Photos
Photo calendar image size: resolution, pixels and aspect ratio
On screen almost every photo looks sharp – printed at A4 or A3 it shows how many pixels it really has. Here is how big photos need to be for a calendar, what a phone photo can do and which aspect ratio suits which layout.
The tool shows a quality indicator for every photo – green from 300 dpi, yellow from 225 dpi, red below.
Check photos and make a calendarHow many pixels you need
For calendars, 300 dpi is the target and 225 dpi the lower limit. The table shows the pixels needed for a photo that fills the whole page or the full width.
| Area | Size | 300 dpi (good) | 225 dpi (still good) |
|---|---|---|---|
| A4 full page | 21 × 29.7 cm | 2480 × 3508 px | 1860 × 2631 px |
| A4 portrait, photo on top (4:3) | 21 × 15.75 cm | 2480 × 1860 px | 1860 × 1395 px |
| A3 full page | 29.7 × 42 cm | 3508 × 4961 px | 2631 × 3720 px |
| 21 × 21 cm full page | 21 × 21 cm | 2480 × 2480 px | 1860 × 1860 px |
| A5 landscape full page | 21 × 14.8 cm | 2480 × 1748 px | 1860 × 1311 px |
In print-shop mode, 3 mm of bleed per side is added – 2551 × 3579 px for a full A4 page. Photos in collages or frames need correspondingly less.
dpi explained simply
dpi means “dots per inch” (2.54 cm). A photo has no fixed dpi – it follows from the printed size:
dpi = pixels ÷ width in inches
A photo 3000 pixels wide has 3000 ÷ 8.27 ≈ 363 dpi at 21 cm wide, but only about 181 dpi at 42 cm. The dpi value stored in the file's properties doesn't matter – only the pixels count.
Zooming costs resolution: enlarging a photo to twice its size to show a detail halves the dpi. The tool's indicator takes that into account.
What phone photos can do
A typical 12-megapixel phone photo has 4032 × 3024 pixels. Printed full page that gives:
| Format | dpi | Result |
|---|---|---|
| A5 landscape | about 488 | Very good |
| 21 × 21 cm | about 366 | Very good |
| A4 | about 345 | Good |
| A3 | about 244 | Still good, details slightly softer |
Phones with 48 megapixels or more usually save smaller photos by default, often 12 or 24 megapixels. For A3, use the full-resolution mode or a camera if you can.
Where photos quietly get small
- Messengers: photos sent via WhatsApp and the like are usually scaled down and compressed. Ask for the original – as a file or through a shared folder.
- Social networks: downloads from Instagram or Facebook are scaled down too.
- Screenshots only have the screen's resolution.
- Digital zoom and cropping in the gallery app reduce the pixels.
- Editing apps sometimes export at reduced size – check the export settings.
A side effect: such copies often lack the capture date too, so the tool can't put the photo into its month automatically.
4:3, 3:2 or square?
| Aspect ratio | Comes from | In the calendar |
|---|---|---|
| 4:3 | Most phones | Fills the full width on top of an A4 portrait page |
| 3:2 | DSLR and mirrorless cameras, 4 × 6 prints | A little flatter, more room for the calendar |
| 16:9 | Videos, wide photos | A wide strip, good for landscapes |
| 1:1 | Square photos, Instagram | Suits 21 × 21 cm and the instant photo layout |
An A4 page has a ratio of 1 : 1.41 – between 4:3 and 3:2 – so full-page photos are always cropped a little. In the tool you avoid that with the photo format “Like the photo”: every frame takes the shape of its photo and nothing is cut off. With “All 4:3” or “3:2” all months look the same.
Portrait or landscape?
- Landscape photos suit “Photo on top, calendar below” and “Calendar on top, photo below”, and full-page photos on landscape calendars.
- Portrait photos suit “Photo left” (with day list or month grid) and full-page photos on portrait calendars.
- When distributing photos automatically, the tool prefers a photo of the right orientation for every frame.
A quality indicator for every photo, frames in the shape of your photos, sorting by capture month.
Preparing photos
- Check on a big screen: blur and camera shake are hard to see on a phone but obvious on a laptop or tablet.
- HEIC photos from an iPhone open directly in the tool. For other programs, convert HEIC to JPG.
- Lighten dark photos slightly – printed, they look darker than on screen.
- Don't upscale artificially: enlarging doesn't bring back real detail. Choose another photo or a layout with a smaller frame instead.
Add photos and design your calendar
Quality indicator, frames in the shape of your photos and a print-ready PDF – free and without upload.
FAQ
What resolution do I need for an A4 photo calendar?
For a full-page photo, 2480 × 3508 pixels at 300 dpi. From about 1860 × 2631 pixels (225 dpi) the result is still good.
Is a phone photo good enough for a photo calendar?
Yes. A 12-megapixel photo gives about 345 dpi on A4. On A3 it's about 244 dpi – still good, but details get slightly softer.
Why are photos from WhatsApp too small?
Messengers scale down and compress photos when sending. Always use the original for printing.
Does the dpi value in the file matter?
No. Only the pixels and the size the photo is printed at matter.
Do I have to crop my photos?
No. With the photo format “Like the photo” the layout adapts to every photo. You can change crops in the tool by dragging and zooming.
What does the red indicator mean?
The photo has less than 225 dpi at its size and will print visibly soft. Zoom out, use a larger original or put the photo in a smaller frame.
Sources
- WIRmachenDRUCK: Druckdaten-Checkliste – bleed, safety margin, resolution, color space (German)
- kalender-druck.de: Hilfe zu Druckdaten – 2 mm bleed, at least 300 dpi (German)