Updated · how we check
Resize a photo to 12×18 in (3600×5400 pixels)
A 12×18 in print at 300 DPI is 3600×5400 pixels. Set 12×18 in and 300 DPI in the panel and choose crop to fill: a 4:3 phone photo loses 50% and gives only 168 pixels per inch, so it is enlarged 1.79×. As a JPEG, a detailed outdoor photo comes to about 5.06 MB at the panel's default quality 85 and 3.83 MB at quality 75 (extrapolated). At 19.4 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.
12×18 in at 300 DPI (3600×5400 px)
JPG · no file-size limit · 12x18 in 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. 12x18 in at 300 DPI is 3600x5400 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.
12×18 in at a glance
| Physical size | 12×18 in = 304.8×457.2 mm |
|---|---|
| Pixels at 300 DPI | 3600×5400 px (19,440,000 pixels, 19.4 MP) |
| Shape | 2:3, portrait (width ÷ height = 0.6667) |
| From a 12 MP phone photo | 168 pixels per inch after the crop to fill (50% cut) |
| At 600 DPI | 7200×10800 px (77.8 MP) |
| Estimated JPEG (outdoor photo, quality 75, 300 DPI) | 3.83 MB (extrapolated) |
| JPEG without a KB limit (panel default, quality 85) | 5.06 MB (extrapolated) |
| On iPhone and iPad | Above the 16.7 MP canvas limit of their browsers: make this size on a computer |
How 12×18 in turns into pixels
An inch is exactly 25.4 mm, so at 300 DPI the pixel size is 12 in × 300 = 3600 px wide and 18 in × 300 = 5400 px tall. 12×18 in is a portrait shape with sides in the ratio 2:3 (0.6667 as a decimal), 304.8×457.2 mm in the other unit.
The same 12×18 in needs 2400×3600 px at 200 DPI and 7200×10800 px (77.8 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 12×18 in.
Is your photo sharp enough for 12×18 in?
After the crop to fill, this is how many source pixels land on each inch of 12×18 in. 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 12×18 in | To reach 300 DPI |
|---|---|---|---|---|
| 12 MP phone photo (4032×3024, 4:3) | 2016×3024 (left and right cut) | 50% | 168 DPI | enlarged (1.79×) |
| 24 MP camera photo (6000×4000, 3:2) | 2667×4000 (left and right cut) | 55.6% | 222 DPI | enlarged (1.35×) |
| Full HD screenshot (1920×1080, 16:9) | 720×1080 (left and right cut) | 62.5% | 60 DPI | enlarged (5×) |
| Vertical phone video frame (1080×1920, 9:16) | 1080×1620 (top and bottom cut) | 15.6% | 90 DPI | enlarged (3.33×) |
12×18 in in pixels at each print resolution
Pixels = inches × 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 | 1800×2700 | 4.86 MP | ≈ 1.12 MB | ≈ 1.81 MB |
| 200 DPI | 2400×3600 | 8.64 MP | ≈ 1.87 MB | ≈ 3.04 MB |
| 300 DPI | 3600×5400 | 19.4 MP | ≈ 3.83 MB | ≈ 6.33 MB |
| 400 DPI | 4800×7200 | 34.6 MP | ≈ 6.38 MB | ≈ 10.6 MB |
| 600 DPI | 7200×10800 | 77.8 MP | ≈ 13.1 MB | ≈ 22.1 MB |
How large is a 12×18 in file?
Saved at 300 DPI (3600×5400 px), a detailed outdoor photo of 12×18 in comes to about 2.94 MB at JPEG quality 60, 3.83 MB at 75 and 6.33 MB at 90, and about 3.09 MB as WebP at 75. Dropping to 200 DPI (2400×3600 px) brings quality 75 down to about 1.87 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 30. Set the KB limit next to the size and PixelFit picks the highest quality that fits.
Other 2:3 print and photo sizes
These sizes have the same 2:3 shape as 12×18 in, so a photo cropped for one fits the others with no further crop.
| Size | Pixels | Scale from 12×18 in |
|---|---|---|
| 8×12 inch print | 2400×3600 | 0.67× |
| 20×30 inch print | 6000×9000 | 1.67× |
| 4×6 inch print | 1200×1800 | 0.33× |
| 2×3 inch print | 600×900 | 0.17× |
| 1000×1500 portrait | 1000×1500 | 0.28× |
| 800×1200 portrait | 800×1200 | 0.22× |
| 400×600 portrait | 400×600 | 0.11× |
How to resize a picture to 12×18 in
-
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.
-
Set the size
Pick inch as the unit, enter 12×18 in and 300 DPI; the tool turns that into 3600×5400 pixels.
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Choose how it fits
Choose crop to fill to keep the 2:3 frame without stretching (a phone photo loses 50%, left and right cut). Fit inside keeps the whole picture as a 3600×2700 file instead; Pad with colour puts that on a full 3600×5400 canvas.
-
Pick the format and download
Keep JPG (without a KB limit PixelFit saves at quality 85, about 5.06 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
- 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 12×18 in?
Open the photo in the PixelFit panel on this page, set 12×18 in at 300 DPI (3600 × 5400 px), choose crop to fill and download. From a 12 MP phone photo that crops 50% (left and right cut) and leaves 168 pixels per inch, so the crop is enlarged 1.79×.
How many pixels is 12×18 in?
12×18 in is 3600×5400 px at 300 DPI, 7200×10800 px at 600 DPI and 1800×2700 px at 150 DPI (pixels = inches × DPI).
What DPI should a 12×18 in photo have?
PixelFit uses 300 DPI, which makes 12×18 in exactly 3600×5400 px; print it at 100% scale. At 150 DPI the same 3600×5400 pixels would print 24×36 in, twice as large and with half the density.
How big is a 12×18 in JPEG at 300 DPI?
For a detailed outdoor photo about 3.83 MB at quality 75 (2.94 MB at 60, 6.33 MB at 90, 5.06 MB at the panel's default quality 85); a head-and-shoulders portrait is about 1.4 MB at quality 75, extrapolated from encodes of real sample photos measured up to 6.75 MP (3600×5400 px lies outside that range).
Related
Same 2:3 ratio
Nearby sizes
- A3 (297×420 mm) 3508:4961 (1:1.41)
- 11×14 inch print 11:14
- 16×20 inch print 4:5
- US Legal (8.5×14 in) 17:28
- A4 (210×297 mm) 620:877 (1:1.41)
- 4000×4000 square 1:1