What is the best resolution for my photos, wall art and posters?

Modified on Fri, 24 Nov, 2023 at 11:08 AM

What is the best resolution for my photos, wall art and posters?
(See below for Aspect Ratios of each print and poster.)

Higher resolution photos are clearer and contain more detail.

Digital image resolution is expressed as pixels (or dots) across by pixels down, such as 640 x 480, meaning 640 pixels across by 480 pixels down. The best printable resolution is 300 dots per inch.

Extremely low resolution will look "blocky" or pixelated. Imagine only 4 dots per inch: you would see four colored squares instead of a picture. When there are many pixels, your mind blends the tiny blocks together to form an image.

The digital camera is the most important factor in determining quality of digital images. The greater the number of pixels (up to 300 per inch), the higher the quality of the digital image. Some low-cost cameras give a set number of pixels and shoot only one resolution. Higher-priced cameras offer a pixel range, which enables you to select the best resolution for the size image you want.

Not all photos require high pixels per inch. For instance, you are likely to stand back from a poster, and your eye will blend the pixels together, so 90 pixels per inch is the minimum recommended resolution for posters. The subject matter can also be important: for instance, if you are printing a picture of a crowd of faces or a group shot, and you want to recognize faces in the crowd, you will need a higher pixel count to ensure that each tiny face has a enough visual information.

Use the following chart as a guide for determining the best resolution for various print sizes. Note that the 4xD (Digital) size is the same ratio as most digital cameras -- 1.333 (1200 x 1600 dots) -- so no cropping is required when printing these photos. The 18x24 and 30x40 also have the same 1.33 ratio and require no cropping for most digital cameras.
Add an eighth of an inch to each side for a perfect print

When creating a print product like a 4x8 card or poster, add 1/8 of an inch to each side. For 300 dots per inch, that's 37.5 pixels or 75 pixels for both sides. A perfect 4x8 card would be ((4x300)+75) X ((8x300)+75) or 1275 by 2475. The 37.5 pixel border is not printed, so no important photo elements (faces, type, etc.) should be in that space. Note that the 1/8 inch pixel border decreases as resolution decreases: at 200 dpi, 1/8 inch is 200/8 or 25 pixels. This also changes the aspect ratio.

Size	Borderline: 150 res	Better: 180 res	Good: 200 res	Best: 300 res	Aspect Ratio (L/S)
Wallets (2"x3")	300 x 450	360 x 540	640 x 480	600 x 900	1.50
4 x D (4 x 5.33)	600 x 800	720 x 960	800 x 1066	1200 x 1600	1.33
4 x 6	600 x 900	720 x 1000	800 x 1200	1200 x 1800	1.50
4 x 8 Card	638 x 1238	765 x 1485	850 x 1650	1275 x 2475	1.94
5 x 7	750 x 1050	900 x 1260	1000 x 1400	1500 x 2100	1.40
8 x 10	1200 x 1500	1200 x 1500	1600 x 2000	2400 x 3000	1.25

Posters	Borderline: 90 res	Better: 150 res	Good: 180 res	Best: 300 res*	Aspect Ratio (L/S)
11 x 14	990 x 1260	1650 x 2100	1980 x 2520	3300 x 4200	1.27
12 x 18	1080 x 1620	1800 x 2700	2160 x 3240	3600 x 5400	1.50
16 x 20	1440 x 1800	2400 x 3000	2880 x 3600	4800 x 6000*	1.25
16 x 24	1440 x 2160	2400 x 3600	2880 x 4320	4000 x 6000*	1.50
18 x 24	1620 x 2160	2700 x 3600	3240 x 4320	4500 x 6000*	1.33
20 x 20	1800 x 1800	3000 x 3000	3600 x 3600	6000 x 6000*	1.00
20 x 24	1800 x 2160	3000 x 3600	3600 x 4320	5000 x 6000*	1.20
20 x 30	1800 x 2700	3000 x 4500	3200 x 4800*	4000 x 6000*	1.50
24 x 36	2160 x 3240	3200 x 4800*	3200 x 4800*	4000 x 6000*	1.50
30 x 40	2700 x 3600	3600 x 4800*	3600 x 4800*	4500 x 6000*	1.33

* The longest side of any uploaded image is a maximum of 6000 dots. When the longest side is 6000, the other side is calculated to have the same number of pixels per inch.

What is the best resolution for a large poster or framed print?
The largest image that dotphoto uploads is 36 megapixels or 6000 x 6000 dots, so, if possible, you want the longest side to be 6000 dots and the shorter side to be proportional. For instance, if you want a print that is 42" x 30", the best possible image would be 6000 x 4286. The image must also be 30MB or less; if the original is more than 30MB, try saving as a JPG or adjusting the JPG compressions.

How can I see the size of my images in dotphoto?

Tap the album you want to inspect.
Tap the Organize menu on the left.
Tap the Edit Titles menu. You will see the Width and the Height in pixels of each photo in the album.