Two ways to resize
Pixels mode is for when a form, website or print shop asks for exact dimensions. Type the width, and with Lock aspect ratio ticked the height fills in automatically so the picture is not squashed. Untick it only when you genuinely need a fixed frame — for example a 1080 × 1080 Instagram square from a 4:3 photo — and accept that the image will be stretched slightly. If you need to crop instead of stretch, crop first in your phone’s gallery app and then resize here.
Percentage mode is quicker when you simply want something smaller for email or a chat app. 50% halves both width and height, which reduces the pixel count by 75%. The hint under the field shows the resulting dimensions before you commit.
Presets and where they come from
- Passport 413 × 531 px — a 35 × 45 mm photo at 300 DPI, which matches Indian passport and visa requirements and many Schengen forms. Pixel size = millimetres ÷ 25.4 × DPI, so 35 ÷ 25.4 × 300 ≈ 413.
- Instagram 1080 × 1080 px — the square post size Instagram serves at full resolution. Portrait posts use 1080 × 1350 and stories 1080 × 1920.
- HD 1280 × 720 px — YouTube thumbnails (minimum), blog headers and presentation slides.
- Full HD 1920 × 1080 px — desktop wallpapers, video frames and hero banners on websites.
After choosing a preset you can still edit either box.
Downscaling versus upscaling
Reducing size is safe: the browser averages several source pixels into each output pixel, which keeps edges clean and often makes phone photos look sharper on screen. Enlarging is different. New pixels have to be guessed from their neighbours, so a 640 px image blown up to 1920 px will look soft no matter which tool you use. The tool warns you when the output exceeds the original in either dimension. If you must upscale, keep it under 150–200% and use PNG or a high JPEG quality so compression does not add blur on top of interpolation.
Format and quality
The output format defaults to the input format. Change it when:
- You are resizing a PNG screenshot for the web and do not need transparency — JPEG or WebP will be far smaller.
- You are preparing a logo or graphic with a transparent background — keep PNG or choose WebP.
- A form specifies the format, as many online applications do (“JPG only, 20–50 KB”).
The quality slider applies only to JPEG and WebP. 90 is the default here because resizing is usually done to meet a dimension requirement, not a size one; if the file is still too large, drop it to 70–80 or run the result through the image compressor.
Worked example
You have a 3024 × 4032 portrait photo (11 MB) and an exam form wants 200 × 230 px under 50 KB. Enter width 200 with the ratio locked: height becomes 267. Untick the lock and set the height to 230 — the 14% vertical squeeze is barely visible on a face photo and satisfies the form. Choose JPEG at quality 85; the output is about 15 KB.
Frequently asked questions
Will resizing reduce image quality?
Downscaling keeps quality well. Upscaling beyond the original size makes the image softer because new pixels are interpolated.
What size is a passport photo in pixels?
For a 35 × 45 mm Indian passport photo at 300 DPI, use 413 × 531 pixels. Many online forms ask for 200 × 230 px — check the specific requirement.