Optimal Alt Description Size

[manintights28]

What is an optimal size for a description of an image without being penalized.

In the past, I would put whole paragraphs in the alt and title tags. These were well structured sentences to avoid the "keyword stuffing." Just wondering whether any research has been done on this element.

[dawnieando]

I haven't seen anything about an optimal alt description size, however I always aim to bear in mind that the true purpose of these is to provide assistance to those who can't see the images.  I always ensure that my target page keyword is in there to tick the SEO box but endeavour to make it useful for those who need it from a human perspective.

[mad2k]

Hi,

I usually use full sentences including a keyword. Have tons of searches for these elements. It is a long tail but it increases site traffic.

In my opinion optimal size is like in the meta - title ... no more than 70 characters.

Marek