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Resize a photo to 40×50 mm (472×591 pixels)
A 40×50 mm print at 300 DPI is 472×591 pixels. Set 40×50 mm and 300 DPI in the panel and choose crop to fill: a 4:3 phone photo loses 40.1% and still gives 1,534 pixels per inch. As a JPEG, a head-and-shoulders portrait comes to about 49.6 KB at the panel's default quality 85 and 37.5 KB at quality 75.
40×50 mm at 300 DPI (472×591 px)
JPG · no file-size limit · 40x50 mm at 300 DPI · white background
No file-size limit is set: PixelFit saves at high quality and changes only the format and any pixel size you set. 40x50 mm at 300 DPI is 472x591 pixels.
Fit, background and padding crop to fill · white background
Saving presets is part of Pro.
The result appears here: the exact byte count, pixel size and quality, the size before and after, a preview and a download button.
The batch kit (one ZIP for up to 500 photos, several photos merged into one PDF) is part of Pro.
40×50 mm at a glance
| Physical size | 40×50 mm = 1.57×1.97 in |
|---|---|
| Pixels at 300 DPI | 472×591 px (278,952 pixels, 0.28 MP) |
| Shape | 4:5, portrait (width ÷ height = 0.8) |
| From a 12 MP phone photo | 1,534 pixels per inch after the crop to fill (40.1% cut) |
| Copies per sheet | 6 on 4×6 in · 28 on A4 · 25 on US Letter |
| At 600 DPI | 945×1181 px (1.12 MP) |
| Resampling passes from a phone photo | 2415×3024 crop → 1207×1512 → 603×756 → 472×591 |
| Estimated JPEG (portrait photo, quality 75, 300 DPI) | 37.5 KB |
| JPEG without a KB limit (panel default, quality 85) | 49.6 KB |
How 40×50 mm turns into pixels
An inch is exactly 25.4 mm, so at 300 DPI the pixel size is 40 mm ÷ 25.4 × 300 = 472.441, rounded to 472 px wide, and 50 mm ÷ 25.4 × 300 = 590.551, rounded to 591 px tall. 40×50 mm is a portrait shape with sides in the ratio 4:5 (0.8 as a decimal), 1.57×1.97 in in the other unit.
The same 40×50 mm needs 315×394 px at 200 DPI and 945×1181 px (1.12 MP) at 600 DPI. PixelFit writes the DPI you set into the JPEG header (the JFIF density field), so print software that reads it knows the file is meant to come out at 40×50 mm.
Is your photo sharp enough for 40×50 mm?
After the crop to fill, this is how many source pixels land on each inch of 40×50 mm. Above 300 DPI the picture is reduced to 300 DPI; below it, PixelFit has to enlarge the crop and fine detail softens.
| Starting image | Crop to fill keeps | Area lost | Pixels per inch at 40×50 mm | To reach 300 DPI |
|---|---|---|---|---|
| 12 MP phone photo (4032×3024, 4:3) | 2415×3024 (left and right cut) | 40.1% | 1,534 DPI | reduced (0.2×) |
| 24 MP camera photo (6000×4000, 3:2) | 3195×4000 (left and right cut) | 46.8% | 2,029 DPI | reduced (0.15×) |
| Full HD screenshot (1920×1080, 16:9) | 863×1080 (left and right cut) | 55.1% | 548 DPI | reduced (0.55×) |
| Vertical phone video frame (1080×1920, 9:16) | 1080×1352 (top and bottom cut) | 29.6% | 686 DPI | reduced (0.44×) |
40×50 mm in pixels at each print resolution
Pixels = millimetres ÷ 25.4 × DPI. The panel uses 300 DPI unless you change it; the file sizes are for a portrait saved as JPEG.
| Resolution | Pixels | Megapixels | JPEG q75 | JPEG q90 |
|---|---|---|---|---|
| 150 DPI | 236×295 | 0.0696 MP | ≈ 13.6 KB | ≈ 21.6 KB |
| 200 DPI | 315×394 | 0.12 MP | ≈ 20.6 KB | ≈ 33.1 KB |
| 300 DPI | 472×591 | 0.28 MP | ≈ 37.5 KB | ≈ 61.5 KB |
| 400 DPI | 630×787 | 0.5 MP | ≈ 58 KB | ≈ 97.2 KB |
| 600 DPI | 945×1181 | 1.12 MP | ≈ 108 KB | ≈ 192 KB |
Will a 40×50 mm photo fit a KB limit?
Saved at 300 DPI (472×591 px), a head-and-shoulders portrait of 40×50 mm comes to about 29.1 KB at JPEG quality 60, 37.5 KB at 75 and 61.5 KB at 90, and about 22.6 KB as WebP at 75. Dropping to 200 DPI (315×394 px) brings quality 75 down to about 20.6 KB, but the print then holds fewer pixels per inch.
