ID photo resizer
Resize a photo to real ID-photo specs — 25×35 mm, 33×48 mm, 35×49 mm, 35×45 mm, passport, US visa, Schengen visa and 12 presets in total — at any 72–1200 dpi, with short-edge / long-edge / centre-crop scaling, the exact crop ratio, a JPEG size estimate and local Canvas rendering that never uploads the image.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
JPG / PNG / WebP. The image is processed locally in your browser and never uploaded or logged.
72–1200; ID photos are usually 300 dpi (the official Chinese ID card spec is 350 dpi).
Pick a photo to see the target size and preview
No image selected yet
Size plan
Target pixels, scale and crop ratios plus a size estimate. The estimate is approximate and the real file is usually smaller.
295 × 413 px25.0 × 35.0 mm——47.9 KB—Spec: 1 inch (25 × 35 mm) Target pixels: 295 × 413 px (300 dpi) Physical size: 25.0 × 35.0 mm Scaling: cover the short edge (crop the overflow) Source: no source size given, target geometry only Estimated size: 47.9 KB (JPEG q=0.85)
The size is estimated with the empirical JPEG formula bpp = 0.05 + 0.45·q^1.5. ID photos usually have a plain background, so the real file is often smaller — up to ±50% off.
What this tool does
- Hand in a photo for a form or a document: pick a spec and get the exact pixel size (25×35 mm is 295×413 px at 300 dpi) and physical size without converting millimetres by hand.
- The aspect ratio does not match: "cover the short edge" scales the photo up and crops the overflow, and the tool tells you exactly what percentage is cut horizontally and vertically so you can keep the face in frame.
- The upload limit is tight (many portals cap photos at 20–100 KB): the tool estimates the JPEG size, and if you enter a limit it solves for the quality parameter you probably need.
- Export a ready-to-submit JPEG: scaling, cropping and compression all happen in the local Canvas, nothing is uploaded, and the exported file can be submitted straight away.
Example
Input
1 inch (25 × 35 mm), 300 dpi, source 1200 × 1600 px, cover the short edge, JPEG q=0.85
Output
Spec: 1 inch (25 × 35 mm) Target pixels: 295 × 413 px (300 dpi) Physical size: 25.0 × 35.0 mm Scaling: cover the short edge (crop the overflow) Scale: 25.8% (source 1200 × 1600 px) Crop: horizontally 4.8% / vertically 0.0% (4.8% of the area) Estimated size: 47.9 KB (JPEG q=0.85)
The output matches the Size plan panel on the page. The size is an estimate; a plain-background ID photo is usually smaller than that number.
Frequently asked questions
How many pixels is a 1-inch ID photo?
Pixels depend on the dpi, so there is no single number. 25×35 mm is 295×413 px at 300 dpi (the usual choice) and 344×482 px at 350 dpi. The official Chinese ID card photo is 26×32 mm at 350 dpi, i.e. 358×441 px — which is exactly what this tool computes at 350 dpi.
What is the difference between short edge, long edge and centre crop?
Cover the short edge scales the photo so the short side fills the frame and crops the overflow on the long side: no blank space, but heads or shoulders may be cut (scaling 25.8% and cropping 4.8% horizontally is that case). Keep the long edge whole scales so the long side fits and pads the other side with white: nobody is cropped, but there is blank space. Centre crop does not scale at all — it takes the target aspect ratio from the middle, which crops a lot when the source is much larger.
How accurate is the size estimate?
It is an estimate. JPEG size has no closed-form formula, so the tool uses bytes per pixel bpp = 0.05 + 0.45·q^1.5 (q being the quality parameter) times the pixel count. ID photos have plain backgrounds and little texture, so the real file is usually smaller — up to ±50% off. For the exact number, export once: the page shows the real byte size.
Is the photo uploaded anywhere?
No. Picking, scaling, cropping, compressing and exporting all happen in your browser with Canvas, the page makes no network request, and the image never leaves your device or appears in any log.
I set a size limit but the exported file is still too big. Why?
The tool solves the same empirical formula for a quality parameter between 0.5 and 0.95 and shows it, but the real compression result depends on the image content. If the export is still over the limit, lower the quality slider a little and export again — the page reports the actual byte size each time.
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