Explainers
Three arguments that would not fit under the control bar
The resizer has one line of space to justify each decision it makes. These are the three decisions where one line is not enough.
A tool that makes a decision for you owes you the decision it made, and the control bar prints one line about each: which filter ran, which axis got capped, what the ratio actually is now. One line is the right length for a readout and the wrong length for an argument. These three pages are where the arguments went.
They are about this resizer rather than about resizing in the abstract, so the worked examples use the numbers you would actually type — a 3:2 photograph into a 4:3 box, 4000 pixels down to 800, 3.5 cm at 300 dots to the inch. Each one also says where the tool stops, which is the part a feature list will never tell you.
- 01
Pixels and print size
Read this one when a form has asked you for centimetres and this page only offers pixels. The resolution figure stored in an image file is a note about paper, not a property of the picture, and moving it changes nothing you can see on a screen.
- 02
Fit, cover and stretch
Your photograph is one shape and the box you typed is another, and only three things can give way: the numbers, part of the frame, or everybody's proportions. One photograph put through all three, with the dimensions that come out of each printed underneath.
- 03
Does resizing lose quality?
Going down, yes, and this is the arithmetic of how much. Why the picture is halved repeatedly before the final pass instead of jumping straight to the target, what aliasing looks like when it is not done that way, and why the trip back up hands you a bigger file rather than a better one.
- 04
Staged downscaling: the evidence
The measurement behind that argument: one test picture reduced 4:1 and 8:1 by staged halvings, by one Lanczos3 pass and by the browser's own scaler, each scored against the exact average — with a lab that reruns it in your browser.
What is deliberately not here
There is no piece on making something small into something detailed. Enlarging in the resizer is interpolation, and the page measures how much of the result was invented; upscale image runs an AI model on your device instead and labels what it draws as reconstructed, not recovered. A folder of pictures is a job the site does too — bulk resize applies one rule to all of them and hands back a ZIP.
If you came looking for the tool itself, it is on the front page, and the four sizes typed often enough to have been pre-loaded are 1920 × 1080, 1280 × 720, 1080 × 1080 and 800 × 600.