Pixels per Inch for Website Photographs

[AceCo55]

Sheesh! Folks the reason low dpi is important on the web is for FAST loading! Try and focus WEB WEB WEB!

... a file of 100K will load faster than a 1M file! nuff said.

Sorry, you have a misconception about ppi affecting file size.
File size is NOT determined, in any way what-so-ever, by the ppi value.

File size is determined by 2 things:
Actual pixel dimensions of the image
The level of "compression" chosen (ie the "quality" level that is chosen when saving ... or if using "Save for Web" or "Export" by the quality level you choose there)
(there is also the content that can change file size but let's not confuse the issue for the moment)

Changing the ppi from 300ppi to 72ppi will have NO affect at all - UNLESS you are forcing the software to "resample" - in THAT case the smaller file size comes from actually throwing away pixels so that the pixel dimensions are now less. Perhaps this is what may be confusing you?

 

[AceCo55]

The OP ask SPECIFICALLY about loading to a website. fitting the picture to a monitor is a disaster. You pic must be usable on a wide range of devices, and various sized monitors. Threfor the 'standard is as I said above: 72-100dpi and 800 to 900 pixels on the long side.

???????????? Not sure what you are reading. I SPECIFICALLY gave the OP some common pixel dimensions and compression vales resulting in small files that would load quickly on their website.
I did mention that if some-one had a large screen then uploading a slightly bigger (pixel dimensions) file would allow it to be seen in all its glory.
Don't believe me?
Try to show a 100 x100 pixel image on a 30" monitor, AT FULL SCREEN, and tell me it doesn't matter!!!
I was just trying to point out that IF the OP wanted to view large images on large screen monitors then 800 pixel wide images may not be so great.

A common size that I said in my post was 800 - 1200 pixels on the long side - JUST AS YOU CONFIRMED in your subsequent post.
The difference is that you (mistakenly) believe changing the ppi value will have an affect on file size ... and that is just wrong.

Changing the pixel dimensions and the level of compression (quality) are the only things to change so that photos will load quickly ON THE WEB!!!

 

[LGreene]

OK, just to get this clear in my head - if PPI has no effect on the quality of a picture displayed on the web OR on the loading time, then why do people (both in this thread and on various articles I have come across) repeatedly recommend using 72PPI when uploading an image to a website?

Thanks again for the help

 

[KmH]

Because those people don't understand what 72 PPI means, and just regurgitate something some other person said that doesn't understand what 72 PPI means.

It is a common problem on the Internet with other subjects and is often referred to as a urban legend.

It actually goes to understanding fundamental math, digital photograph, and computer technology concepts.

 

[Ysarex]

OK, just to get this clear in my head - if PPI has no effect on the quality of a picture displayed on the web OR on the loading time, then why do people (both in this thread and on various articles I have come across) repeatedly recommend using 72PPI when uploading an image to a website?

Thanks again for the help

They watch Youtube.

Joe

 

[mcap1972]

I think the rule of thumb is 75 dpi. The dimension now depend. If you want your photos to looks good on 4k monitors or Retina displays you have to upload at least 2880 x 1800.

 

[snowbear]

I think the rule of thumb is 75 dpi. The dimension now depend. If you want your photos to looks good on 4k monitors or Retina displays you have to upload at least 2880 x 1800.

Rule of thumb? DPI has zero effect on images viewed through a browser.

Which of the following are at 75 DPI?

 

[KmH]

Neither.
DPI is printer resolution.
A DPI value cannot be set in a digital image file.

For confirmation see pages 130 and 131 of
The Digital Print: Preparing Images in Lightroom and Photoshop for Printing

Martin Evening usually covers that in his Photoshop and Lightroom books too.

 

[snowbear]

Neither.
DPI is printer resolution.
A DPI value cannot be set in a digital image file.

For confirmation see pages 130 and 131 of
The Digital Print: Preparing Images in Lightroom and Photoshop for Printing

Martin Evening usually covers that in his Photoshop and Lightroom books too.

Which is precisely my point to @mcap1972, DPI is meaningless on screen.