Required Resolution Calculator
Use this when you know how large you want the print to be and want to know how many pixels the image needs.
Print size
Start from the size you want the finished print to be. If you already have an image and want to know how large it prints, use the Print Size Calculator instead.
Paper and photo sizes
Target density
Target density is how tightly you want the pixels packed on paper, in pixels per inch. The higher it is, the more pixels the image needs to cover the same size.
300 PPI is a common high-quality print setting, not a universal requirement. The right value depends on the printer, the paper and the viewing distance.
Common densities
Resolution required
2,481 × 3,508
To print 210 × 297 mm with 300 pixels in every inch, the image needs at least 2,481 × 3,508 pixels. An image with fewer pixels than this can still be printed at that size, but the pixels are spread more thinly. Pixel counts are rounded up, so the result always meets or exceeds the density you asked for.
Resolution required, 2,481 by 3,508 pixels.
Print shape
Details
- Megapixels needed8.7 MP
- Exact calculation2,480.31 × 3,507.87Rounded up to whole pixels above
- Density achieved300 PPIMeets or exceeds the target
- Requested size210 × 297 mm
- OrientationPortrait
- PresetA4ISO 216
Formula and assumptions
widthInchesequalsrequested width converted to inches
heightInchesequalsrequested height converted to inches
Pixels needed at the target density
requiredWidthPixelsExactequalswidthInches × targetPPI
requiredHeightPixelsExactequalsheightInches × targetPPI
Rounded up, so the target is always met
requiredWidthPixelsequalsceil(requiredWidthPixelsExact)
requiredHeightPixelsequalsceil(requiredHeightPixelsExact)
Assumptions
- Pixel dimensions are rounded up so the resolution always meets or exceeds the target density.
- 300 PPI is a common high-quality print starting value, not a universal requirement. It is always editable.
- Paper sizes are stored in portrait orientation and swapped on demand.
- The calculation covers geometry only. It does not judge whether an image of that size will look sharp.
Paper sizes used
| Size | Dimensions | Source |
|---|---|---|
| A4 | 210 × 297 mm | ISO 216 |
| A3 | 297 × 420 mm | ISO 216 |
| A5 | 148 × 210 mm | ISO 216 |
| 4 × 6 in | 4 × 6 in | Conventional photographic size |
| 5 × 7 in | 5 × 7 in | Conventional photographic size |
| 8 × 10 in | 8 × 10 in | Conventional photographic size |
A-series sizes are defined in millimetres by ISO 216. The inch sizes are conventional trade sizes rather than a formal standard.
Questions
Why are the pixel figures rounded up?
Rounding down would put the print slightly below the density you asked for. Rounding up guarantees the resolution meets or exceeds the target, at the cost of a fraction of a pixel. This is the one place on the site where rounding is deliberately upward.
How many pixels does an A4 print need at 300 PPI?
A4 is 210 × 297 mm, which is 8.268 × 11.693 inches. At 300 PPI that needs 2481 × 3508 pixels, about 8.7 megapixels.
How do I switch between portrait and landscape?
Use the swap button. Paper sizes are stored once in portrait orientation and swapped on demand, so there is no separate landscape preset to choose.
What if my image has fewer pixels than this?
You can still print it, at a lower effective density. Use the Print Size Calculator to see what physical size your existing pixels reach at a density you are happy with.