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Resize a photo to 297×420 mm (3508×4961 pixels)
A 297×420 mm print at 300 DPI is 3508×4961 pixels. Set 297×420 mm and 300 DPI in the panel and choose crop to fill: a 4:3 phone photo loses 47% and gives only 183 pixels per inch, so it is enlarged 1.64×. As a JPEG, a detailed outdoor photo comes to about 4.59 MB at the panel's default quality 85 and 3.48 MB at quality 75 (extrapolated). At 17.4 megapixels this is above the 16.7-megapixel canvas limit of iPhone and iPad browsers, so PixelFit cannot make a file this large there: make it on a computer.
297×420 mm at 300 DPI (3508×4961 px)
JPG · no file-size limit · 297x420 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. 297x420 mm at 300 DPI is 3508x4961 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.
297×420 mm at a glance
| Physical size | 297×420 mm = 11.69×16.54 in |
|---|---|
| Pixels at 300 DPI | 3508×4961 px (17,403,188 pixels, 17.4 MP) |
| Shape | 99:140 (1:1.41), portrait (width ÷ height = 0.7071) |
| From a 12 MP phone photo | 183 pixels per inch after the crop to fill (47% cut) |
| At 600 DPI | 7016×9921 px (69.6 MP) |
| Estimated JPEG (outdoor photo, quality 75, 300 DPI) | 3.48 MB (extrapolated) |
| JPEG without a KB limit (panel default, quality 85) | 4.59 MB (extrapolated) |
| On iPhone and iPad | Above the 16.7 MP canvas limit of their browsers: make this size on a computer |
How 297×420 mm turns into pixels
An inch is exactly 25.4 mm, so at 300 DPI the pixel size is 297 mm ÷ 25.4 × 300 = 3507.874, rounded to 3508 px wide, and 420 mm ÷ 25.4 × 300 = 4960.63, rounded to 4961 px tall. 297×420 mm is a portrait shape with sides in the ratio 99:140 (1:1.41) (0.7071 as a decimal), 11.69×16.54 in in the other unit.
The same 297×420 mm needs 2339×3307 px at 200 DPI and 7016×9921 px (69.6 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 297×420 mm.
Where 297×420 mm is used
Each line comes from the reference listed under Sources, checked October 2026.
- A3 paper is 297 × 420 mm.
Is your photo sharp enough for 297×420 mm?
After the crop to fill, this is how many source pixels land on each inch of 297×420 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 297×420 mm | To reach 300 DPI |
|---|---|---|---|---|
| 12 MP phone photo (4032×3024, 4:3) | 2138×3024 (left and right cut) | 47% | 183 DPI | enlarged (1.64×) |
| 24 MP camera photo (6000×4000, 3:2) | 2828×4000 (left and right cut) | 52.9% | 242 DPI | enlarged (1.24×) |
| Full HD screenshot (1920×1080, 16:9) | 764×1080 (left and right cut) | 60.2% | 65 DPI | enlarged (4.59×) |
| Vertical phone video frame (1080×1920, 9:16) | 1080×1527 (top and bottom cut) | 20.5% | 92 DPI | enlarged (3.25×) |
297×420 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 detailed outdoor photo saved as JPEG.
| Resolution | Pixels | Megapixels | JPEG q75 | JPEG q90 |
|---|---|---|---|---|
| 150 DPI | 1754×2480 | 4.35 MP | ≈ 1.02 MB | ≈ 1.64 MB |
| 200 DPI | 2339×3307 | 7.74 MP | ≈ 1.7 MB | ≈ 2.76 MB |
| 300 DPI | 3508×4961 | 17.4 MP | ≈ 3.48 MB | ≈ 5.73 MB |
| 400 DPI | 4677×6614 | 30.9 MP | ≈ 5.79 MB | ≈ 9.62 MB |
| 600 DPI | 7016×9921 | 69.6 MP | ≈ 11.9 MB | ≈ 20 MB |
How large is a 297×420 mm file?
Saved at 300 DPI (3508×4961 px), a detailed outdoor photo of 297×420 mm comes to about 2.66 MB at JPEG quality 60, 3.48 MB at 75 and 5.73 MB at 90, and about 2.82 MB as WebP at 75. Dropping to 200 DPI (2339×3307 px) brings quality 75 down to about 1.7 MB, but the print then holds fewer pixels per inch.
At 300 DPI the photo does not fit under 200 KB, 500 KB and 1 MB even at quality 30; it fits under 2 MB up to quality 36. Set the KB limit next to the size and PixelFit picks the highest quality that fits.
Sizes close to 297×420 mm
No other target in the PixelFit list has exactly 99:140. The nearest sizes (by pixel count and shape) and their crop from a 3508×4961 image:
- 12×18 inch print: 2:3, 5.7% cropped (left and right cut), then 1.089× scale.
- 11×14 inch print: 11:14, 10% cropped (top and bottom cut), then 0.941× scale.
- A4 (210×297 mm): 620:877 (1:1.41), scale only, then 0.707× scale.
- 16×20 inch print: 4:5, 11.6% cropped (top and bottom cut), then 1.368× scale.
How to resize a picture to 297×420 mm
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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 297×420 mm and 300 DPI; the tool turns that into 3508×4961 pixels.
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Choose how it fits
Choose crop to fill to keep the 99:140 (1:1.41) frame without stretching (a phone photo loses 47%, left and right cut). Fit inside keeps the whole picture as a 3508×2631 file instead; Pad with colour puts that on a full 3508×4961 canvas.
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Pick the format and download
Keep JPG (without a KB limit PixelFit saves at quality 85, about 4.59 MB for a detailed outdoor photo) so the 300 DPI stamp travels with the file, or choose PDF to get the picture as a PDF page, then download.
Sources
- Paper size (ISO 216 and North American sizes), Wikipedia, checked 31 October 2026: en.wikipedia.org/wiki/Paper_size
- 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 Hartz Lake at Hartz Mountain.jpg by JustinH (Wikimedia Commons user) (CC0 1.0): commons.wikimedia.org/wiki/File:Hartz_Lake_at_Hartz_Mount…
Frequently asked questions
How do I resize a photo to 297×420 mm?
Open the photo in the PixelFit panel on this page, set 297×420 mm at 300 DPI (3508 × 4961 px), choose crop to fill and download. From a 12 MP phone photo that crops 47% (left and right cut) and leaves 183 pixels per inch, so the crop is enlarged 1.64×.
How many pixels is 297×420 mm?
297×420 mm is 3508×4961 px at 300 DPI, 7016×9921 px at 600 DPI and 1754×2480 px at 150 DPI (pixels = mm ÷ 25.4 × DPI).
What DPI should a 297×420 mm photo have?
PixelFit uses 300 DPI, which makes 297×420 mm exactly 3508×4961 px; print it at 100% scale. At 150 DPI the same 3508×4961 pixels would print 23.39×33.07 in, twice as large and with half the density.
How big is a 297×420 mm JPEG at 300 DPI?
For a detailed outdoor photo about 3.48 MB at quality 75 (2.66 MB at 60, 5.73 MB at 90, 4.59 MB at the panel's default quality 85); a head-and-shoulders portrait is about 1.26 MB at quality 75, extrapolated from encodes of real sample photos measured up to 6.75 MP (3508×4961 px lies outside that range).
Related
Nearby sizes
- 12×18 inch print 2:3
- 11×14 inch print 11:14
- A4 (210×297 mm) 620:877 (1:1.41)
- 16×20 inch print 4:5
- 4000×4000 square 1:1
- US Legal (8.5×14 in) 17:28