The short version
Use a higher pixel density for posters examined closely and a lower density for large work viewed farther away. Calculate 300, 200 and 150 PPI options, compare them with post-crop source pixels, then follow the print provider's process-specific recommendation.
What matters most
- Large dimensions do not automatically require 300 PPI.
- Viewing distance and source detail affect useful density.
- Printer templates, bleed and scale instructions override generic charts.
How to apply it
- Confirm trim dimensions, orientation and normal viewing distance.
- Obtain the printer's file, bleed, scale and color requirements.
- Calculate several PPI options and required megapixels.
- Compare with the cropped source and avoid unnecessary enlargement.
- Produce a physical-size detail proof before an important large print.
Reference table
| Poster | 300 PPI | 200 PPI | 150 PPI |
|---|---|---|---|
| 11×17 in | 3300 × 5100 | 2200 × 3400 | 1650 × 2550 |
| 18×24 in | 5400 × 7200 | 3600 × 4800 | 2700 × 3600 |
| 20×30 in | 6000 × 9000 | 4000 × 6000 | 3000 × 4500 |
| 24×36 in | 7200 × 10800 | 4800 × 7200 | 3600 × 5400 |
Use exact dimensions and units in production notes; familiar labels can describe more than one standard.
Start with viewing context
A handheld photo print and a wall poster are not viewed in the same way. As distance increases, individual pixels occupy a smaller visual angle, so a lower raster density may appear continuous. Fine typography and inspection-distance artwork remain more demanding.
Define whether viewers will stand close, pass at several feet or see the poster across a room. Use that context to compare density options, then confirm with the printer because device resolution, screening and substrate affect the result.
- Estimate normal and closest viewing distance.
- Consider fine text separately from photographs.
- Follow process-specific printer advice.
Calculate how quickly raster demand grows
A 24×36 poster at 300 PPI requires 7200 × 10800, or 77.76 MP. At 150 PPI it requires 3600 × 5400, or 19.44 MP—one quarter as many pixels because both dimensions are halved.
More pixels increase memory, storage and processing. Do not create a 300-PPI raster solely because it is a familiar number. Choose the density that the content, source and viewing condition can use meaningfully.
- Doubling PPI quadruples pixel count.
- Calculate post-crop requirements.
- Avoid oversized files without visible purpose.
Evaluate source detail with a physical proof
Place a representative section containing texture, edges and text at final physical scale, then print it using the intended process or a close substitute. View it from expected distance and from the closest realistic inspection point.
A monitor zoom percentage is not a physical proof unless display density and scale are controlled. Proofing exposes sharpening halos, noise, interpolation and type-size issues that a whole-poster preview can hide.
- Proof the hardest section.
- View from realistic distance.
- Inspect typography and photographic detail.
Follow production requirements
Some print providers request artwork at a reduced physical scale with proportionally higher effective DPI; others expect full-size files. Use their template, bleed, color profile and maximum-dimension instructions rather than inventing a scaling convention.
Keep important content within safe trim margins, flatten only when requested and verify the final raster. Archive the master separately so another poster size can be generated without scaling the delivered file again.
Common mistakes to avoid
- Upscaling to 300 PPI without evaluating viewing distance.
- Calculating from paper size but omitting bleed.
- Using total megapixels despite an incompatible crop ratio.
- Judging a huge file only while zoomed out on a monitor.
Continue with the right tool
Use a calculator to check the numbers against your own source and destination instead of relying on a generic preset.
Related guides
Cropping vs Resizing an Image: What Actually Changes?
Understand how cropping and resizing affect composition, aspect ratio, pixel dimensions and quality so you can choose the correct operation.
Image cropping and print preparationHow to Crop an Image to an Aspect Ratio Without Stretching
Calculate and position an exact aspect-ratio crop while preserving natural proportions, important content and enough pixels for output.
Image cropping and print preparationHow Much of an Image Will Be Lost When Cropping?
Calculate crop dimensions, removed pixels and percentage area when fitting one image aspect ratio into another without distortion.
Frequently asked questions
Is 150 DPI enough for a poster?
It can be for larger work viewed farther away, but source, subject and printer process should be proofed.
Should every poster be 300 DPI?
No. That can create very large files without visible benefit for distant viewing.
How do I include bleed?
Use the printer's specified extra distance on every required edge and convert that enlarged canvas to pixels.
Can I print a phone photo as a poster?
Possibly. Check post-crop dimensions, focus, noise and expected viewing distance with a physical proof.