By pixels or by percentage
Resizing by pixels is what you need when a website, a form or a template tells you the exact size: a banner that must be 1200 px wide, an avatar that should be 400 px tall, or a product photo for a marketplace. Type only the width or only the height and the other side is calculated automatically, so the image keeps its proportions and never looks stretched.
Resizing by percentage is handy when you just want everything smaller. Choose a percentage and every selected image is scaled by that amount, whatever its original size. It's a simple way to shrink a whole folder of phone photos in one go.
By print size: inches, cm or mm with DPI
When the instructions give a printed size, such as a 4 × 6 inch photo or a logo 5 cm wide, switch to the inches/cm mode. Type the width, the height or both in inches, centimeters or millimeters, set the DPI (300 by default), and the tool calculates the pixels: at 300 DPI, 4 inches become 1200 pixels. The DPI is also written into JPG and PNG files, so print programs place the image at that size.
In this mode the image always reaches the size you asked for, enlarging it if needed. Enlarging can't add detail, so start from the biggest original you have.
Smaller dimensions, smaller files
Fewer pixels means less data, so resizing is one of the most effective ways to make images lighter. A full-resolution phone photo is far larger than what a website, an email or a chat window can display, and sending it at that size mostly wastes space.
If you need to hit a specific file size in KB as well, send the result to “Compress image” afterward, without selecting it again. And if the format matters, you can change it here: keep the original format, or save as JPG, PNG or WEBP.
No accidental enlarging
By default ConvertirDocs doesn't make an image bigger than its original dimensions. Enlarging can't add detail that isn't there; it only produces a softer, heavier file. If you really need a larger canvas, for example to match a template, you can ask for it explicitly.
The camera orientation of your photos is respected, so pictures taken in portrait mode come out in portrait mode, and your width and height apply the way you see the image.
Free, private and without an account
The whole resize happens in your browser. Your images are never uploaded to a server and nothing is kept. You don't need to sign up or leave an email, and there's no cap on how many images you can resize: ConvertirDocs is 100% free.
As a bonus for your privacy, the resized images no longer carry EXIF data, which includes the GPS location many phones attach to every photo.