At 300 DPI the photo fits under 20 KB up to quality 31 and under 50 KB up to quality 84; under 100 KB and 200 KB it fits even at quality 95. Set the KB limit next to the size and PixelFit picks the highest quality that fits.
Printing 40×50 mm copies
Without margins or cutting gaps, 6 copies fit on one 4×6 in (102×152 mm) photo print, 28 on an A4 sheet, 25 on US Letter (some turned sideways where that packs more). Print at 100% scale, never "fit to page", or a small ID photo of 40×50 mm comes out the wrong size; 472×591 px at 300 DPI is exact.
Sizes close to 40×50 mm
No other target in the PixelFit list has exactly 4:5. The nearest sizes (by pixel count and shape) and their crop from a 472×591 image:
- 480×640 portrait: 3:4, 6.1% cropped (left and right cut), then 1.084× scale.
- 420×525 px photo: 4:5, 0.2% cropped (top and bottom cut), then 0.89× scale.
- 420×540 px photo: 7:9, 2.5% cropped (left and right cut), then 0.913× scale.
- 35×45 mm passport photo: 7:9, 2.5% cropped (left and right cut), then 0.898× scale.
Forms in the PixelFit directory that ask for 40×50 mm
Matched by the photo size stated in each form's official notice (checked October 2026); open the form's page for its KB limit, background and other rules.
- Hong Kong travel document (HKSAR passport) application photo (Hong Kong passport)
How to resize a picture to 40×50 mm
-
Add the picture
Drop, paste or pick the photo in the PixelFit panel at the top of this page; it is decoded in your browser and never uploaded.
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Set the size
Pick mm as the unit, enter 40×50 mm and 300 DPI; the tool turns that into 472×591 pixels.
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Choose how it fits
Choose crop to fill to keep the 4:5 frame without stretching (a phone photo loses 40.1%, left and right cut). Fit inside keeps the whole picture as a 472×354 file instead; Pad with colour puts that on a full 472×591 canvas.
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Pick the format and download
Keep JPG (without a KB limit PixelFit saves at quality 85, about 49.6 KB for a head-and-shoulders portrait) so the 300 DPI stamp travels with the file, or choose PDF to get the picture as a PDF page, then download.
Sources
- Immigration Department HKSAR: Photograph requirements for travel document, Immigration Department, Hong Kong SAR, checked 31 October 2026: immd.gov.hk/eng/residents/immigration/traveldoc/photorequ…
- Inch (1 inch is exactly 25.4 mm), Wikipedia, checked 31 October 2026: en.wikipedia.org/wiki/Inch
- Measured by PixelFit with sharp 0.35.5 / libvips 8.18.7 on 31 October 2026, from the sample photo President Barack Obama.jpg by Pete Souza (Official White House photo) (Public domain): commons.wikimedia.org/wiki/File:President_Barack_Obama.jpg
Frequently asked questions
How do I resize a photo to 40×50 mm?
Open the photo in the PixelFit panel on this page, set 40×50 mm at 300 DPI (472 × 591 px), choose crop to fill and download. From a 12 MP phone photo that crops 40.1% (left and right cut) and still leaves 1,534 pixels per inch to work with.
How many pixels is 40×50 mm?
40×50 mm is 472×591 px at 300 DPI, 945×1181 px at 600 DPI and 236×295 px at 150 DPI (pixels = mm ÷ 25.4 × DPI).
What DPI should a 40×50 mm photo have?
PixelFit uses 300 DPI, which makes 40×50 mm exactly 472×591 px; print it at 100% scale. At 150 DPI the same 472×591 pixels would print 3.15×3.94 in, twice as large and with half the density.
How many 40×50 mm photos fit on one sheet?
Without margins, 28 fit on A4 (210×297 mm), 25 on US Letter and 6 on a 4×6 in photo print, turning them sideways where that packs more. Leave a few millimetres for cutting.
How big is a 40×50 mm JPEG at 300 DPI?
For a head-and-shoulders portrait about 37.5 KB at quality 75 (29.1 KB at 60, 61.5 KB at 90, 49.6 KB at the panel's default quality 85); a detailed outdoor photo is about 70.6 KB at quality 75, estimated from measured encodes of real sample photos at 472×591 px.
Related
Nearby sizes
- 480×640 portrait 3:4
- 420×525 px photo 4:5
- 420×540 px photo 7:9
- 35×45 mm passport photo 7:9
- 400×514 px photo 200:257 (about 7:9)
- 500×700 portrait 5:7