Save your thumbnail under a new filename to avoid overwriting the original file.